This defines the tracehook_get_signal() hook to allow tracing code to slip
in before normal signal dequeuing. This lays the groundwork for new
tracing features that can inject synthetic signals outside the normal
queue or control the disposition of delivered signals. The calling
convention lets tracehook_get_signal() decide both exactly what will
happen and what signal number to report in the handler/exit.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This defines tracehook_consider_fatal_signal() has a fine-grained hook for
deciding to skip the special cases for a fatal signal, as ptrace does.
There is no change, only cleanup.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This defines tracehook_consider_ignored_signal() has a fine-grained hook
for deciding to prevent the normal short-circuit of sending an ignored
signal, as ptrace does. There is no change, only cleanup.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ptrace_notify() function should not be called by any modules. It was
only ever exported to be called by binfmt exec functions. But that is no
longer necessary since fs/exec.c deals with that generically now. There
should be no calls to ptrace_notify() from outside the core kernel.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function operated on a pid_t to kill a task, which is no longer valid
in a containerized system.
It has finally lost all its users and we can safely remove it from the
tree.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move mm->core_waiters into "struct core_state" allocated on stack. This
shrinks mm_struct a little bit and allows further changes.
This patch mostly does s/core_waiters/core_state. The only essential
change is that coredump_wait() must clear mm->core_state before return.
The coredump_wait()'s path is uglified and .text grows by 30 bytes, this
is fixed by the next patch.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1. SIGKILL can't be blocked, remove this check from sigkill_pending().
2. When ptrace_stop() sees sigkill_pending() == T, it can just return.
Kill "int killed" and simplify the code. This also is more correct,
the tracer shouldn't see us in TASK_TRACED if we are not going to
stop.
I strongly believe this code needs further changes. We should do the "was
this task killed" check unconditionally, currently it depends on
arch_ptrace_stop_needed(). On the other hand, sigkill_pending() isn't
very clever. If the task was killed tkill(SIGKILL), the signal can be
already dequeued if the caller is do_exit().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change the type of pid and tgid variables from int to the POSIX type
pid_t.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the switch to configurable HZ in 2.6, the treatment of the si_utime and
si_stime fields that are exposed to userland via the siginfo structure
looks to have been botched. As things stand, these fields report times in
units of HZ, so that userland gets information that varies depending on
the HZ that the kernel was configured with. This patch changes the
reported values to use USER_HZ units.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fae5fa44f1 changed do_signal_stop() to check
SIGNAL_UNKILLABLE, this wasn't needed. If signal_group_exit() == F, the
signal sent to SIGNAL_UNKILLABLE task must be already filtered out by the
caller, get_signal_to_deliver(). And if signal_group_exit() == T we are
not going to stop.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dequeue_signal() checks SIGNAL_GROUP_EXIT before setting
SIGNAL_STOP_DEQUEUED. This was added by
788e05a67c a long ago to avoid the
coredump/SIGSTOP race.
Since then the related code was changed, and now this subtle check is both
incomplete and unneeded at the same time. It is incomplete because
nowadays exec() doesn't set SIGNAL_GROUP_EXIT, so in fact we should check
signal_group_exit() to avoid a similar race. Fortunately, we doesn't need
the check at all. The only function which relies on SIGNAL_STOP_DEQUEUED
is do_signal_stop(), and it ignores this flag if signal_group_exit() == T,
this covers the SIGNAL_GROUP_EXIT case.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the recent changes collect_signal() always returns true. Change it
to return void and update the single caller.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Factor out sigdelset() calls and remove the "still_pending" variable.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
collect_signal() checks sigismember(&list->signal, sig), this is not
needed. This "sig" was just found by next_signal(), so it must be valid.
We have a (completely broken) call to ->notifier in between, but it must
not play with sigpending->signal bits or unlock ->siglock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The bug was reported and analysed by Mark McLoughlin <markmc@redhat.com>,
the patch is based on his and Roland's suggestions.
posix_timer_event() always rewrites the pre-allocated siginfo before sending
the signal. Most of the written info is the same all the time, but memset(0)
is very wrong. If ->sigq is queued we can race with collect_signal() which
can fail to find this siginfo looking at .si_signo, or copy_siginfo() can
copy the wrong .si_code/si_tid/etc.
In short, sys_timer_settime() can in fact stop the active timer, or the user
can receive the siginfo with the wrong .si_xxx values.
Move "memset(->info, 0)" from posix_timer_event() to alloc_posix_timer(),
change send_sigqueue() to set .si_overrun = 0 when ->sigq is not queued.
It would be nice to move the whole sigq->info initialization from send to
create path, but this is not easy to do without uglifying timer_create()
further.
As Roland rightly pointed out, we need more cleanups/fixes here, see the
"FIXME" comment in the patch. Hopefully this patch makes sense anyway, and
it can mask the most bad implications.
Reported-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: Oliver Pinter <oliver.pntr@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kernel/posix-timers.c | 17 +++++++++++++----
kernel/signal.c | 1 +
2 files changed, 14 insertions(+), 4 deletions(-)
Based on Roland's patch. This approach was suggested by Austin Clements
from the very beginning, and then by Linus.
As Austin pointed out, the execing task can be killed by SI_TIMER signal
because exec flushes the signal handlers, but doesn't discard the pending
signals generated by posix timers. Perhaps not a bug, but people find this
surprising. See http://bugzilla.kernel.org/show_bug.cgi?id=10460
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Austin Clements <amdragon+kernelbugzilla@mit.edu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently sigqueue_free() removes sigqueue from list, but doesn't cancel the
pending signal. This is not consistent, the task should either receive the
"full" signal along with siginfo_t, or it shouldn't receive the signal at all.
Change sigqueue_free() to clear SIGQUEUE_PREALLOC but leave sigqueue on list
if it is queued.
This is a user-visible change. If the signal is blocked, it stays queued
after sys_timer_delete() until unblocked with the "stale" si_code/si_value,
and of course it is still counted wrt RLIMIT_SIGPENDING which also limits
the number of posix timers.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Austin Clements <amdragon+kernelbugzilla@mit.edu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__exit_signal() does flush_sigqueue(tsk->pending) outside of ->siglock.
This can race with another thread doing sigqueue_free(), we can free the
same SIGQUEUE_PREALLOC sigqueue twice or corrupt the pending->list.
Note that even sys_exit_group() can trigger this race, not only
sys_timer_delete().
Move the callsite of flush_sigqueue(tsk->pending) under ->siglock.
This patch doesn't touch flush_sigqueue(->shared_pending) below, it is
called when there are no other threads which can play with signals, and
sigqueue_free() can't be used outside of our thread group.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds the set_restore_sigmask() inline in <linux/thread_info.h> and
replaces every set_thread_flag(TIF_RESTORE_SIGMASK) with a call to it. No
change, but abstracts the details of the flag protocol from all the calls.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the buggy /sbin/init hangs if SIGSEGV/etc happens. The kernel sends
the signal, init dequeues it and ignores, returns from the exception, repeats
the faulting instruction, and so on forever.
Imho, such a behaviour is not good. I think that the explicit loud death of
the buggy /sbin/init is better than the silent hang.
Change force_sig_info() to clear SIGNAL_UNKILLABLE when the task should be
really killed.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The global init has a lot of long standing problems with the unhandled fatal
signals.
- The "is_global_init(current)" check in get_signal_to_deliver()
protects only the main thread. Sub-thread can dequee the fatal
signal and shutdown the whole thread group except the main thread.
If it dequeues SIGSTOP /sbin/init will be stopped, this is not
right too. Note that we can't use is_global_init(->group_leader),
this breaks exec and this can't solve other problems we have.
- Even if afterwards ignored, the fatal signals sets SIGNAL_GROUP_EXIT
on delivery. This breaks exec, has other bad implications, and this
is just wrong.
Introduce the new SIGNAL_UNKILLABLE flag to fix these problems. It also helps
to solve some other problems addressed by the subsequent patches.
Currently we use this flag for the global init only, but it could also be used
by kthreads and (perhaps) by the sub-namespace inits.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that task_session() can't return a false NULL, check_kill_permission()
doesn't need tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This wasn't documented, but as Atsushi Tsuji pointed out
check_kill_permission() needs tasklist_lock for task_session_nr(). I missed
this fact when removed tasklist from the callers.
Change check_kill_permission() to take tasklist_lock for the SIGCONT case.
Re-order security checks so that we take tasklist_lock only if/when it is
actually needed. This is a minimal fix for now, tasklist will be removed
later.
Also change the code to use task_session() instead of task_session_nr().
Also, remove the SIGCONT check from cap_task_kill(), it is bogus (and the
whole function is bogus. Serge, Eric, why it is still alive?).
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Atsushi Tsuji <a-tsuji@bk.jp.nec.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
send_signal() shouldn't call signalfd_notify() if it then fails with -EAGAIN.
Harmless, just a paranoid cleanup.
Also remove the comment. It is obsolete, signalfd_notify() was simplified and
does a simple wakeup.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A couple of small comments about how CLD_CONTINUED notification works.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename handle_stop_signal() to prepare_signal(), make it return a boolean, and
move the callsites of sig_ignored() into it.
No functional changes for now. But it would be nice to factor out the "should
we drop this signal" checks as much as possible, before we try to fix the bugs
with the sub-namespace init's signals (actually the global /sbin/init has some
problems with signals too).
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the callsite of print_fatal_signal() down, under "if
(sig_kernel_coredump(signr))", so we don't need to check signr != SIGKILL.
We are only interested in the sig_kernel_coredump() signals anyway, and due to
the previous changes we almost never can see other fatal signals here except
SIGKILL.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
handle_stop_signal() clears SIGNAL_STOP_DEQUEUED when sig == SIGKILL. Remove
this nasty special case. It was needed to prevent the race with group stop
and exit caused by thread-specific SIGKILL. Now that we use complete_signal()
for private signals too this is not needed, complete_signal() will notice
SIGKILL and abort the soon-to-begin group stop.
Except: the target thread is dead (has PF_EXITING). But in that case we
should not just clear SIGNAL_STOP_DEQUEUED and nothing more. We should either
kill the whole thread group, or silently ignore the signal.
I suspect we are not right wrt zombie leaders, but this is another issue which
and should be fixed separately. Note that this check can't abort the group
stop if it was already started/finished, this check only adds a subtle side
effect if we race with the thread which has already dequeued sig_kernel_stop()
signal and temporary released ->siglock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We export send_sigqueue() and send_group_sigqueue() for the only user,
posix_timer_event(). This is a bit silly, because both are just trivial
helpers on top of do_send_sigqueue() and because the we pass the unused
.si_signo parameter.
Kill them both, rename do_send_sigqueue() to send_sigqueue(), and export it.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested by Pavel Emelyanov.
send_sigqueue/send_group_sigqueue are only differ in how they lock ->siglock.
Unify them. send_group_sigqueue() uses spin_lock() because it knows the task
can't exit, but in that case lock_task_sighand() can't fail and doesn't hurt.
Note that the "sig" argument is ignored, it is always equal to ->si_signo.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Factor out complete_signal() callsites. This change completely unifies the
helpers sending the specific/group signals.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Based on Pavel Emelyanov's suggestion.
Rename __group_complete_signal() to complete_signal() and use it to process
the specific signals too. To do this we simply add the "int group" argument.
This allows us to greatly simply the signal-sending code and adds a useful
behaviour change. We can avoid the unneeded wakeups for the private signals
because wants_signal() is more clever than sigismember(blocked), but more
importantly we now take into account the fatal specific signals too.
The latter allows us to kill some subtle checks in handle_stop_signal() and
makes the specific/group signal's behaviour more consistent. For example,
currently sigtimedwait(FATAL_SIGNAL) behaves differently depending on was the
signal sent by kill() or tkill() if the signal was not blocked.
And. This allows us to tweak/fix the behaviour when the specific signal is
sent to the dying/dead ->group_leader.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
send_signal() is used either with ->pending or with ->signal->shared_pending.
Change it to take "int group" instead, this argument will be re-used later.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the unchanged definition of __group_complete_signal() so that send_signal
can see it. To simplify the reading of the next patches.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested by Roland McGrath.
Initialize signal->curr_target in copy_signal(). This way ->curr_target is
never == NULL, we can kill the check in __group_complete_signal's hot path.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The comment in send_sig_info() is wrong, tasklist_lock can't help.
The caller must ensure the task can't go away, otherwise ->sighand can be NULL
even before we take the lock.
p->sighand could be changed by exec(), but I can't imagine how it is possible
to prevent exit(), but not exec().
Since the things seem to work, I assume all callers are correct. However,
drm_vbl_send_signals() looks broken. block_all_signals() which is solely used
by drm is definitely broken.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert do_tkill() to use rcu_read_lock() + lock_task_sighand() to avoid
taking tasklist lock.
Note that we don't return an error if lock_task_sighand() fails, we pretend
the task dies after receiving the signal. Otherwise, we should fight with the
nasty races with mt-exec without having any advantage.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move handle_stop_signal() into send_signal(). This factors out a couple of
callsites and allows us to do further unifications.
Also, with this change specific_send_sig_info() does handle_stop_signal().
Not that this is really important, we never send STOP/CONT via send_sig() and
friends, but still this looks more consistent.
The only (afaics) special case is get_signal_to_deliver(). If the traced task
dequeues SIGCONT, it can re-send it to itself after ptrace_stop() if the
signal was blocked by debugger. In that case handle_stop_signal() is
unnecessary, but hopefully not a problem.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
handle_stop_signal() was changed, now send_group_sigqueue() doesn't need
tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cosmetic, cache p->signal to make the code a bit more readable.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
send_group_sigqueue() calls handle_stop_signal(), send_sigqueue() doesn't.
This is not consistent and in fact I'd say this is (minor) bug.
Move handle_stop_signal() from send_group_sigqueue() to do_send_sigqueue(),
the latter is called by send_sigqueue() too.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lock_task_sighand() was changed, send_sigqueue() doesn't need rcu_read_lock()
any longer.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cache the values of current->signal/sighand. Shrinks .text a bit and makes
the code more readable. Also, remove "sigset_t *mask", it is pointless
because in fact we save the constant offset.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cache the value of p->signal, and change the code to use while_each_thread()
helper.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that handle_stop_signal() doesn't drop ->siglock, we can't see both
->group_stop_count && SIGNAL_STOP_STOPPED. Merge two "if" branches.
As Roland pointed out, we never actually needed 2 do_notify_parent_cldstop()
calls.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously handle_stop_signal(SIGCONT) could drop ->siglock. That is why
kill_pid_info(SIGCONT) takes tasklist_lock to make sure the target task can't
go away after unlock. Not needed now.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Based on discussion with Jiri and Roland.
In short: currently handle_stop_signal(SIGCONT, p) sends the notification to
p->parent, with this patch p itself notifies its parent when it becomes
running.
handle_stop_signal(SIGCONT) has to drop ->siglock temporary in order to notify
the parent with do_notify_parent_cldstop(). This leads to multiple problems:
- as Jiri Kosina pointed out, the stopped task can resume without
actually seeing SIGCONT which may have a handler.
- we race with another sig_kernel_stop() signal which may come in
that window.
- we race with sig_fatal() signals which may set SIGNAL_GROUP_EXIT
in that window.
- we can't avoid taking tasklist_lock() while sending SIGCONT.
With this patch handle_stop_signal() just sets the new SIGNAL_CLD_CONTINUED
flag in p->signal->flags and returns. The notification is sent by the first
task which returns from finish_stop() (there should be at least one) or any
other signalled thread from get_signal_to_deliver().
This is a user-visible change. Say, currently kill(SIGCONT, stopped_child)
can't return without seeing SIGCHLD, with this patch SIGCHLD can be delayed
unpredictably. Another difference is that if the child is ptraced by another
process, CLD_CONTINUED may be delivered to ->real_parent after ptrace_detach()
while currently it always goes to the tracer which doesn't actually need this
notification. Hopefully not a problem.
The patch asks for the futher obvious cleanups, I'll send them separately.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every implementation of ->task_kill() does nothing when the signal comes from
the kernel. This is correct, but means that check_kill_permission() should
call security_task_kill() only for SI_FROMUSER() case, and we can remove the
same check from ->task_kill() implementations.
(sadly, check_kill_permission() is the last user of signal->session/__session
but we can't s/task_session_nr/task_session/ here).
NOTE: Eric W. Biederman pointed out cap_task_kill() should die, and I think
he is very right.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: David Quigley <dpquigl@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Cc: Harald Welte <laforge@gnumonks.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both functions do the same thing after proper locking, but with
different sigpending structs, so move the common code into a helper.
After this we have 4 places that look very similar: send_sigqueue: calls
do_send_sigqueue and signal_wakeup send_group_sigqueue: calls
do_send_sigqueue and __group_complete_signal __group_send_sig_info:
calls send_signal and __group_complete_signal specific_send_sig_info:
calls send_signal and signal_wakeup
Besides, send_signal performs actions similar to do_send_sigqueue's
and __group_complete_signal - to signal_wakeup.
It looks like they can be consolidated gracefully.
Oleg said:
Personally, I think this change is very good. But send_sigqueue() and
send_group_sigqueue() have a very subtle difference which I was never able
to understand.
Let's suppose that sigqueue is already queued, and the signal is ignored
(the latter means we should re-schedule cpu timer or handle overrruns). In
that case send_sigqueue() returns 0, but send_group_sigqueue() returns 1.
I think this is not the problem (in fact, I think this patch makes the
behaviour more correct), but I hope Thomas can take a look and confirm.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The signr variable may be declared without initialization - it is set ro the
return value from __dequeue_signal() right at the function beginning.
Besides, after recalc_sigpending() two checks for signr to be not 0 may be
merged into one. Both if-s become easier to read.
Thanks to Oleg for pointing out mistakes in the first version of this patch.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both sig_ignored() and do_sigaction() check for signr to be explicitly or
implicitly ignored. Introduce a helper for them.
This patch is aimed to help handling signals by pid namespace's init, and was
derived from one of Oleg's patches
https://lists.linux-foundation.org/pipermail/containers/2007-December/009308.html
so, if he doesn't mind, he should be considered as an author.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most of the callers of lock_task_sighand() doesn't actually need rcu_lock().
lock_task_sighand() needs it only to safely play with tsk->sighand, it can
take the lock itself.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_signal_stop() needs signal_group_exit() but checks sig->group_exit_task.
This (optimization) is correct, SIGNAL_STOP_DEQUEUED and SIGNAL_GROUP_EXIT
are mutually exclusive, but looks confusing. Use signal_group_exit(), this
is not fastpath, the code clarity is more important.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Two callers for send_signal() - the specific_send_sig_info and the
__group_send_sig_info - both check for sig to be ignored or already queued.
Move these checks into send_signal() and make it return 1 to indicate that the
signal is dropped, but there's no error in this.
Besides, merge comments and spell-check them.
[oleg@tv-sign.ru: simplifications]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes the code more readable, due to less brackets and small letters in
name.
I also move it above the send_signal() as a preparation for the 3rd patch.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function doesn't change the ret's value and thus always returns 0, with a
single exception of returning -EAGAIN explicitly.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These are small cleanups all over the tree.
Trivial style and comment changes to
fs/select.c, kernel/signal.c, kernel/stop_machine.c & mm/pdflush.c
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
This breaks out the ptrace handling from get_signal_to_deliver into a
new subroutine. The actual code there doesn't change, and it gets
inlined into nearly identical compiled code. This makes the function
substantially shorter and thus easier to read, and it nicely isolates
the ptrace magic.
Signed-off-by: Roland McGrath <roland@redhat.com>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This changes the "freezer" code used by suspend/hibernate in its treatment
of tasks in TASK_STOPPED (job control stop) and TASK_TRACED (ptrace) states.
As I understand it, the intent of the "freezer" is to hold all tasks
from doing anything significant. For this purpose, TASK_STOPPED and
TASK_TRACED are "frozen enough". It's possible the tasks might resume
from ptrace calls (if the tracer were unfrozen) or from signals
(including ones that could come via timer interrupts, etc). But this
doesn't matter as long as they quickly block again while "freezing" is
in effect. Some minor adjustments to the signal.c code make sure that
try_to_freeze() very shortly follows all wakeups from both kinds of
stop. This lets the freezer code safely leave stopped tasks unmolested.
Changing this fixes the longstanding bug of seeing after resuming from
suspend/hibernate your shell report "[1] Stopped" and the like for all
your jobs stopped by ^Z et al, as if you had freshly fg'd and ^Z'd them.
It also removes from the freezer the arcane special case treatment for
ptrace'd tasks, which relied on intimate knowledge of ptrace internals.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fastcall always expands to empty, remove it.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's only one caller left - the kill_pgrp one - so merge these two
functions and forget the kill_pgrp_info one.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Reviewed-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the first step (of two) in removing the kill_pgrp_info.
All the users of this function are in kernel/signal.c, but all they need is to
call __kill_pgrp_info() with the tasklist_lock read-locked.
Fortunately, one of its users is the kill_something_info(), which already
needs this lock in one of its branches, so clean these branches up and call
the __kill_pgrp_info() directly.
Based on Oleg's view of how this function should look.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
signal_struct->tsk points to the ->group_leader and thus we have the nasty
code in de_thread() which has to change it and restart ->real_timer if the
leader is changed.
Use "struct pid *leader_pid" instead. This also allows us to kill now
unneeded send_group_sig_info().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kill_pid_info()->pid_task() could be the old leader of the execing process.
In that case it is possible that the leader will be released before we take
siglock. This means that kill_pid_info() (and thus sys_kill()) can return a
false -ESRCH.
Change the code to retry when lock_task_sighand() fails. The endless loop is
not possible, __exit_signal() both clears ->sighand and does detach_pid().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The previous bugfix was not optimal, we shouldn't care about group stop
when we are the only thread or the group stop is in progress. In that case
nothing special is needed, just set PF_EXITING and return.
Also, take the related "TIF_SIGPENDING re-targeting" code from exit_notify().
So, from the performance POV the only difference is that we don't trust
!signal_pending() until we take ->siglock. But this in fact fixes another
___pure___ theoretical minor race. __group_complete_signal() finds the
task without PF_EXITING and chooses it as the target for signal_wake_up().
But nothing prevents this task from exiting in between without noticing the
pending signal and thus unpredictably delaying the actual delivery.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_signal_stop() counts all sub-thread and sets ->group_stop_count
accordingly. Every thread should decrement ->group_stop_count and stop,
the last one should notify the parent.
However a sub-thread can exit before it notices the signal_pending(), or it
may be somewhere in do_exit() already. In that case the group stop never
finishes properly.
Note: this is a minimal fix, we can add some optimizations later. Say we
can return quickly if thread_group_empty(). Also, we can move some signal
related code from exit_notify() to exit_signals().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the tracer is gone and we are not going to stop, ptrace_stop() sets
->exit_code = nostop_code. However, the tracer could actually clear the
exit code before detaching. In that case get_signal_to_deliver() "resends"
the signal which was cancelled by the debugger. For example, it is
possible that a quick PTRACE_ATTACH + PTRACE_DETACH can leave the tracee in
STOPPED state.
Change the behaviour of ptrace_stop(). If the caller is ptrace notify(),
we should always clear ->exit_code. If the caller is
get_signal_to_deliver(), we should not touch it at all. To do so, change
the nonstop_code parameter to "bool clear_code" and change the callers
accordingly.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the tracer went away (may_ptrace_stop() failed), ptrace_stop() drops
tasklist and then changes the ->state from TASK_TRACED to TASK_RUNNING.
This can fool another tracer which attaches to us in between. Change the
->state under tasklist_lock to ensure that ptrace_check_attach() can't wrongly
succeed. Also, remove the unnecessary mb().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the patch
"Fix ptrace_attach()/ptrace_traceme()/de_thread() race"
commit f5b40e363a
we set PT_ATTACHED and change child->parent "atomically" wrt task_list lock.
This means we can remove the checks like "PT_ATTACHED && ->parent != ptracer"
which were needed to catch the "ptrace attach is in progress" case. We can
also remove the flag itself since nobody else uses it.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds support to allow asm/ptrace.h to define two new macros,
arch_ptrace_stop_needed and arch_ptrace_stop. These control special
machine-specific actions to be done before a ptrace stop. The new code
compiles away to nothing when the new macros are not defined. This is the
case on all machines to begin with.
On ia64, these macros will be defined to solve the long-standing issue of
ptrace vs register backing store.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1. It is much easier to grep for ->state change if __set_task_state() is used
instead of the direct assignment.
2. ptrace_stop() and handle_group_stop() use set_task_state() which adds the
unneeded mb() (btw even if we use mb() it is still possible that do_wait()
sees the new ->state but not ->exit_code, but this is ok).
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As Roland pointed out, we have the very old problem with exec. de_thread()
sets SIGNAL_GROUP_EXIT, kills other threads, changes ->group_leader and then
clears signal->flags. All signals (even fatal ones) sent in this window
(which is not too small) will be lost.
With this patch exec doesn't abuse SIGNAL_GROUP_EXIT. signal_group_exit(),
the new helper, should be used to detect exit_group() or exec() in progress.
It can have more users, but this patch does only strictly necessary changes.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Holt <holt@sgi.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every time we set SIGNAL_GROUP_EXIT or clear SIGNAL_STOP_DEQUEUED we also
reset ->group_stop_count.
This means that the SIGNAL_GROUP_EXIT check in handle_group_stop() is not
needed, and do_signal_stop() should check SIGNAL_STOP_DEQUEUED only when
->group_stop_count == 0. With these changes handle_group_stop() becomes the
subset of do_signal_stop(), we can kill it and use do_signal_stop() instead.
Also, a preparation for the next patch.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Holt <holt@sgi.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When __group_complete_signal() sees sig_kernel_coredump() signal, it starts
the group stop, but sets ->group_exit_task = t in a hope that "t" will
actually dequeue this signal and invoke do_coredump(). However, by the
time "t" enters get_signal_to_deliver() it is possible that the signal was
blocked/ignored or we have another pending !SIG_KERNEL_COREDUMP_MASK signal
which will be dequeued first. This means the task could be stopped but not
killed.
Remove this code from __group_complete_signal(). Note also this patch
removes the bogus signal_wake_up(t, 1). This thread can't be
STOPPED/TRACED, note the corresponding check in wants_signal().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Holt <holt@sgi.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It may be used by the modules nfs.ko and sunrpc.ko
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ Made it a regular export rather than GPL-only - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc: (22 commits)
Remove commented-out code copied from NFS
NFS: Switch from intr mount option to TASK_KILLABLE
Add wait_for_completion_killable
Add wait_event_killable
Add schedule_timeout_killable
Use mutex_lock_killable in vfs_readdir
Add mutex_lock_killable
Use lock_page_killable
Add lock_page_killable
Add fatal_signal_pending
Add TASK_WAKEKILL
exit: Use task_is_*
signal: Use task_is_*
sched: Use task_contributes_to_load, TASK_ALL and TASK_NORMAL
ptrace: Use task_is_*
power: Use task_is_*
wait: Use TASK_NORMAL
proc/base.c: Use task_is_*
proc/array.c: Use TASK_REPORT
perfmon: Use task_is_*
...
Fixed up conflicts in NFS/sunrpc manually..
We have a lot of code which differs only by the naming of specific
members of structures that contain registers. In order to enable
additional unifications, this patch drops the e- or r- size prefix
from the register names in struct pt_regs, and drops the x- prefixes
for segment registers on the 32-bit side.
This patch also performs the equivalent renames in some additional
places that might be candidates for unification in the future.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Set TASK_WAKEKILL for TASK_STOPPED and TASK_TRACED, add TASK_KILLABLE and
use TASK_WAKEKILL in signal_wake_up()
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
While a signal is blocked, it must be posted even if its action is
SIG_IGN or is SIG_DFL with the default action to ignore. This works
right most of the time, but is broken when a sigwait (rt_sigtimedwait)
is in progress. This changes the early-discard check to respect
real_blocked. ~blocked is the set to check for "should wake up now",
but ~(blocked|real_blocked) is the set for "blocked" semantics as
defined by POSIX.
This fixes bugzilla entry 9347, see
http://bugzilla.kernel.org/show_bug.cgi?id=9347
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Do not allow processes to clear their TIF_SIGPENDING if TIF_FREEZE is set,
so that they will not race with the freezer (like mysqld does, for example).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@suspend2.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't undef __i386__/__x86_64__ in uml anymore, make sure that (few) places
that required adjusting the ifdefs got those.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The task_struct->pid member is going to be deprecated, so start
using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in
the kernel.
The first thing to start with is the pid, printed to dmesg - in
this case we may safely use task_pid_nr(). Besides, printks produce
more (much more) than a half of all the explicit pid usage.
[akpm@linux-foundation.org: git-drm went and changed lots of stuff]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With pid namespaces this field is now dangerous to use explicitly, so hide
it behind the helpers.
Also the pid and pgrp fields o task_struct and signal_struct are to be
deprecated. Unfortunately this patch cannot be sent right now as this
leads to tons of warnings, so start isolating them, and deprecate later.
Actually the p->tgid == pid has to be changed to has_group_leader_pid(),
but Oleg pointed out that in case of posix cpu timers this is the same, and
thread_group_leader() is more preferable.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The find_task_by_something is a set of macros are used to find task by pid
depending on what kind of pid is proposed - global or virtual one. All of
them are wrappers above the most generic one - find_task_by_pid_type_ns() -
and just substitute some args for it.
It turned out, that dereferencing the current->nsproxy->pid_ns construction
and pushing one more argument on the stack inline cause kernel text size to
grow.
This patch moves all this stuff out-of-line into kernel/pid.c. Together
with the next patch it saves a bit less than 400 bytes from the .text
section.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the largest patch in the set. Make all (I hope) the places where
the pid is shown to or get from user operate on the virtual pids.
The idea is:
- all in-kernel data structures must store either struct pid itself
or the pid's global nr, obtained with pid_nr() call;
- when seeking the task from kernel code with the stored id one
should use find_task_by_pid() call that works with global pids;
- when showing pid's numerical value to the user the virtual one
should be used, but however when one shows task's pid outside this
task's namespace the global one is to be used;
- when getting the pid from userspace one need to consider this as
the virtual one and use appropriate task/pid-searching functions.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: yet nuther build fix]
[akpm@linux-foundation.org: remove unneeded casts]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Only the global-init process must be special - any other cgroup-init
process must be killable to prevent run-away processes in the system.
TODO: Ideally we should allow killing the cgroup-init only from parent
cgroup and prevent it being killed from within the cgroup.
But that is a more complex change and will be addressed by a follow-on
patch. For now allow the cgroup-init to be terminated by any process
with sufficient privileges.
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
is_init() is an ambiguous name for the pid==1 check. Split it into
is_global_init() and is_container_init().
A cgroup init has it's tsk->pid == 1.
A global init also has it's tsk->pid == 1 and it's active pid namespace
is the init_pid_ns. But rather than check the active pid namespace,
compare the task structure with 'init_pid_ns.child_reaper', which is
initialized during boot to the /sbin/init process and never changes.
Changelog:
2.6.22-rc4-mm2-pidns1:
- Use 'init_pid_ns.child_reaper' to determine if a given task is the
global init (/sbin/init) process. This would improve performance
and remove dependence on the task_pid().
2.6.21-mm2-pidns2:
- [Sukadev Bhattiprolu] Changed is_container_init() calls in {powerpc,
ppc,avr32}/traps.c for the _exception() call to is_global_init().
This way, we kill only the cgroup if the cgroup's init has a
bug rather than force a kernel panic.
[akpm@linux-foundation.org: fix comment]
[sukadev@us.ibm.com: Use is_global_init() in arch/m32r/mm/fault.c]
[bunk@stusta.de: kernel/pid.c: remove unused exports]
[sukadev@us.ibm.com: Fix capability.c to work with threaded init]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: Pavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename the child_reaper() function to task_child_reaper() to be similar to
other task_* functions and to distinguish the function from 'struct
pid_namspace.child_reaper'.
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The set of functions process_session, task_session, process_group and
task_pgrp is confusing, as the names can be mixed with each other when looking
at the code for a long time.
The proposals are to
* equip the functions that return the integer with _nr suffix to
represent that fact,
* and to make all functions work with task (not process) by making
the common prefix of the same name.
For monotony the routines signal_session() and set_signal_session() are
replaced with task_session_nr() and set_task_session(), especially since they
are only used with the explicit task->signal dereference.
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The freezer should not send signals to kernel threads, since that may lead to
subtle problems. In particular, commit
b74d0deb96 has changed recalc_sigpending_tsk()
so that it doesn't clear TIF_SIGPENDING. For this reason, if the freezer
continues to send fake signals to kernel threads and the freezing of kernel
threads fails, some of them may be running with TIF_SIGPENDING set forever.
Accordingly, recalc_sigpending_tsk() shouldn't set the task's TIF_SIGPENDING
flag if TIF_FREEZE is set.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_sigaction() returns -ERESTARTNOINTR if signal_pending(). The comment says:
* If there might be a fatal signal pending on multiple
* threads, make sure we take it before changing the action.
I think this is not needed. We should only worry about SIGNAL_GROUP_EXIT case,
bit it implies a pending SIGKILL which can't be cleared by do_sigaction.
Kill this special case.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cleanup. __group_complete_signal() wakes up ->group_exit_task twice. The
second wakeup's state includes TASK_UNINTERRUPTIBLE, which is not very
appropriate.
Change the code to pass the "correct" argument to signal_wake_up() and kill
now unneeded wake_up_process().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nowadays thread_group_empty() and next_thread() are simple list operations,
this optimization doesn't make sense: we are doing exactly same check one
line below.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the recent changes, do_sigaction()->recalc_sigpending_and_wake() can
never clear TIF_SIGPENDING. Instead, it can set this flag and wake up the
thread without any reason. Harmless, but unneeded and wastes CPU.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Async signals should not be reported as sent by current in audit log. As
it is, we call audit_signal_info() too early in check_kill_permission().
Note that check_kill_permission() has that test already - it needs to know
if it should apply current-based permission checks. So the solution is to
move the call of audit_signal_info() between those.
Bogosity in question is easily reproduced - add a rule watching for e.g.
kill(2) from specific process (so that audit_signal_info() would not
short-circuit to nothing), say load_policy, watch the bogus OBJ_PID entry
in audit logs claiming that write(2) on selinuxfs file issued by
load_policy(8) had somehow managed to send a signal to syslogd...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This simplifies signalfd code, by avoiding it to remain attached to the
sighand during its lifetime.
In this way, the signalfd remain attached to the sighand only during
poll(2) (and select and epoll) and read(2). This also allows to remove
all the custom "tsk == current" checks in kernel/signal.c, since
dequeue_signal() will only be called by "current".
I think this is also what Ben was suggesting time ago.
The external effect of this, is that a thread can extract only its own
private signals and the group ones. I think this is an acceptable
behaviour, in that those are the signals the thread would be able to
fetch w/out signalfd.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Spotted by taoyue <yue.tao@windriver.com> and Jeremy Katz <jeremy.katz@windriver.com>.
collect_signal: sigqueue_free:
list_del_init(&first->list);
if (!list_empty(&q->list)) {
// not taken
}
q->flags &= ~SIGQUEUE_PREALLOC;
__sigqueue_free(first); __sigqueue_free(q);
Now, __sigqueue_free() is called twice on the same "struct sigqueue" with the
obviously bad implications.
In particular, this double free breaks the array_cache->avail logic, so the
same sigqueue could be "allocated" twice, and the bug can manifest itself via
the "impossible" BUG_ON(!SIGQUEUE_PREALLOC) in sigqueue_free/send_sigqueue.
Hopefully this can explain these mysterious bug-reports, see
http://marc.info/?t=118766926500003http://marc.info/?t=118466273000005
Alexey Dobriyan reports this patch makes the difference for the testcase, but
nobody has an access to the application which opened the problems originally.
Also, this patch removes tasklist lock/unlock, ->siglock is enough.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: taoyue <yue.tao@windriver.com>
Cc: Jeremy Katz <jeremy.katz@windriver.com>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Roland McGrath <roland@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dequeue_signal:
if (__SI_TIMER) {
spin_unlock(&tsk->sighand->siglock);
do_schedule_next_timer(info);
spin_lock(&tsk->sighand->siglock);
}
Unless tsk == curent, this is absolutely unsafe: nothing prevents tsk from
exiting. If signalfd was passed to another process, do_schedule_next_timer()
is just wrong.
Add yet another "tsk == current" check into dequeue_signal().
This patch fixes an oopsable bug, but breaks the scheduling of posix timers
if the shared __SI_TIMER signal was fetched via signalfd attached to another
sub-thread. Mostly fixed by the next patch.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Roland McGrath <roland@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
