Commit Graph

16883 Commits

Author SHA1 Message Date
David Woodhouse
623703f620 [PATCH] Fix code that saves NVGPRS in 32-bit signal frame
On Thu, 2005-11-24 at 12:51 +0000, David Woodhouse wrote:
> Somehow this one slipped through the cracks; when we ended up in
> do_signal() on a 32-bit kernel but without having the caller-saved
> registers into the regs, we didn't set the TIF_SAVE_NVGPRS flag to
> ensure they got saved later.

Oh, and if we actually set the flag, then we fairly quickly find out
that I was a bit overzealous in copying code from entry_64.S ... :)

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:48 +11:00
David Woodhouse
9687c58759 [PATCH] Save NVGPRS in 32-bit signal frame
Somehow this one slipped through the cracks; when we ended up in
do_signal() on a 32-bit kernel but without having the caller-saved
registers into the regs, we didn't set the TIF_SAVE_NVGPRS flag to
ensure they got saved later.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:45 +11:00
David Woodhouse
31df1678d7 [PATCH] powerpc: serial port discovery: cope with broken firmware
On Tue, 2005-11-22 at 15:49 +1100, Benjamin Herrenschmidt wrote:
> This moves the discovery of legacy serial ports to a separate file,
> makes it common to ppc32 and ppc64, and reworks it to use the new OF
> address translators to get to the ports early. This new version can also
> detect some PCI serial cards using legacy chips and will probably match
> those discovered port with the default console choice.

This makes it deal with the fact that the Pegasos firmware reports that
its clock frequency is zero...

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:42 +11:00
Benjamin Herrenschmidt
9177ae4378 [PATCH] powerpc: Fix g5 build with xmon
My previous patches inadvertently broke building a G5 kernel with
CONFIG_XMON enabled. This fixes it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:38 +11:00
David Gibson
404849bbd2 [PATCH] powerpc: Remove some unneeded fields from the paca
This patch removes several unnecessary fields from the paca:

- next_jiffy_update_tb was simply unused.  Remove trivially.

- The exdsi exception save area was not used.  There were plans to use
  it, but they never seem to have gone anywhere.  If they ever do, we
  can put it back.  Remove from the paca, and from asm-offsets.c

- The default_decr field was used from asm, but was only ever assigned
  the value of tb_ticks_per_jiffy.  Just access tb_ticks_per_jiffy from
  asm directly instead.

Built and booted on POWER5 LPAR and iSeries RS64.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:35 +11:00
David Gibson
1888e7b51c [PATCH] powerpc: Remove ItLpRegSave area from the paca
On iSeries, the paca contains, amongst other things an ItLpRegSave
structure used by the hypervisor to save registers.  The hypervisor
locates this area through a pointer at the beginning of the paca, so
the structure itself can be located elsewhere.  This patch moves the
reg_save area out into its own array.  This reduces the amount of
iSeries specific gunk which is visible to general powerpc code via
paca.h

Built and booted on POWER5 LPAR and iSeries RS64.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:32 +11:00
David Gibson
456752f750 [PATCH] powerpc: Make hugepage mappings respect hint addresses
Currently, the powerpc version of hugetlb_get_unmapped_area() entirely
ignores the hint address.  The only way to get a hugepage mapping at a
specified address is with MAP_FIXED, in which case there's no way
(short of parsing /proc/self/maps) for userspace to tell if it will
clobber an existing mapping.  This is inconvenient, so the patch below
makes hugepage mappings use the given hint address if possible.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:28 +11:00
Kumar Gala
706e6b2caf [PATCH] powerpc: Fix suboptimal uImage target
Sam Ravnborg pointed out that calling if_changed was redundant in the
rule since a prerequisite had to have changed for us to get there.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:25 +11:00
Kumar Gala
8c441a57d7 [PATCH] powerpc: Add support for building uImages
powerpc: Add support for building uImages

Add support to build a kernel image bootable by u-boot.
Most of the makefile foo is taken from arch/ppc/boot/images/Makefile

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:21 +11:00
Stephen Rothwell
1d7a6b97f3 powerpc: more iseries irq work
Make get_IRQ return a pending irq number so it can be handled
in the powerpc geeneric code.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
2006-01-09 14:50:18 +11:00
Stephen Rothwell
a50b56d24c powerpc: reduce include in irq.c
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
2006-01-09 14:50:15 +11:00
Stephen Rothwell
e199500c62 powerpc: partly merge iseries do_IRQ
Hide some of the iseries details in iSeries_get_irq.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
2006-01-09 14:50:11 +11:00
Stephen Rothwell
853f828cfd powerpc: use end_IRQ for iseries irqs
Encode the sub bus number into the real irq number (even though it
is always zero for now) so that we have enough information to do
the EOI in iseries_end_IRQ.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
2006-01-09 14:50:08 +11:00
Stephen Rothwell
60798c6a27 powerpc: cleanup iseries irq.c
Remove two useless counters.
DeStropify.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
2006-01-09 14:50:05 +11:00
Benjamin Herrenschmidt
2c5bd01f8f [PATCH] powerpc: convert macio_asic to use prom_parse
Converts the macio_asic core to use the new OF parsing routines instead
of relying on the pre-parsed values in struct device_node.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:50:01 +11:00
Benjamin Herrenschmidt
d7f3945420 [PATCH] powerpc: Add back support for booting from BootX (#2)
ARCH=powerpc couldn't boot from BootX as it uses a "different" way of
getting in the kernel. This patch adds the necessary trampolines,
creating a flattened device-tree from the tree passed from MacOS, and
initializing the btext engine early for really-early debugging.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:58 +11:00
Benjamin Herrenschmidt
51d3082fe6 [PATCH] powerpc: Unify udbg (#2)
This patch unifies udbg for both ppc32 and ppc64 when building the
merged achitecture. xmon now has a single "back end". The powermac udbg
stuff gets enriched with some ADB capabilities and btext output. In
addition, the early_init callback is now called on ppc32 as well,
approx. in the same order as ppc64 regarding device-tree manipulations.
The init sequences of ppc32 and ppc64 are getting closer, I'll unify
them in a later patch.

For now, you can force udbg to the scc using "sccdbg" or to btext using
"btextdbg" on powermacs. I'll implement a cleaner way of forcing udbg
output to something else than the autodetected OF output device in a
later patch.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:54 +11:00
Benjamin Herrenschmidt
463ce0e103 [PATCH] powerpc: serial port discovery (#2)
This moves the discovery of legacy serial ports to a separate file,
makes it common to ppc32 and ppc64, and reworks it to use the new OF
address translators to get to the ports early. This new version can also
detect some PCI serial cards using legacy chips and will probably match
those discovered port with the default console choice.

Only ppc64 gets udbg still yet, unifying udbg isn't finished yet.

It also adds some speed-probing code to udbg so that the default console
can come up at the same speed it was set to by the firmware.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:50 +11:00
Benjamin Herrenschmidt
d1405b8698 [PATCH] powerpc: Add OF address parsing code (#2)
Parsing addresses extracted from Open Firmware isn't a simple matter. We
have various bits of code that try to do it in various place, including
some heuristics in prom.c that pre-parse addresses at boot and fill
device-nodes "addrs", but those are dodgy at best and I want to
deprecate them. So this patch introduces a new set of routines that
should be capable of parsing most types of addresses and translating
them into CPU physical addresses. It currently works for things on PCI
busses and ISA busses and should work on "standard" busses like the root
bus or the MacIO bus that don't put funky flags in addresses. If you
have other bus types that do use funky flags, you'll have to add new bus
type translators, which is fairly easy.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:46 +11:00
David Woodhouse
bcb05504ed [PATCH] ppc64 syscall_exit_work: call the save_nvgprs function, not its descriptor.
On Tue, 2005-11-15 at 18:52 +0000, David Woodhouse wrote:
> This cleanup patch speeds up the null syscall path on ppc64 by about 3%,
> and brings the ppc32 and ppc64 code slightly closer together.

Needs this unless your binutils, like mine, are clever enough to notice
my stupidity and fix it up automatically...

Spotted by Paul.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:42 +11:00
Paul Mackerras
c1189c9275 ppc: remove duplicate bseip.h
include/asm-ppc/bseip.h is a duplicate of arch/ppc/platforms/bseip.h
and is not referenced anywhere, so get rid of it.  Pointed out by
Marcelo Tosatti.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:38 +11:00
Paul Mackerras
d6a55504b3 powerpc: Update __NR_syscalls to account for SPU syscalls
A previous patch ended up not increasing __NR_syscalls to account
for the new SPU syscalls (probably my fault).

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:34 +11:00
Arnd Bergmann
8b3d6663c6 [PATCH] spufs: cooperative scheduler support
This adds a scheduler for SPUs to make it possible to use
more logical SPUs than physical ones are present in the
system.

Currently, there is no support for preempting a running
SPU thread, they have to leave the SPU by either triggering
an event on the SPU that causes it to return to the
owning thread or by sending a signal to it.

This patch also adds operations that enable accessing an SPU
in either runnable or saved state. We use an RW semaphore
to protect the state of the SPU from changing underneath
us, while we are holding it readable. In order to change
the state, it is acquired writeable and a context save
or restore is executed before downgrading the semaphore
to read-only.

From: Mark Nutter <mnutter@us.ibm.com>,
      Uli Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:30 +11:00
Mark Nutter
05b841174c [PATCH] spufs: add spu-side context switch code
Add the source code that is used to generate spu_save_dump.h and
spu_restore_dump.h. Since a full spu tool chain is needed to
generate these files, the default remains to use the shipped
versions in order to keep the number of tools for building the
kernel down.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:25 +11:00
Mark Nutter
7c038749d1 [PATCH] kernel-side context switch code for spufs
This adds the code needed to perform a context switch from
spufs, following the recommended 76-step sequence.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:21 +11:00
Mark Nutter
5473af049d [PATCH] spufs: switchable spu contexts
Add some infrastructure for saving and restoring the context of an
SPE. This patch creates a new structure that can hold the whole
state of a physical SPE in memory. It also contains code that
avoids races during the context switch and the binary code that
is loaded to the SPU in order to access its registers.

The actual PPE- and SPE-side context switch code are two separate
patches.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:16 +11:00
Arnd Bergmann
67207b9664 [PATCH] spufs: The SPU file system, base
This is the current version of the spu file system, used
for driving SPEs on the Cell Broadband Engine.

This release is almost identical to the version for the
2.6.14 kernel posted earlier, which is available as part
of the Cell BE Linux distribution from
http://www.bsc.es/projects/deepcomputing/linuxoncell/.

The first patch provides all the interfaces for running
spu application, but does not have any support for
debugging SPU tasks or for scheduling. Both these
functionalities are added in the subsequent patches.

See Documentation/filesystems/spufs.txt on how to use
spufs.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:12 +11:00
Heiko J Schick
d7a301033f [PATCH] powerpc: IBMEBUS bus support
This patch adds the necessary core bus support used by device drivers
that sit on the IBM GX bus on modern pSeries machines like the Galaxy
infiniband for example. It provide transparent DMA ops (the low level
driver works with virtual addresses directly) along with a simple bus
layer using the Open Firmware matching routines.

Signed-off-by: Heiko J Schick <schickhj@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:06 +11:00
David Woodhouse
401d1f029b [PATCH] syscall entry/exit revamp
This cleanup patch speeds up the null syscall path on ppc64 by about 3%,
and brings the ppc32 and ppc64 code slightly closer together.

The ppc64 code was checking current_thread_info()->flags twice in the
syscall exit path; once for TIF_SYSCALL_T_OR_A before disabling
interrupts, and then again for TIF_SIGPENDING|TIF_NEED_RESCHED etc after
disabling interrupts. Now we do the same as ppc32 -- check the flags
only once in the fast path, and re-enable interrupts if necessary in the
ptrace case.

The patch abolishes the 'syscall_noerror' member of struct thread_info
and replaces it with a TIF_NOERROR bit in the flags, which is handled in
the slow path. This shortens the syscall entry code, which no longer
needs to clear syscall_noerror.

The patch adds a TIF_SAVE_NVGPRS flag which causes the syscall exit slow
path to save the non-volatile GPRs into a signal frame. This removes the
need for the assembly wrappers around sys_sigsuspend(),
sys_rt_sigsuspend(), et al which existed solely to save those registers
in advance. It also means I don't have to add new wrappers for ppoll()
and pselect(), which is what I was supposed to be doing when I got
distracted into this...

Finally, it unifies the ppc64 and ppc32 methods of handling syscall exit
directly into a signal handler (as required by sigsuspend et al) by
introducing a TIF_RESTOREALL flag which causes _all_ the registers to be
reloaded from the pt_regs by taking the ret_from_exception path, instead
of the normal syscall exit path which stomps on the callee-saved GPRs.

It appears to pass an LTP test run on ppc64, and passes basic testing on
ppc32 too. Brief tests of ptrace functionality with strace and gdb also
appear OK. I wouldn't send it to Linus for 2.6.15 just yet though :)

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:49:01 +11:00
Kumar Gala
1cd8e50620 [PATCH] powerpc: moved ipic code to arch/powerpc
Moved 83xx and QUICC Engine interrupt handling code into arch/powerpc
as a precursor of getting 83xx sub-arch building in arch/powerpc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:48:57 +11:00
Michael Ellerman
3d1229d6ae [PATCH] powerpc: Merge kexec
This patch merges, to some extent, the PPC32 and PPC64 kexec implementations.

We adopt the PPC32 approach of having ppc_md callbacks for the kexec functions.
The current PPC64 implementation becomes the "default" implementation for PPC64
which platforms can select if they need no special treatment.

I've added these default callbacks to pseries/maple/cell/powermac, this means
iSeries no longer supports kexec - but it never worked anyway.

I've renamed PPC32's machine_kexec_simple to default_machine_kexec, inline with
PPC64. Judging by the comments it might be better named machine_kexec_non_of,
or something, but at the moment it's the only implementation for PPC32 so it's
the "default".

Kexec requires machine_shutdown(), which is in machine_kexec.c on PPC32, but we
already have in setup-common.c on powerpc. All this does is call
ppc_md.nvram_sync, which only powermac implements, so instead make
machine_shutdown a ppc_md member and have it call core99_nvram_sync directly
on powermac.

I've also stuck relocate_kernel.S into misc_32.S for powerpc.

Built for ARCH=ppc, and 32 & 64 bit ARCH=powerpc, with KEXEC=y/n. Booted on
P5 LPAR and successfully kexec'ed.

Should apply on top of 493f25ef40.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:48:52 +11:00
Adrian Bunk
afcc2472d8 [PATCH] PPC_PREP: remove unneeded exports
This patch removes the EXPORT_SYMBOL'ed but completely unused variable
ucSystemType and removes the unneeded EXPORT_SYMBOL(_prep_type).

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Tom Rini <trini@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-01-09 14:48:47 +11:00
Linus Torvalds
b9abaa3fb7 Merge git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2006-01-07 11:29:51 -08:00
Linus Torvalds
8995b161eb Merge master.kernel.org:/home/rmk/linux-2.6-arm 2006-01-07 10:45:22 -08:00
Linus Torvalds
cc918c7ab7 Merge master.kernel.org:/home/rmk/linux-2.6-serial 2006-01-07 10:44:22 -08:00
Linus Torvalds
f9c5d0451b Merge master.kernel.org:/home/rmk/linux-2.6-mmc 2006-01-07 10:43:40 -08:00
Knut Petersen
d354d9afe9 [PATCH] fbcon: don´t call set_par() in fbcon_init() if vc_mode == KD_GRAPHICS
Nothing prevents a user to modprobe a framebuffer driver from e.g.  the
xterm prompt.  As a result, the set_par() function of the driver will be
called from fbcon_init().

This is fatal as a lot of X / framebuffer combinations are unable to
recover from set_par() reprogramming the graphics controller in
KD_GRAPHICS mode.

It is also unnecessary as the set_par() function will be called during a
switch to KD_TEXT anyway.  Because of this no side effects are possible.

Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-07 10:39:34 -08:00
Russell King
fe5dd7c73d [ARM] byteorder.h needs linux/compiler.h
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 16:55:50 +00:00
Vernon Mauery
736ce43295 Input: ibmasm - convert to dynamic input_dev allocation
Update the ibmasm driver to use the dynamic allocation of input_dev
structs to work with the sysfs subsystem.

Vojtech: Fixed some problems/bugs in the patch.
Dmitry: Fixed some more.

Signed-off-by: Vernon Mauery <vernux@us.ibm.com>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2006-01-07 11:35:05 -05:00
Russell King
f8ce25476d [ARM] Move asm/hardware/clock.h to linux/clk.h
This is needs to be visible to other architectures using the AMBA
bus and peripherals.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 16:15:52 +00:00
Russell King
de1d815fcc [ARM] Move AMBA bus code to drivers/amba/
Make the AMBA bus code visible to other architectures.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 14:54:15 +00:00
Russell King
123656d4cc Merge with Linus' kernel. 2006-01-07 14:40:05 +00:00
Russell King
a62c80e559 [ARM] Move AMBA include files to include/linux/amba/
Since the ARM AMBA bus is used on MIPS as well as ARM, we need
to make the bus available for other architectures to use.  Move
the AMBA include files from include/asm-arm/hardware/ to
include/linux/amba/

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 13:52:45 +00:00
Andre McCurdy
6351610d69 [ARM] 3239/1: Add ARM optimised swab32
Patch from Andre McCurdy

Replaces generic swab32 routine with a more ARM friendly version.
Reduces kernel text size by approx 1200 bytes when compiled with
3.4.4 and approx 2400 bytes with 4.0.2

Probably some performance benefit as well.

Signed-off-by: Andre McCurdy <armccurdy@yahoo.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 11:39:20 +00:00
Richard Purdie
2c041f4b9b [ARM] 3235/1: SharpSL PM: Fix a gcc4 build error
Patch from Richard Purdie

Fix a gcc4 build error (incomplete element type) in the pxa SharpSL
PM code.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 11:12:26 +00:00
Pavel Pisa
f99c89297c [ARM] 3232/1: i.MX Frame Buffer undeclared "dev" variable fix
Patch from Pavel Pisa

Correction of the code broken by update
whole-tree platform devices update.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-07 10:44:32 +00:00
Borislav Petkov
f9a204e1de [ACPI] remove Kconfig "default y" for laptop drivers
Signed-off-by: Borislav Petkov <petkov@uni-muenster.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
2006-01-07 05:11:08 -05:00
Randy Dunlap
d758a8fa8c [ACPI] fix kernel-doc warnings in acpi/scan.c
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
2006-01-07 05:05:31 -05:00
Len Brown
add5b5ee99 Auto-update from upstream 2006-01-07 02:05:40 -05:00
David S. Miller
0aec63e67c [PATCH] Fix posix-cpu-timers sched_time accumulation
I've spent the past 3 days digging into a glibc testsuite failure in
current CVS, specifically libc/rt/tst-cputimer1.c The thr1 and thr2
timers fire too early in the second pass of this test.  The second
pass is noteworthy because it makes use of intervals, whereas the
first pass does not.

All throughout the posix-cpu-timers.c code, the calculation of the
process sched_time sum is implemented roughly as:

	unsigned long long sum;

	sum = tsk->signal->sched_time;
	t = tsk;
	do {
		sum += t->sched_time;
		t = next_thread(t);
	} while (t != tsk);

In fact this is the exact scheme used by check_process_timers().

In the case of check_process_timers(), current->sched_time has just
been updated (via scheduler_tick(), which is invoked by
update_process_times(), which subsequently invokes
run_posix_cpu_timers()) So there is no special processing necessary
wrt. that.

In other contexts, we have to allot for the fact that tsk->sched_time
might be a bit out of date if we are current.  And the
posix-cpu-timers.c code uses current_sched_time() to deal with that.

Unfortunately it does so in an erroneous and inconsistent manner in
one spot which is what results in the early timer firing.

In cpu_clock_sample_group_locked(), it does this:

		cpu->sched = p->signal->sched_time;
		/* Add in each other live thread.  */
		while ((t = next_thread(t)) != p) {
			cpu->sched += t->sched_time;
		}
		if (p->tgid == current->tgid) {
			/*
			 * We're sampling ourselves, so include the
			 * cycles not yet banked.  We still omit
			 * other threads running on other CPUs,
			 * so the total can always be behind as
			 * much as max(nthreads-1,ncpus) * (NSEC_PER_SEC/HZ).
			 */
			cpu->sched += current_sched_time(current);
		} else {
			cpu->sched += p->sched_time;
		}

The problem is the "p->tgid == current->tgid" test.  If "p" is
not current, and the tgids are the same, we will add the process
t->sched_time twice into cpu->sched and omit "p"'s sched_time
which is very very very wrong.

posix-cpu-timers.c has a helper function, sched_ns(p) which takes care
of this, so my fix is to use that here instead of this special tgid
test.

The fact that current can be one of the sub-threads of "p" points out
that we could make things a little bit more accurate, perhaps by using
sched_ns() on every thread we process in these loops.  It also points
out that we don't use the most accurate value for threads in the group
actively running other cpus (and this is mentioned in the comment).

But that is a future enhancement, and this fix here definitely makes
sense.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 20:23:04 -08:00