The previous revert of 0c07ee38c9 left
out the mwait disable condition for AMD family 10H/11H CPUs.
Andreas Herrman said:
It depends on the CPU. For AMD CPUs that support MWAIT this is wrong.
Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings then
depend on a clock divisor and current Pstate of the core.
If all cores of a processor are in halt state (C1) the processor can
enter the C1E (C1 enhanced) state. If mwait is used this will never
happen.
Thus HLT saves more power than MWAIT here.
It might be best to switch off the mwait flag for these AMD CPU
families like it was introduced with commit
f039b75471 (x86: Don't use MWAIT on AMD
Family 10)
Re-add the AMD families 10H/11H check and disable the mwait usage for
those.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
pat_disable() is __init, which means it goes away after booting is complete.
Unfortunately it is used by the hotplug code if the machine is not
pat-capable, causing a crash.
Fix by marking pat_disable() as __cpuinit.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Vegard Nossum reports:
| powertop shows between 200-400 wakeups/second with the description
| "<kernel IPI>: Rescheduling interrupts" when all processors have load (e.g.
| I need to run two busy-loops on my 2-CPU system for this to show up).
|
| The bisect resulted in this commit:
|
| commit 0c07ee38c9
| Date: Wed Jan 30 13:33:16 2008 +0100
|
| x86: use the correct cpuid method to detect MWAIT support for C states
remove the functional effects of this patch and make mwait unconditional.
A future patch will turn off mwait on specific CPUs where that causes
power to be wasted.
Bisected-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
[POWERPC] macintosh: Replace deprecated __initcall with device_initcall
[POWERPC] cell: Fix section mismatches in io-workarounds code
[POWERPC] spufs: Fix compile error
[POWERPC] Fix uninitialized variable bug in copy_{to|from}_user
[POWERPC] Add null pointer check to of_find_property
[POWERPC] vmemmap fixes to use smaller pages
[POWERPC] spufs: Fix pointer reference in find_victim
[POWERPC] 85xx: SBC8548 - Add flash support and HW Rev reporting
[POWERPC] 85xx: Fix some sparse warnings for 85xx MDS
[POWERPC] 83xx: Enable DMA engine on the MPC8377 MDS board.
[POWERPC] 86xx: mpc8610_hpcd: fix second serial port
[POWERPC] 86xx: mpc8610_hpcd: add support for NOR and NAND flashes
[POWERPC] 85xx: Add 8568 PHY workarounds to board code
[POWERPC] 86xx: mpc8610_hpcd: use ULI526X driver for on-board ethernet
The patch aims to fix a performance issue for the syscall
personality(PER_LINUX32).
On IA-64 box, the syscall personality (PER_LINUX32) has poor performance
because it failed to find the Linux/x86 execution domain. Then it tried
to load the kernel module however it failed always and it used the default
execution domain PER_LINUX instead. Requesting kernel modules is very
expensive. It caused the performance issue. (see the function
lookup_exec_domain in kernel/exec_domain.c).
To resolve the issue, execution domain Linux/x86 is always registered in
initialization time for IA-64 architecture.
Signed-off-by: Xiaolan Huang <xiaolan.huang@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
[S390] show_interrupts: prevent cpu hotplug when walking cpu_online_map.
[S390] smp: __smp_call_function_map vs cpu_online_map fix.
[S390] tape: Use ccw_dev_id to build cdev_id.
[S390] dasd: fix timeout handling in interrupt handler
[S390] s390dbf: Use const char * for dbf name.
[S390] dasd: Use const in busid functions.
[S390] blacklist.c: removed duplicated include
[S390] vmlogrdr: module initialization function should return negative errors
[S390] sparsemem vmemmap: initialize memmap.
[S390] Remove last traces of cio_msg=.
[S390] cio: Remove CCW_CMD_SUSPEND_RECONN in front of CCW_CMD_SET_PGID.
Surround all the code withing show_interrupts() with
get/put_online_cpus() to prevent strange results wrt cpu hotplug.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Both smp_call_function() and __smp_call_function_map() access
cpu_online_map. Both functions run with preemption disabled which
protects for cpus going offline. However new cpus can be added and
therefore the cpu_online_map can change unexpectedly.
So use the call_lock to protect against changes to the cpu_online_map
in start_secondary() and all smp_call_* functions.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
We should use const char * for passing the name of the debug feature
around since it will not be changed.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Let's just use the generic vmmemmap_alloc_block() function which
always returns initialized memory.
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The functions time_before, time_before_eq, time_after, and time_after_eq are
more robust for comparing jiffies against other values.
So use the time_after() macro, defined in linux/jiffies.h, which deals with
wrapping correctl
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: S.Caglar Onur <caglar@pardus.org.tr>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
show_mem() has no need to print the amount of free swap space manually because
show_free_areas() does this already and is called by the former.
The two outputs only differ in text formatting:
printk("Free swap = %lukB\n", ...);
printk("Free swap: %6ldkB\n", ...);
Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
This trivial patch fixes the following section warnings on PARISC:
> WARNING: vmlinux.o (.text.1): unexpected section name.
>The (.[number]+) following section name are ld generated and not expected.
> Did you forget to use "ax"/"aw" in a .S file?
> Note that for example <linux/init.h> contains
> section definitions for use in .S files.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Fix following warnings:
WARNING: arch/powerpc/platforms/cell/built-in.o(.devinit.text+0x9c): Section mismatch in reference from the function .cell_setup_phb() to the function .init.text:.iowa_register_bus()
WARNING: arch/powerpc/platforms/cell/built-in.o(.devinit.text+0xa4): Section mismatch in reference from the function .cell_setup_phb() to the function .init.text:.io_workaround_init()
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Paul Mackerras <paulus@samba.org>
With CONFIG_VIRT_CPU_ACCOUNTING disabled, I got the following error:
linux-2.6/arch/powerpc/platforms/cell/spufs/file.c: In function 'spu_switch_log_notify':
linux-2.6/arch/powerpc/platforms/cell/spufs/file.c:2542: error: implicit declaration of function 'get_tb'
make[4]: *** [arch/powerpc/platforms/cell/spufs/file.o] Error 1
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This changes vmemmap to use a different region (region 0xf) of the
address space, and to configure the page size of that region
dynamically at boot.
The problem with the current approach of always using 16M pages is that
it's not well suited to machines that have small amounts of memory such
as small partitions on pseries, or PS3's.
In fact, on the PS3, failure to allocate the 16M page backing vmmemmap
tends to prevent hotplugging the HV's "additional" memory, thus limiting
the available memory even more, from my experience down to something
like 80M total, which makes it really not very useable.
The logic used by my match to choose the vmemmap page size is:
- If 16M pages are available and there's 1G or more RAM at boot,
use that size.
- Else if 64K pages are available, use that
- Else use 4K pages
I've tested on a POWER6 (16M pages) and on an iSeries POWER3 (4K pages)
and it seems to work fine.
Note that I intend to change the way we organize the kernel regions &
SLBs so the actual region will change from 0xf back to something else at
one point, as I simplify the SLB miss handler, but that will be for a
later patch.
Signed-off-by: Paul Mackerras <paulus@samba.org>
If victim (not ctx) is in spu_run, add victim to rq.
Signed-off-by: Luke Browning <lukebrowning@us.ibm.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
sparc64: Use a TS_RESTORE_SIGMASK
lmb: Make lmb debugging more useful.
lmb: Fix inconsistent alignment of size argument.
sparc: Fix mremap address range validation.
Add a common hex array in hexdump.c so everyone can use it.
Add a common hi/lo helper to avoid the shifting masking that is
done to get the upper and lower nibbles of a byte value.
Pull the pack_hex_byte helper from kgdb as it is opencoded many
places in the tree that will be consolidated.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Jason Wessel <jason.wessel@windriver.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>
Fix initialization of framebuffer not calling ioremap_writecombine() function
and not using internal SRAM for at91sam9rl.
This is a little rework of the "Don't initialize a pre-allocated framebuffer"
patch that corrects the call to ioremap_writecombine() function.
It also cuts the use of internal SRAM for at91sam9rl : it is a bit small
for a framebuffer.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
acpi_unregister_gsi() should "undo" what acpi_register_gsi() does.
On systems that have legacy interrupts, acpi_unregister_gsi erroneously calls
iosapci_unregister_intr() which is wrong to do and causes a loud warning.
acpi_unregister_gsi() should just return in these cases.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
There is only palinfo_handle_smp as (indirect) user of palinfo_smp_call (by
way of smp_call_function_single) and surely palinfo_handle_smp never pass
NULL as parameter for info.
Signed-off-by: Simon Holm Thøgersen <odie@cs.aau.dk>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Fix a typo, and coding style cleanups for pfm_handle_work().
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This patch does:
- make comment at next to resched check more robust
- move "re-check" comments to next to where change predicate regs
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
[Bug-fix for "[BUG?][2.6.25-mm1] sleeping during IRQ disabled"]
This patch does:
- enable interrupts before calling schedule() as same as others, ex. x86
- enable interrupts during ia64_do_signal() and ia64_sync_krbs()
- do_notify_resume_user() is still called with interrupts disabled, since
we can take short path of fsys_mode if-statement quickly.
- pfm_handle_work() is also called with interrupts disabled, since
it can deal interrupt mask within itself.
- fix/add some comments/notes
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
The sequence executed in check_sal_cache_flush:
- pend a timer interrupt
- call SAL_CACHE_FLUSH
- see if interrupt is still pending
can hang HP machines with buggy SAL_CACHE_FLUSH implementations.
Provide a kernel command-line argument to allow users skip this
check if desired. Using this parameter will force ia64_sal_cache_flush
to call ia64_pal_cache_flush() instead of SAL_CACHE_FLUSH.
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Some IA64 machines map all cell-local memory above 4 GB (32 bit limit).
However, in most cases, the kernel needs some memory below that limit that is
DMA-capable. So in this machine configuration, the crashkernel will be reserved
above 4 GB.
For machines that use SWIOTLB implementation because they lack an I/O MMU
the low memory is required by the SWIOTLB implementation. In that case,
it doesn't make sense to reserve the crashkernel at all because it's unusable
for kdump.
A special case is the "hpzx1" machine vector. In theory, it has a I/O MMU, so
it can be booted above 4 GB. However, in the kdump case that is not possible
because of changeset 51b58e3e26:
On HP zx1 machines, the 'machvec=dig' parameter is needed for the kdump
kernel to avoid problems with the HP sba iommu. The problem is that during
the boot of the kdump kernel, the iommu is re-initialized, so in-flight DMA
from improperly shutdown drivers causes an IOTLB miss which leads to an
MCA. With kdump, the idea is to get into the kdump kernel with as little
code as we can, so shutting down drivers properly is not an option.
The workaround is to add 'machvec=dig' to the kdump kernel boot parameters.
This makes the kdump kernel avoid using the sba iommu altogether, leaving
the IOTLB intact. Any ongoing DMA falls harmlessly outside the kdump
kernel. After the kdump kernel reboots, all devices will have been
shutdown properly and DMA stopped.
This patch pushes that functionality into the sba iommu initialization
code, so that users won't have to find the obscure documentation telling
them about 'machvec=dig'.
This means that also for hpzx1 it's not possible to boot when all
memory is above the 4 GB limit. So the only machine vectors that can handle
this case are "sn2" and "uv".
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This patch adds the basic IA64 machvec infrastructure to support
the SGI "UV" platform.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
ACPI/PCI: another multiple _OSC memory leak fix
x86/PCI: X86_PAT & mprotect
PCI: enable nv_msi_ht_cap_quirk for ALi bridges
PCI: Make the intel-iommu_wait_op macro work when jiffies are not running
ACPI/PCI: handle multiple _OSC
ACPI/PCI: handle multiple _OSC
x86/PCI: fix broken ISA DMA
PCI ACPI: fix uninitialized variable in __pci_osc_support_set
The user_regset_view table for the 32-bit regsets on the 64-bit build had
the wrong sizes for the FP regsets. This bug had no user-visible effect
(just on kernel modules using the user_regset interfaces and the like).
But the fix is trivial and risk-free.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
fix this warning:
arch/x86/mm/pat.c: In function `phys_mem_access_prot_allowed':
arch/x86/mm/pat.c:558: warning: long long unsigned int format, long
unsigned int arg (arg 6)
arch/x86/mm/pat.c: In function `map_devmem':
arch/x86/mm/pat.c:580: warning: long long unsigned int format, long
unsigned int arg (arg 6)
Signed-off-by: D Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix this symbol export problem:
Building modules, stage 2.
MODPOST 193 modules
ERROR: "csum_partial" [fs/reiserfs/reiserfs.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2
This is due to a known weakness of symbol exports: if a symbol's
only in-core user is an EXPORT_SYMBOL from a lib-y section, the
symbol is not linked in.
The solution is to move the export to x8664_ksyms_64.c - but the real
solution would be to fix kbuild.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/setup_64.c:954: warning: passing argument 2 of 'set_bit' from incompatible pointer type
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
After resume on a 2cpu laptop, kernel builds collapse with a sed hang,
sh or make segfault (often on 20295564), real-time signal to cc1 etc.
Several hurdles to jump, but a manually-assisted bisect led to -rc1's
d2bcbad5f3 x86: do not zap_low_mappings
in __smp_prepare_cpus. Though the low mappings were removed at bootup,
they were left behind (with Global flags helping to keep them in TLB)
after resume or cpu online, causing the crashes seen.
Reinstate zap_low_mappings (with local __flush_tlb_all) for each cpu_up
on x86_32. This used to be serialized by smp_commenced_mask: that's now
gone, but a low_mappings flag will do. No need for native_smp_cpus_done
to repeat the zap: let mem_init zap BSP's low mappings just like on UP.
(In passing, fix error code from native_cpu_up: do_boot_cpu returns a
variety of diagnostic values, Dprintk what it says but convert to -EIO.
And save_pg_dir separately before zap_low_mappings: doesn't matter now,
but zapping twice in succession wiped out resume's swsusp_pg_dir.)
That worked well on the duo and one quad, but wouldn't boot 3rd or 4th
cpu on P4 Xeon, oopsing just after unlock_ipi_call_lock. The TLB flush
IPI now being sent reveals a long-standing bug: the booting cpu has its
APIC readied in smp_callin at the top of start_secondary, but isn't put
into the cpu_online_map until just before that unlock_ipi_call_lock.
So native_smp_call_function_mask to online cpus would send_IPI_allbutself,
including the cpu just coming up, though it has been excluded from the
count to wait for: by the time it handles the IPI, the call data on
native_smp_call_function_mask's stack may well have been overwritten.
So fall back to send_IPI_mask while cpu_online_map does not match
cpu_callout_map: perhaps there's a better APICological fix to be
made at the start_secondary end, but I wouldn't know that.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Some versions of X used the mprotect workaround to change caching type from UC
to WB, so that it can then use mtrr to program WC for that region [1]. Change
the mmap of pci space through /sys or /proc interfaces from UC to UC_MINUS.
With this change, X will not need to use mprotect workaround to get WC type
since the MTRR mapping type will be honored.
The bug in mprotect that clobbers PAT bits is fixed in a follow on patch. So,
this X workaround will stop working as well.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Rene Herman reported:
> commit 8779f2fc3b
>
> "x86: don't try to allocate from DMA zone at first"
>
> breaks all of ISA DMA. Or all of ALSA ISA DMA at least. All
> ISA soundcards are silent following that commit -- no error
> messages, everything appears fine, just silence.
That patch is buggy. We had an implicit assumption that
dev = NULL for ISA devices that require 24bit DMA.
The recent work on x86 dma_alloc_coherent() breaks the ISA DMA buffer
allocation, which is represented by "dev = NULL" and requires 24bit
DMA implicitly.
Bisected-by: Rene Herman <rene.herman@keyaccess.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Include the missing kcrctab and kcrctab_unused sections into the m68knommu
linker script.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PA-RISC to aid debugging prints out the zonelists setup by the system. A
bad call to node_zonelist() breaks at compile-time. This patch fixes it.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This would appear to be the last reference to TOPDIR in the entire tree, after
which i'm guessing that variable can be dropped.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As the subject says this patch adds the support for kernel preemption on
m68knommu Coldfire. I thing the same changes could be applied to 68360 &
68328 but since I don't have the HW, I don't touch it. Kconfig enables the
preemption item only on coldfire.
This is a missing chunk from Sebastian's original patch that I lost from the
first submission.
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Alarm delivery could be noticably late in the !CONFIG_NOHZ case because lost
ticks weren't being taken into account. This is now treated more carefully,
with the time between ticks being calculated and the appropriate number of
ticks delivered to the timekeeping system.
Cc: Nix <nix@esperi.org.uk>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Give random.c a style workover while I'm changing it.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The random driver would essentially hang if the host's /dev/random returned
-EAGAIN. There was a test of need_resched followed by a schedule inside the
loop, but that didn't help and it's the wrong way to work anyway.
The right way is to ask for an interrupt when there is input available from
the host and handle it then rather than polling.
Now, when the host's /dev/random returns -EAGAIN, the driver asks for a wakeup
when there's randomness available again and sleeps. The interrupt routine
just wakes up whatever processes are sleeping on host_read_wait.
There is an atomic_t, host_sleep_count, which counts the number of processes
waiting for randomness. When this reaches zero, the interrupt is disabled.
An added complication is that async I/O notification was only recently added
to /dev/random (by me), so essentially all hosts will lack it. So, we use the
sigio workaround here, which is to have a separate thread poll on the
descriptor and send an interrupt when there is input on it. This mechanism is
activated when a process gets -EAGAIN (activating this multiple times is
harmless, if a bit wasteful) and deactivated by the last process still
waiting.
The module name was changed from "random" to "hw_random" in order for udev to
recognize it.
The sigio workaround needed some changes. sigio_broken was added for cases
when we know that async notification doesn't work. This is now called from
maybe_sigio_broken, which deals with pts devices.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
