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2006-02-14[PATCH] hrtimer: round up relative start time on low-res archesIngo Molnar
CONFIG_TIME_LOW_RES is a temporary way for architectures to signal that they simply return xtime in do_gettimeoffset(). In this corner-case we want to round up by resolution when starting a relative timer, to avoid short timeouts. This will go away with the GTOD framework. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-13[PATCH] sys_newfstatat -> sys_fstatat64Kyle McMartin
parisc defines ARCH_WANT_STAT64, so we want to use fstatat64. It does not appear that it needs to be ENTRY_COMP, because struct stat64 is the same on both 32-bit and 64-bit (unlike on other platforms which did define a compat_sys_fstatat64.) Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-08[PARISC] Stub out pselect6/ppoll until TIF_RESTORE_SIGMASK is doneKyle McMartin
Swap out pselect6/ppoll for ni_syscall for now. We also have to switch the macro to ENTRY_SAME since compat_sys_ni_syscall does not exist. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-02-07[PATCH] sys_hpux: fix strlen_user() raceKyle McMartin
Userspace can alter the string after the kernel has run strlen_user(). Also: the strlen_user() return value includes the \0, so fix that. Also: handle EFAULT from strlen_user(). It's unlikely anyone is using this code. Very, very unlikely. If I remember correctly, CONFIG_HPUX turns this code on, but one would actually need CONFIG_BINFMT_SOM to load a binary that could cause a problem, and BINFMT_SOM has had an #error in it for quite some time. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-30[PARISC] New syscalls (inotify, *at, pselect6/ppoll, migrate_pages)Kyle McMartin
Wire up some new syscalls that have been merged upstream, o inotify o openat et al o pselect6/ppoll o migrate_pages Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-29[PARISC] Simplify DISCONTIGMEM in KconfigKyle McMartin
parisc was previously displaying both the mm/Kconfig memory model menu, and its own prompt. Remove prompt and have CONFIG_64BIT toggle between DISCONTIGMEM and FLATMEM. Also remove the EXPERIMENTAL from discontigmem support... It's been running fine for months (years?) now. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Arch-specific compat signalsKyle McMartin
Add enough arch-specific compat signals code to enable parisc64 to compile and boot out of the mainline tree. There are likely still many dragons here, but this is a start to squashing the last big difference between the mainline tree and the parisc-linux tree. The remaining bugs can be squashed as they come up. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Use DEBUG_KERNEL to catch used-after-free __init dataHelge Deller
Use CONFIG_DEBUG_KERNEL to catch kernel code which tries to access __init data after it is freed. When CONFIG_DEBUG_KERNEL is not set this also cleans up a WARN_ON at boot time. Also remove some dead code from mm/init.c Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Add CONFIG_DEBUG_RODATA to protect read-only dataHelge Deller
Add the parisc version of the "mark rodata section read only" patches. Based on code from and Signed-off-by Arjan van de Ven <arjan@infradead.org>, Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@muc.de>, Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>. Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Remove {,un}lock_kernel from perf ioctlMatthew Wilcox
Remove the lock_kernel/unlock_kernel pair in the ioctl method. It plainly wasn't protecting anything. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Add chassis_power_off routineKyle McMartin
Define a chassis_power_off routine that machines which have a way to turn off the power supply can hook into. Formerly they were using pm_power_off, which is now being used by generic code. Make lasi.c use chassis_power_off instead of pm_power_off. Note, all machines need to call machine_power_off so that the switch can power off the machine, though halt -p may not necessarily be able to work properly on the machine. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Remove obsolete _hlt cruftKyle McMartin
Remove a bunch of obsolete code from process.c, these routines were likely imported from the i386 version of process.c when the port started. The routines are only used in floppy.c, which I seriously doubt will ever work on parisc, due to architectural assumptions. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Move pm_power_off export to process.cKyle McMartin
Move the EXPORT_SYMBOL() of pm_power_off from parisc_ksyms.c to the location of its definition in process.c Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Clean up compiler warning in pci.cHelge Deller
Avoid compiler warning for unused variables on 32bit kernels by conditionalizing the local variables on CONFIG_64BIT. PCI_HOST_ADDR() only uses the hba argument on 64bit compiles. Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Use F_EXTEND() for COMMAND_GLOBALKyle McMartin
Instead of wrapping the define of COMMAND_GLOBAL in #ifdef __LP64__ use the F_EXTEND() macro defined in asm/io.h, which is the preferred way of extending mmio space addresses for either 32 or 64 bit machines. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Fix floating point invalid exception trap handlerJames Bottomley
Fix our trap handler to issue the correct floating point exception for both types of invalid trap. Signed-off-by: James Bottomley <jejb@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Drop unused do_check_pgt_cache()Helge Deller
Drop the unused do_check_pgt_cache routine from mm/init.c and its prototype in asm/pgalloc.h Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Remove unnecessary extern declarations from asm/pci.hGrant Grundler
Remove two unnecessary extern declarations from asm/pci.h. They collide with what gcc4.0 assumed was static (and should be static). Found by Joel Soete. Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Use kzalloc and other janitor-style cleanupsHelge Deller
Helge, o Convert a bunch of kmalloc/memset uses to kzalloc. o pci.c: Add some __read_mostly annotations. o pci.c: Move constant pci_post_reset_delay to asm/pci.h o grfioctl.h: Add A4450A to comment of CRT_ID_VISUALIZE_EG. o Add some consts to perf.c/perf_images.h Matthew, o sticore.c: Add some consts to suppress compile warnings. Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-22[PARISC] Update b180_defconfigMatthew Wilcox
Update b180_defconfig to be more usable on other similar machines. Enabling Lasi 82596, Harmony, Mux console, CCIO, HPPB, etc., means this config is suitable for not only BXXX machines, but also CXXX and JXXX class machines. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-21[PARISC] Make flush_tlb_all_local take a void *Matthew Wilcox
Make flush_tlb_all_local take a void * so it doesn't have to be cast when using on_each_cpu(). This becomes a problem when on_each_cpu is a macro. Also remove the prototype of flush_tlb_all_local from .c files. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-18[PATCH] e1000: Added disable packet split capabilityJesse Brandeburg
Adds the ability to disability packet split at compile time and use the legacy receive path on PCI express hardware. Made this a CONFIG option and modified the Kconfig, to reflect the new option. Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: John Ronciak <john.ronciak@intel.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
2006-01-13[PATCH] Add parisc_bus_type probe and remove methodsRussell King
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Matthew Wilcox <matthew@wil.cx> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-01-12[PATCH] parisc: task_stack_page(), task_thread_info()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-11[PATCH] capable/capability.h (arch/)Randy Dunlap
arch: Use <linux/capability.h> where capable() is used. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10[PARISC] Use STABS_DEBUG macro from vmlinux.lds.hMatthew Wilcox
Cleanup vmlinux.lds.S by using STABS_DEBUG macro from vmlinux.lds.h instead of repeating the sections. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Fix Dino reporting on J2240Matthew Wilcox
Fix Dino reporting on J2240. This particular machine thought it had a Cujo. Also add J2240 Dino chip to the hp_hardware_list. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Fix BLK_BOUNCE_HIGH on parisc by initializing max_low_pfnGrant Grundler
max_low_pfn was not being set in arch/parisc/mm/init.c, causing severe problems whenever anything tried to use BLK_BOUNCE_HIGH. Set it to max_pfn like other similar architectures do. Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Fix GSC graphics cards with 64MB regionsMatthew Wilcox
Make knapps work with its 64MB gfx card. I probably just broke another machine in the process, but assuming 64MB when 64MB aligned is probably safer than assuming 32MB all the time. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Fix and cleanup ioremap.c to work with 4level-fixup.hKyle McMartin
Fixup ioremap a bit. It seems to work on 32-bit kernels, but fails miserably on the first ioremapped access on 64-bit kernels. Also, having STI enabled causes it to fail. Probably because we're passing an ioremapped region to a real-mode STI call... Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Make local cache flushes take a void *Matthew Wilcox
Make flush_data_cache_local, flush_instruction_cache_local and flush_tlb_all_local take a void * so they don't have to be cast when using on_each_cpu(). This becomes a problem when on_each_cpu is a macro (as it is in current -mm). Also move the prototype of flush_tlb_all_local into tlbflush.h and remove its declaration from .c files. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PARISC] Add __read_mostly section for pariscHelge Deller
Flag a whole bunch of things as __read_mostly on parisc. Also flag a few branches as unlikely() and cleanup a bit of code. Signed-off-by: Helge Deller <deller@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-01-10[PATCH] sanitize building of fs/compat_ioctl.cChristoph Hellwig
Now that all these entries in the arch ioctl32.c files are gone [1], we can build fs/compat_ioctl.c as a normal object and kill tons of cruft. We need a special do_ioctl32_pointer handler for s390 so the compat_ptr call is done. This is not needed but harmless on all other architectures. Also remove some superflous includes in fs/compat_ioctl.c Tested on ppc64. [1] parisc still had it's PPP handler left, which is not fully correct for ppp and besides that ppp uses the generic SIOCPRIV ioctl so it'd kick in for all netdevice users. We can introduce a proper handler in one of the next patch series by adding a compat_ioctl method to struct net_device but for now let's just kill it - parisc doesn't compile in mainline anyway and I don't want this to block this patchset. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10[PATCH] move rtc compat ioctl handling to fs/compat_ioctl.cChristoph Hellwig
This patch implements generic handling of RTC_IRQP_READ32, RTC_IRQP_SET32, RTC_EPOCH_READ32 and RTC_EPOCH_SET32 in fs/compat_ioctl.c. It's based on the x86_64 code which needed a little massaging to be endian-clean. parisc used COMPAT_IOCTL or generic w_long handlers for these whichce is wrong and can't work because the ioctls encode sizeof(unsigned long) in their ioctl number. parisc also duplicated COMPAT_IOCTL entries for other rtc ioctls which I remove in this patch, too. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Matthew Wilcox <matthew@wil.cx> Acked-by: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] tiny: Make *[ug]id16 support optionalMatt Mackall
Configurable 16-bit UID and friends support This allows turning off the legacy 16 bit UID interfaces on embedded platforms. text data bss dec hex filename 3330172 529036 190556 4049764 3dcb64 vmlinux-baseline 3328268 529040 190556 4047864 3dc3f8 vmlinux From: Adrian Bunk <bunk@stusta.de> UID16 was accidentially disabled for !EMBEDDED. Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-17[PARISC] Remove unused variable in signal.cGrant Grundler
Remove unused variable "struct siginfo si" in signal.c Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] remove drm compat ioctls handlersChristoph Hellwig
Remove drm compat_ioctl handlers. The drm drivers have proper compat_ioctl methods these days. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] move PA perf driver over to ->compat_ioctlChristoph Hellwig
Move PA perf driver over to ->compat_ioctl. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Randolph Chung <tausq@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Fix some compile problems in ptrace.cMatthew Wilcox
Fix some compile problems: - ret wasn't being initialised in all code paths - I'm pretty sure 'goto out' should have been 'goto out_tsk' Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Improve the error message when we get a clashing mod pathMatthew Wilcox
Improve the error message when we get a clashing mod path, and actually display the IODC data and path for the conflicting device. Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Return PDC_OK when alloc_pa_dev fails to enumerate all devicesMatthew Wilcox
Return PDC_OK when device registration fails so that we enumerate all subsequent devices, even when we get two devices with the same hardware path (which should never happen, but does with at least one revision of rp8400 firmware). Signed-off-by: Matthew Wilcox <willy@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Document some register usages in assembly filesCarlos O'Donell
Document clobbers and args in entry.S and syscall.S. entry.S: Add comment to indicate that cr27 may recycle and EDEADLOCK detection is not 100% correct. Since this is only enabled when using ENABLE_LWS_DEBUG, the user is warned by the comment. Signed-off-by: Carlos O'Donell <carlos@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Make redirecting irq messages less noisyRyan Bradetich
Make the "redirecting irq" message to not display on the console by setting the severity to KERN_DEBUG. The console was basically unusable. Signed-off-by: Ryan Bradetich <rbrad@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] irq_affinityp[] only available for SMP buildsGrant Grundler
irq_affinityp[] only available for SMP builds, make code that uses it conditional on CONFIG_SMP. Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Add IRQ affinitiesJames Bottomley
This really only adds them for the machines I can check SMP on, which is CPU interrupts and IOSAPIC (so not any of the GSC based machines). With this patch, irqbalanced can be used to maintain irq balancing. Unfortunately, irqbalanced is a bit x86 centric, so it doesn't do an incredibly good job, but it does work. Signed-off-by: James Bottomley <jejb@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Fix uniprocessor build by dummying smp_send_all_nop()Kyle McMartin
Since irq.c uses smp_send_all_nop, we must define it for UP builds as well. Make it a static inline so it gets optimized away. This forces irq.c to include <asm/smp.h> though. Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Fix our interrupts not to use smp_call_functionJames Bottomley
Fix our interrupts not to use smp_call_function On K and D class smp, the generic code calls this under an irq spinlock, which causes the WARN_ON() message in smp_call_function() (and is also illegal because it could deadlock). The fix is to use a new scheme based on the IPI_NOP. Signed-off-by: James Bottomley <jejb@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Disable nesting of interruptsGrant Grundler
Disable nesting of interrupts - still has holes The offending sequence starts out like this: 1) take external interrupt 2) set_eiem() to only allow TIMER_IRQ; local interrupts still disabled 3) read the EIRR to get a "list" of pending interrupts 4) clear EIRR of pending interrupts we intend to handle 5) call __do_IRQ() to handle IRQ. 6) handle_IRQ_event() enables local interrupts (I-Bit) 7) take a timer interrupt 8) read EIRR to get a new list of pending interrupts 9) clear EIRR of pending interrupts we just read 10) handle pending interrupts found in (8) 11) set_eiem(cpu_eiem) and return [ TROUBLE! all enabled CPU IRQs are unmasked. } 12) handle remaining interrupts pending from (3) e.g. call __do_IRQ() -> handle_IRQ_event()..etc [ TROUBLE! call to handle_IRQ_event() can now enable *any* IRQ. } 13) set_eiem(cpu_eiem) and return The problem is we now get into ugly race conditions with Timer and IPI interrupts at this point. I'm not exactly sure what happens when things go wrong (perhaps nest calls to IPI or timer interrupt?). But I'm certain it's not good. This sequence will break sooner if (10) would accidentally leave interrupts enabled. I'm pretty sure the right answer is now to make cpu_eiem a per CPU variable since all external interrupts on parisc are per CPU. This means we will NOT need to send an IPI to every CPU in the system when enabling or disabling an IRQ since only one CPU needs to change it's EIEM. Thanks to James Bottomley for (once again) pointing out the problem. Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17[PARISC] Make sure timer and IPI execute with interrupts disabledJames Bottomley
Fix a longstanding smp bug The problem is that both the timer and ipi interrupts are being called with interrupts enabled, which isn't what anyone is expecting. The IPI issue has just started to show up by causing a BUG_ON in the slab debugging code. The timer issue never shows up because there's an eiem work around in our irq.c The fix is to label both these as SA_INTERRUPT which causes the generic irq code not to enable interrupts. I also suspect the smp_call_function timeouts we're seeing might be connected with the fact that we disable IPIs when handling any other type of interrupt. I've put a WARN_ON in the code for executing smp_call_function() with IPIs disabled. Signed-off-by: James Bottomley <jejb@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-09[PATCH] sched: resched and cpu_idle reworkNick Piggin
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce confusion, and make their semantics rigid. Improves efficiency of resched_task and some cpu_idle routines. * In resched_task: - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held, and as we hold it during resched_task, then there is no need for an atomic test and set there. The only other time this should be set is when the task's quantum expires, in the timer interrupt - this is protected against because the rq lock is irq-safe. - If TIF_NEED_RESCHED is set, then we don't need to do anything. It won't get unset until the task get's schedule()d off. - If we are running on the same CPU as the task we resched, then set TIF_NEED_RESCHED and no further action is required. - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set after TIF_NEED_RESCHED has been set, then we need to send an IPI. Using these rules, we are able to remove the test and set operation in resched_task, and make clear the previously vague semantics of POLLING_NRFLAG. * In idle routines: - Enter cpu_idle with preempt disabled. When the need_resched() condition becomes true, explicitly call schedule(). This makes things a bit clearer (IMO), but haven't updated all architectures yet. - Many do a test and clear of TIF_NEED_RESCHED for some reason. According to the resched_task rules, this isn't needed (and actually breaks the assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock held). So remove that. Generally one less locked memory op when switching to the idle thread. - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner most polling idle loops. The above resched_task semantics allow it to be set until before the last time need_resched() is checked before going into a halt requiring interrupt wakeup. Many idle routines simply never enter such a halt, and so POLLING_NRFLAG can be always left set, completely eliminating resched IPIs when rescheduling the idle task. POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>