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* [ARM] 3271/1: ARM EABI: fix calling of cmpxchg syscall emulationNicolas Pitre2006-01-181-1/+4
| | | | | | | | | | | Patch from Nicolas Pitre This is kernel provided user space code. Since a syscall is used, it has to be updated to work with EABI. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] 3270/1: ARM EABI: fix sigreturn and rt_sigreturnNicolas Pitre2006-01-182-12/+19
| | | | | | | | | | | | Patch from Nicolas Pitre The signal return path consists of user code provided by the kernel. Since a syscall is used, it has to be updated to work with EABI. Noticed by Daniel Jacobowitz. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds2006-01-1412-61/+574
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| * [ARM] 3262/4: allow ptraced syscalls to be overridenNicolas Pitre2006-01-142-3/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre This is needed by strace to properly handle the tracing of some system calls. It could be useful for other applications as well. Based on an earlier patch from Daniel Jacobowitz. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Daniel Jacobowitz <dan@debian.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3110/5: old ABI compat: multi-ABI syscall entry supportNicolas Pitre2006-01-143-35/+100
| | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre This patch adds the required code to support both user space ABIs at the same time. A second syscall table is created to include legacy ABI syscalls that need an ABI compat wrapper. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3109/1: old ABI compat: syscall wrappers for ABI impedance matchingNicolas Pitre2006-01-143-0/+372
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre The difference between EABI and the legacy ABI may affect either structure member alignment and/or argument register selection. The patch has the details. Included are wrappers for the following syscalls: sys_stat64 sys_lstat64 sys_fstat64 sys_fcntl64 sys_epoll_ctl sys_epoll_wait sys_ipc sys_semop sys_semtimedop sys_pread64 sys_pwrite64 sys_truncate64 sys_ftruncate64 sys_readahead Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3108/2: old ABI compat: statfs64 and fstatfs64Nicolas Pitre2006-01-142-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre struct statfs64 has extra padding with EABI growing its size from 84 to 88. This struct is now __attribute__((packed,aligned(4))) with a small assembly wrapper to force the sz argument to 84 if it is 88 to avoid copying the extra padding over user space memory unexpecting it. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3105/4: ARM EABI: new syscall entry conventionNicolas Pitre2006-01-142-15/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre For a while we wanted to change the way syscalls were called on ARM. Instead of encoding the syscall number in the swi instruction which requires reading back the instruction from memory to extract that number and polluting the data cache, it was decided that simply storing the syscall number into r7 would be more efficient. Since this represents an ABI change then making that change at the same time as EABI support is the right thing to do. It is now expected that EABI user space binaries put the syscall number into r7 and use "swi 0" to call the kernel. Syscall register argument are also expected to have "EABI arrangement" i.e. 64-bit arguments should be put in a pair of registers from an even register number. Example with long ftruncate64(unsigned int fd, loff_t length): legacy ABI: - put fd into r0 - put length into r1-r2 - use "swi #(0x900000 + 194)" to call the kernel new ARM EABI: - put fd into r0 - put length into r2-r3 (skipping over r1) - put 194 into r7 - use "swi 0" to call the kernel Note that it is important to use 0 for the swi argument as backward compatibility with legacy ABI user space relies on this. The syscall macros in asm-arm/unistd.h were also updated to support both ABIs and implement the right call method automatically. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3104/1: ARM EABI: new helper function namesNicolas Pitre2006-01-141-0/+22
| | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre The ARM EABI defines new names for GCC helper functions. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3103/1: ARM EABI: stack pointer must be 64-bit aligned (part 2)Nicolas Pitre2006-01-141-8/+9
| | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre We must make sure that assembly code that modifies the stack pointer before calling a C function does it so it remains 64-bit aligned. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3102/1: ARM EABI: stack pointer must be 64-bit aligned after a CPU ↵Nicolas Pitre2006-01-142-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | exception Patch from Nicolas Pitre The ARM EABI says that the stack pointer has to be 64-bit aligned for reasons already mentioned in patch #3101 when calling C functions. We therefore must verify and adjust sp accordingly when taking an exception from kernel mode since sp might not necessarily be 64-bit aligned if the exception occurs in the middle of a kernel function. If the exception occurs while in user mode then no sp fixup is needed as long as sizeof(struct pt_regs) as well as any additional syscall data stack space remain multiples of 8. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] Support register switch in nommu modeHyok S. Choi2006-01-131-0/+7
| | | | | | | | | | | | | | This patch adds register switch support in nommu mode. Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3259/1: remove phys_ram from struct machine_desc (part 1)Nicolas Pitre2006-01-131-4/+3
| | | | | | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre This field is redundent since it must be equal to PHYS_OFFSET anyway. First, let's use PHYS_OFFSET directly instead. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* | [PATCH] Add ecard_bus_type probe/remove/shutdown methodsRussell King2006-01-131-6/+8
|/ | | | | Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds2006-01-123-11/+15
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| * [ARM] Convert some arm semaphores to mutexesArjan van de Ven2006-01-121-3/+4
| | | | | | | | | | | | | | | | The arm clock semaphores are strict mutexes, convert them to the new mutex implementation Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3256/1: Make the function-returning ldm's use sp as the base registerCatalin Marinas2006-01-121-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch from Catalin Marinas If the low interrupt latency mode is enabled for the CPU (from ARMv6 onwards), the ldm/stm instructions are no longer atomic. An ldm instruction restoring the sp and pc registers can be interrupted immediately after sp was updated but before the pc. If this happens, the CPU restores the base register to the value before the ldm instruction but if the base register is not sp, the interrupt routine will corrupt the stack and the restarted ldm instruction will load garbage. Note that future ARM cores might always run in the low interrupt latency mode. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| * [ARM] 3234/1: Update cpu_architecture() to deal with the new ID formatCatalin Marinas2006-01-121-6/+9
| | | | | | | | | | | | | | | | | | | | Patch from Catalin Marinas Since ARM1176, the CPU ID format has changed and it will also be used for future ARM architectures. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* | [PATCH] arm: task_stack_page()Al Viro2006-01-123-4/+4
| | | | | | | | | | | | 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>
* | [PATCH] arm: end_of_stack()Al Viro2006-01-122-2/+2
| | | | | | | | | | | | 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>
* | [PATCH] arm: task_pt_regs()Al Viro2006-01-122-25/+7
| | | | | | | | | | | | 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>
* | [PATCH] arm: task_thread_info()Al Viro2006-01-122-7/+7
| | | | | | | | | | | | 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>
* | [PATCH] capable/capability.h (arch/)Randy Dunlap2006-01-111-0/+1
|/ | | | | | | | 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>
* [ARM] Only call set_type method in setup_irq if it's definedRussell King2006-01-091-1/+2
| | | | Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [PATCH] remove gcc-2 checksAndrew Morton2006-01-081-7/+2
| | | | | | | | | | | | | Remove various things which were checking for gcc-1.x and gcc-2.x compilers. From: Adrian Bunk <bunk@stusta.de> Some documentation updates and removes some code paths for gcc < 3.2. Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] IRQ type flagsRussell King2006-01-081-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some ARM platforms have the ability to program the interrupt controller to detect various interrupt edges and/or levels. For some platforms, this is critical to setup correctly, particularly those which the setting is dependent on the device. Currently, ARM drivers do (eg) the following: err = request_irq(irq, ...); set_irq_type(irq, IRQT_RISING); However, if the interrupt has previously been programmed to be level sensitive (for whatever reason) then this will cause an interrupt storm. Hence, if we combine set_irq_type() with request_irq(), we can then safely set the type prior to unmasking the interrupt. The unfortunate problem is that in order to support this, these flags need to be visible outside of the ARM architecture - drivers such as smc91x need these flags and they're cross-architecture. Finally, the SA_TRIGGER_* flag passed to request_irq() should reflect the property that the device would like. The IRQ controller code should do its best to select the most appropriate supported mode. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [ARM] 3229/1: Remove uneeded ARM apm dependency on PM_LEGACYRichard Purdie2006-01-051-12/+7
| | | | | | | | | | Patch from Richard Purdie ARM doesn't use ACPI so ARM's apm implementation has no need to depend on PM_LEGACY. This patch removes that dependency. Signed-off-by: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Move DMA exports to be next to each functionRussell King2006-01-041-14/+12
| | | | Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Remove definition of MAX_DMA_CHANNELS to zeroRussell King2006-01-041-28/+0
| | | | | | | | | Since we now only build arch/arm/kernel/dma.c on machine types which set ISA_DMA_API, we don't need to define MAX_DMA_CHANNELS to 0 to indicate this - this definition becomes superfluous. Remove it. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Refine selection of ISA_DMA_API and generic dma.c codeRussell King2006-01-041-1/+2
| | | | | | | | | | | | ISA_DMA_API tells the rest of the kernel if the ISA DMA API is available. Select this symbol only on machine types which make use of the ISA DMA API. Make building of arch/arm/kernel/dma.c depend on this symbol - if a machine does not support the ISA DMA API, it's pointless building this file. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Use core_initcall() to initialise ARM DMARussell King2006-01-042-4/+4
| | | | | | | There's no need to have DMA initialised at the same time as interrupts. Move it to a core_initcall(). Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Remove '__address' from scatterlist and convert to DMA APIRussell King2006-01-042-18/+17
| | | | | | | | | | | | The old __address element in struct scatterlist remained from older kernels because the ARM DMA emulation code made use of it. Move this field into struct dma_struct, and convert DMA emulation code to setup a SG entry as required. Also, convert DMA emulation code to use the new DMA API rather than the PCI DMA API. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Move ISA DMA bus_to_virt() out of set_dma_addr()Russell King2006-01-041-4/+4
| | | | | | | Allow the compiler to optimise the bus_to_virt(virt_to_bus()) transformation in the ARM ISA DMA interface. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Cleanup ARM includesRussell King2006-01-036-12/+1
| | | | | | | | | | | | | | | | arch/arm/kernel/entry-armv.S has contained a comment suggesting that asm/hardware.h and asm/arch/irqs.h should be moved into the asm/arch/entry-macro.S include. So move the includes to these two files as required. Add missing includes (asm/hardware.h, asm/io.h) to asm/arch/system.h includes which use those facilities, and remove asm/io.h from kernel/process.c. Remove other unnecessary includes from arch/arm/kernel, arch/arm/mm and arch/arm/mach-footbridge. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Make kernel link address depend on PAGE_OFFSETRussell King2006-01-033-8/+8
| | | | | | | | | | | | We are coding the kernel link address into the makefiles, which is invisibly dependent on PAGE_OFFSET. If PAGE_OFFSET is changed, the makefiles also need to be changed. Make adjustments such that the makefiles encode just the offset from PAGE_OFFSET for the kernel link address, and use PAGE_OFFSET in the linker scripts directly. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] 3210/1: add missing memory barrier helper for NPTL supportNicolas Pitre2005-12-191-0/+49
| | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre Strictly speaking, the NPTL kernel helpers are required for pre ARMv6 only. They are available on ARMv6+ as well for obvious compatibility reasons. However there are cases where extra memory barriers are needed when using an SMP ARMv6 machine but not on pre-ARMv6. This patch adds a memory barrier kernel helper that glibc can use as needed for pre-ARMv6 binaries to be forward compatible with an SMP kernel on ARMv6, as well as the necessary dmb instructions to the cmpxchg helper. Signed-off-by: Nicolas Pitre <nico@cam.org> Acked-by: Daniel Jacobowitz <dan@codesourcery.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Fix sys_sendto and sys_recvfrom 6-arg syscallsRussell King2005-12-172-22/+6
| | | | | | | | | | | | | | Rather than providing more wrappers for 6-arg syscalls, arrange for them to be supported as standard. This just means that we always store the 6th argument on the stack, rather than in the wrappers. This means we eliminate the wrappers for: * sys_futex * sys_arm_fadvise64_64 * sys_mbind * sys_ipc Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] 3205/1: Handle new EABI relocations when loading kernel modules.Daniel Jacobowitz2005-12-141-0/+2
| | | | | | | | | | | Patch from Daniel Jacobowitz Handle new EABI relocations when loading kernel modules. This is necessary for CONFIG_AEABI kernels, and also for some broken (since fixed) old ABI toolchains. Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] 3200/1: Singlestep over ARM BX and BLX instructions using ptrace fixNikola Valerjev2005-12-101-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch from Nikola Valerjev Single stepping an application using ptrace() fails over ARM instructions BX and BLX. Steps to reproduce: Compile and link the following files main.c ----- void foo(); int main() { foo(); return 0; } foo.s ----- .text .globl foo foo: BX LR Using ptrace() functionality, run to main(), and start singlestepping. Singlestep over \"BX LR\" instruction won\'t transfer the control back to main, but run the code to completion. This problems seems to be in the function get_branch_address() in arch/arm/kernel/ptrace.c. The function doesn\'t seem to recognize BX and BLX instructions as branches. BX and BLX instructions can be used to convert from ARM to Thumb mode if the target address has the low bit set. However, they are also perfectly legal in the ARM only mode. Although other things in the kernel seem to indicate that only ARM mode is accepted (and not Thumb), many compilers will generate BX and BLX instructions even when generating ARM only code. Signed-off-by: Nikola Valerjev <nikola@ghs.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Remove mach-types.h from head.SRussell King2005-11-251-8/+3
| | | | | | | | We don't really need to check whether the machine type is Netwinder or CATS before setting up the PCI IO mapping for debugging. This allows us to eliminate asm/mach-types.h from head.S Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] 3168/1: Update ARM signal delivery and maskingDaniel Jacobowitz2005-11-192-15/+13
| | | | | | | | | | | | | | | | | Patch from Daniel Jacobowitz After delivering a signal (creating its stack frame) we must check for additional pending unblocked signals before returning to userspace. Otherwise signals may be delayed past the next syscall or reschedule. Once that was fixed it became obvious that the ARM signal mask manipulation was broken. It was a little bit broken before the recent SA_NODEFER changes, and then very broken after them. We must block the requested signals before starting the handler or the same signal can be delivered again before the handler even gets a chance to run. Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Fix get_user when passed a const pointerRussell King2005-11-181-1/+0
| | | | | | | | Unfortunately, later gcc versions error out when our get_user is passed a const pointer, since we write to a temporary variable declared as typeof(*(p)) which propagates the const-ness. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [ARM] Improve comment about ASSERT()s in vmlinux.lds.SRussell King2005-11-171-1/+5
| | | | | | | Provide folk with an idea what to do if the ASSERT statements fail with their linker. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds2005-11-131-3/+1
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| * [ARM] Restore apparant pointless change in arch/arm/kernel/smp.cRussell King2005-11-121-3/+1
| | | | | | | | | | | | Restore smp.c back to how it used to be. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* | [PATCH] move pm_register/etc. to CONFIG_PM_LEGACY, pm_legacy.hJeff Garzik2005-11-131-0/+1
|/ | | | | | | | Since few people need the support anymore, this moves the legacy pm_xxx functions to CONFIG_PM_LEGACY, and include/linux/pm_legacy.h. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds2005-11-091-1/+1
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| * [ARM] 3100/1: simplify a pointer computationNicolas Pitre2005-11-091-1/+1
| | | | | | | | | | | | | | | | | | Patch from Nicolas Pitre Looks clearer this way. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* | [PATCH] sched: resched and cpu_idle reworkNick Piggin2005-11-091-5/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | [PATCH] sched: disable preempt in idle tasksNick Piggin2005-11-092-3/+6
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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