From 54fdade1c3332391948ec43530c02c4794a38172 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Tue, 22 Sep 2009 16:43:39 -0700 Subject: generic-ipi: make struct call_function_data lockless This patch can remove spinlock from struct call_function_data, the reasons are below: 1: add a new interface for cpumask named cpumask_test_and_clear_cpu(), it can atomically test and clear specific cpu, we can use it instead of cpumask_test_cpu() and cpumask_clear_cpu() and no need data->lock to protect those in generic_smp_call_function_interrupt(). 2: in smp_call_function_many(), after csd_lock() return, the current's cfd_data is deleted from call_function list, so it not have race between other cpus, then cfs_data is only used in smp_call_function_many() that must disable preemption and not from a hardware interrupthandler or from a bottom half handler to call, only the correspond cpu can use it, so it not have race in current cpu, no need cfs_data->lock to protect it. 3: after 1 and 2, cfs_data->lock is only use to protect cfs_data->refs in generic_smp_call_function_interrupt(), so we can define cfs_data->refs to atomic_t, and no need cfs_data->lock any more. Signed-off-by: Xiao Guangrong Cc: Ingo Molnar Cc: Jens Axboe Cc: Nick Piggin Cc: Peter Zijlstra Acked-by: Rusty Russell [akpm@linux-foundation.org: use atomic_dec_return()] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/smp.c | 29 ++++++++--------------------- 1 file changed, 8 insertions(+), 21 deletions(-) (limited to 'kernel/smp.c') diff --git a/kernel/smp.c b/kernel/smp.c index 8e218500ab1..fd47a256a24 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -29,8 +29,7 @@ enum { struct call_function_data { struct call_single_data csd; - spinlock_t lock; - unsigned int refs; + atomic_t refs; cpumask_var_t cpumask; }; @@ -39,9 +38,7 @@ struct call_single_queue { spinlock_t lock; }; -static DEFINE_PER_CPU(struct call_function_data, cfd_data) = { - .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock), -}; +static DEFINE_PER_CPU(struct call_function_data, cfd_data); static int hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) @@ -196,25 +193,18 @@ void generic_smp_call_function_interrupt(void) list_for_each_entry_rcu(data, &call_function.queue, csd.list) { int refs; - spin_lock(&data->lock); - if (!cpumask_test_cpu(cpu, data->cpumask)) { - spin_unlock(&data->lock); + if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) continue; - } - cpumask_clear_cpu(cpu, data->cpumask); - spin_unlock(&data->lock); data->csd.func(data->csd.info); - spin_lock(&data->lock); - WARN_ON(data->refs == 0); - refs = --data->refs; + refs = atomic_dec_return(&data->refs); + WARN_ON(refs < 0); if (!refs) { spin_lock(&call_function.lock); list_del_rcu(&data->csd.list); spin_unlock(&call_function.lock); } - spin_unlock(&data->lock); if (refs) continue; @@ -419,23 +409,20 @@ void smp_call_function_many(const struct cpumask *mask, data = &__get_cpu_var(cfd_data); csd_lock(&data->csd); - spin_lock_irqsave(&data->lock, flags); data->csd.func = func; data->csd.info = info; cpumask_and(data->cpumask, mask, cpu_online_mask); cpumask_clear_cpu(this_cpu, data->cpumask); - data->refs = cpumask_weight(data->cpumask); + atomic_set(&data->refs, cpumask_weight(data->cpumask)); - spin_lock(&call_function.lock); + spin_lock_irqsave(&call_function.lock, flags); /* * Place entry at the _HEAD_ of the list, so that any cpu still * observing the entry in generic_smp_call_function_interrupt() * will not miss any other list entries: */ list_add_rcu(&data->csd.list, &call_function.queue); - spin_unlock(&call_function.lock); - - spin_unlock_irqrestore(&data->lock, flags); + spin_unlock_irqrestore(&call_function.lock, flags); /* * Make the list addition visible before sending the ipi. -- cgit v1.2.3-70-g09d2 From 0748bd01773395003208996c4c0b3f80caf80976 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 24 Sep 2009 09:34:46 -0600 Subject: cpumask: remove arch_send_call_function_ipi Now everyone is converted to arch_send_call_function_ipi_mask, remove the shim and the #defines. Signed-off-by: Rusty Russell --- arch/alpha/include/asm/smp.h | 1 - arch/arm/include/asm/smp.h | 1 - arch/ia64/include/asm/smp.h | 1 - arch/m32r/include/asm/smp.h | 1 - arch/mips/include/asm/smp.h | 1 - arch/parisc/include/asm/smp.h | 1 - arch/powerpc/include/asm/smp.h | 1 - arch/s390/include/asm/smp.h | 1 - arch/sh/include/asm/smp.h | 1 - arch/sparc/include/asm/smp_64.h | 1 - arch/x86/include/asm/smp.h | 1 - kernel/smp.c | 7 ------- 12 files changed, 18 deletions(-) (limited to 'kernel/smp.c') diff --git a/arch/alpha/include/asm/smp.h b/arch/alpha/include/asm/smp.h index 8818a1bcdc8..3f390e8cc0b 100644 --- a/arch/alpha/include/asm/smp.h +++ b/arch/alpha/include/asm/smp.h @@ -48,7 +48,6 @@ extern int smp_num_cpus; extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #else /* CONFIG_SMP */ diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index a06e735b262..e0d763be184 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -93,7 +93,6 @@ extern void platform_cpu_enable(unsigned int cpu); extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask /* * show local interrupt info diff --git a/arch/ia64/include/asm/smp.h b/arch/ia64/include/asm/smp.h index d217d1d4e05..0b3b3997dec 100644 --- a/arch/ia64/include/asm/smp.h +++ b/arch/ia64/include/asm/smp.h @@ -127,7 +127,6 @@ extern int is_multithreading_enabled(void); extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #else /* CONFIG_SMP */ diff --git a/arch/m32r/include/asm/smp.h b/arch/m32r/include/asm/smp.h index c2be49d408a..e67ded1aab9 100644 --- a/arch/m32r/include/asm/smp.h +++ b/arch/m32r/include/asm/smp.h @@ -89,7 +89,6 @@ extern unsigned long send_IPI_mask_phys(cpumask_t, int, int); extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #endif /* not __ASSEMBLY__ */ diff --git a/arch/mips/include/asm/smp.h b/arch/mips/include/asm/smp.h index 48c1967961a..e15f11a0931 100644 --- a/arch/mips/include/asm/smp.h +++ b/arch/mips/include/asm/smp.h @@ -79,6 +79,5 @@ extern asmlinkage void smp_call_function_interrupt(void); extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #endif /* __ASM_SMP_H */ diff --git a/arch/parisc/include/asm/smp.h b/arch/parisc/include/asm/smp.h index 21eb45a5262..2e73623feb6 100644 --- a/arch/parisc/include/asm/smp.h +++ b/arch/parisc/include/asm/smp.h @@ -30,7 +30,6 @@ extern void smp_send_all_nop(void); extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #endif /* !ASSEMBLY */ diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 1491bfe822d..d9ea8d39c34 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -147,7 +147,6 @@ extern struct smp_ops_t *smp_ops; extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask /* Definitions relative to the secondary CPU spin loop * and entry point. Not all of them exist on both 32 and diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h index 6de62189a48..a868b272c25 100644 --- a/arch/s390/include/asm/smp.h +++ b/arch/s390/include/asm/smp.h @@ -63,7 +63,6 @@ extern int smp_cpu_polarization[]; extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #endif diff --git a/arch/sh/include/asm/smp.h b/arch/sh/include/asm/smp.h index ca64f43abe6..53ef26ced75 100644 --- a/arch/sh/include/asm/smp.h +++ b/arch/sh/include/asm/smp.h @@ -44,7 +44,6 @@ void plat_send_ipi(unsigned int cpu, unsigned int message); void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask #else diff --git a/arch/sparc/include/asm/smp_64.h b/arch/sparc/include/asm/smp_64.h index becb6bf353a..f49e11cd4de 100644 --- a/arch/sparc/include/asm/smp_64.h +++ b/arch/sparc/include/asm/smp_64.h @@ -36,7 +36,6 @@ extern int sparc64_multi_core; extern void arch_send_call_function_single_ipi(int cpu); extern void arch_send_call_function_ipi_mask(const struct cpumask *mask); -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask /* * General functions that each host system must provide. diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 6a84ed166ae..1e796782cd7 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -121,7 +121,6 @@ static inline void arch_send_call_function_single_ipi(int cpu) smp_ops.send_call_func_single_ipi(cpu); } -#define arch_send_call_function_ipi_mask arch_send_call_function_ipi_mask static inline void arch_send_call_function_ipi_mask(const struct cpumask *mask) { smp_ops.send_call_func_ipi(mask); diff --git a/kernel/smp.c b/kernel/smp.c index fd47a256a24..c9d1c7835c2 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -347,13 +347,6 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, generic_exec_single(cpu, data, wait); } -/* Deprecated: shim for archs using old arch_send_call_function_ipi API. */ - -#ifndef arch_send_call_function_ipi_mask -# define arch_send_call_function_ipi_mask(maskp) \ - arch_send_call_function_ipi(*(maskp)) -#endif - /** * smp_call_function_many(): Run a function on a set of other CPUs. * @mask: The set of cpus to run on (only runs on online subset). -- cgit v1.2.3-70-g09d2