From 5c2aed622571ac7c3c6ec182d6d3c318e4b45c8b Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Thu, 28 Feb 2008 11:33:03 -0500 Subject: stop_machine: add ALL_CPUS option -allow stop_mahcine_run() to call a function on all cpus. Calling stop_machine_run() with a 'ALL_CPUS' invokes this new behavior. stop_machine_run() proceeds as normal until the calling cpu has invoked 'fn'. Then, we tell all the other cpus to call 'fn'. Signed-off-by: Jason Baron Signed-off-by: Mathieu Desnoyers Signed-off-by: Rusty Russell CC: Adrian Bunk CC: Andi Kleen CC: Alexey Dobriyan CC: Christoph Hellwig CC: mingo@elte.hu CC: akpm@osdl.org --- include/linux/stop_machine.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 5bfc553bdb2..18af011c13a 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -8,11 +8,17 @@ #include #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) + +#define ALL_CPUS ~0U + /** * stop_machine_run: freeze the machine on all CPUs and run this function * @fn: the function to run * @data: the data ptr for the @fn() - * @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS. + * @cpu: if @cpu == n, run @fn() on cpu n + * if @cpu == NR_CPUS, run @fn() on any cpu + * if @cpu == ALL_CPUS, run @fn() first on the calling cpu, and then + * concurrently on all the other cpus * * Description: This causes a thread to be scheduled on every other cpu, * each of which disables interrupts, and finally interrupts are disabled -- cgit v1.2.3 From ffdb5976c47609c862917d4c186ecbb5706d2dda Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 28 Jul 2008 12:16:28 -0500 Subject: Simplify stop_machine stop_machine creates a kthread which creates kernel threads. We can create those threads directly and simplify things a little. Some care must be taken with CPU hotunplug, which has special needs, but that code seems more robust than it was in the past. Signed-off-by: Rusty Russell Acked-by: Christian Borntraeger --- include/linux/stop_machine.h | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) (limited to 'include') diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 18af011c13a..36c2c7284eb 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -17,13 +17,12 @@ * @data: the data ptr for the @fn() * @cpu: if @cpu == n, run @fn() on cpu n * if @cpu == NR_CPUS, run @fn() on any cpu - * if @cpu == ALL_CPUS, run @fn() first on the calling cpu, and then - * concurrently on all the other cpus + * if @cpu == ALL_CPUS, run @fn() on every online CPU. * - * Description: This causes a thread to be scheduled on every other cpu, - * each of which disables interrupts, and finally interrupts are disabled - * on the current CPU. The result is that noone is holding a spinlock - * or inside any other preempt-disabled region when @fn() runs. + * Description: This causes a thread to be scheduled on every cpu, + * each of which disables interrupts. The result is that noone is + * holding a spinlock or inside any other preempt-disabled region when + * @fn() runs. * * This can be thought of as a very heavy write lock, equivalent to * grabbing every spinlock in the kernel. */ @@ -35,13 +34,10 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu); * @data: the data ptr for the @fn * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS. * - * Description: This is a special version of the above, which returns the - * thread which has run @fn(): kthread_stop will return the return value - * of @fn(). Used by hotplug cpu. + * Description: This is a special version of the above, which assumes cpus + * won't come or go while it's being called. Used by hotplug cpu. */ -struct task_struct *__stop_machine_run(int (*fn)(void *), void *data, - unsigned int cpu); - +int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu); #else static inline int stop_machine_run(int (*fn)(void *), void *data, -- cgit v1.2.3 From eeec4fad963490821348a331cca6102ae1c4a7a3 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 28 Jul 2008 12:16:30 -0500 Subject: stop_machine(): stop_machine_run() changed to use cpu mask Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all cpus), pass a cpumask_t. Allow NULL for the common case (where we don't care which CPU the function is run on): temporary cpumask_t's are usually considered bad for stack space. This deprecates stop_machine_run, to be removed soon when all the callers are dead. Signed-off-by: Rusty Russell --- include/linux/stop_machine.h | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) (limited to 'include') diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 36c2c7284eb..f1cb0ba6d71 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -5,19 +5,19 @@ (and more). So the "read" side to such a lock is anything which diables preeempt. */ #include +#include #include #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) +/* Deprecated, but useful for transition. */ #define ALL_CPUS ~0U /** - * stop_machine_run: freeze the machine on all CPUs and run this function + * stop_machine: freeze the machine on all CPUs and run this function * @fn: the function to run * @data: the data ptr for the @fn() - * @cpu: if @cpu == n, run @fn() on cpu n - * if @cpu == NR_CPUS, run @fn() on any cpu - * if @cpu == ALL_CPUS, run @fn() on every online CPU. + * @cpus: the cpus to run the @fn() on (NULL = any online cpu) * * Description: This causes a thread to be scheduled on every cpu, * each of which disables interrupts. The result is that noone is @@ -26,22 +26,22 @@ * * This can be thought of as a very heavy write lock, equivalent to * grabbing every spinlock in the kernel. */ -int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu); +int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus); /** - * __stop_machine_run: freeze the machine on all CPUs and run this function + * __stop_machine: freeze the machine on all CPUs and run this function * @fn: the function to run * @data: the data ptr for the @fn - * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS. + * @cpus: the cpus to run the @fn() on (NULL = any online cpu) * * Description: This is a special version of the above, which assumes cpus * won't come or go while it's being called. Used by hotplug cpu. */ -int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu); +int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus); #else -static inline int stop_machine_run(int (*fn)(void *), void *data, - unsigned int cpu) +static inline int stop_machine(int (*fn)(void *), void *data, + const cpumask_t *cpus) { int ret; local_irq_disable(); @@ -50,4 +50,18 @@ static inline int stop_machine_run(int (*fn)(void *), void *data, return ret; } #endif /* CONFIG_SMP */ + +static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data, + unsigned int cpu) +{ + /* If they don't care which cpu fn runs on, just pick one. */ + if (cpu == NR_CPUS) + return stop_machine(fn, data, NULL); + else if (cpu == ~0U) + return stop_machine(fn, data, &cpu_possible_map); + else { + cpumask_t cpus = cpumask_of_cpu(cpu); + return stop_machine(fn, data, &cpus); + } +} #endif /* _LINUX_STOP_MACHINE */ -- cgit v1.2.3