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 --- kernel/stop_machine.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 738b411ff2d3..a473bd0cb71b 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -22,9 +22,17 @@ enum stopmachine_state { STOPMACHINE_WAIT, STOPMACHINE_PREPARE, STOPMACHINE_DISABLE_IRQ, + STOPMACHINE_RUN, STOPMACHINE_EXIT, }; +struct stop_machine_data { + int (*fn)(void *); + void *data; + struct completion done; + int run_all; +} smdata; + static enum stopmachine_state stopmachine_state; static unsigned int stopmachine_num_threads; static atomic_t stopmachine_thread_ack; @@ -33,6 +41,7 @@ static int stopmachine(void *cpu) { int irqs_disabled = 0; int prepared = 0; + int ran = 0; cpumask_of_cpu_ptr(cpumask, (int)(long)cpu); set_cpus_allowed_ptr(current, cpumask); @@ -58,6 +67,11 @@ static int stopmachine(void *cpu) prepared = 1; smp_mb(); /* Must read state first. */ atomic_inc(&stopmachine_thread_ack); + } else if (stopmachine_state == STOPMACHINE_RUN && !ran) { + smdata.fn(smdata.data); + ran = 1; + smp_mb(); /* Must read state first. */ + atomic_inc(&stopmachine_thread_ack); } /* Yield in first stage: migration threads need to * help our sisters onto their CPUs. */ @@ -136,11 +150,10 @@ static void restart_machine(void) preempt_enable_no_resched(); } -struct stop_machine_data { - int (*fn)(void *); - void *data; - struct completion done; -}; +static void run_other_cpus(void) +{ + stopmachine_set_state(STOPMACHINE_RUN); +} static int do_stop(void *_smdata) { @@ -150,6 +163,8 @@ static int do_stop(void *_smdata) ret = stop_machine(); if (ret == 0) { ret = smdata->fn(smdata->data); + if (smdata->run_all) + run_other_cpus(); restart_machine(); } @@ -173,14 +188,17 @@ struct task_struct *__stop_machine_run(int (*fn)(void *), void *data, struct stop_machine_data smdata; struct task_struct *p; + mutex_lock(&stopmachine_mutex); + smdata.fn = fn; smdata.data = data; + smdata.run_all = (cpu == ALL_CPUS) ? 1 : 0; init_completion(&smdata.done); - mutex_lock(&stopmachine_mutex); + smp_wmb(); /* make sure other cpus see smdata updates */ /* If they don't care which CPU fn runs on, bind to any online one. */ - if (cpu == NR_CPUS) + if (cpu == NR_CPUS || cpu == ALL_CPUS) cpu = raw_smp_processor_id(); p = kthread_create(do_stop, &smdata, "kstopmachine"); -- cgit v1.2.3-59-g8ed1b