[PATCH v6 21/46] block: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-02-18 12:43:30
Also in:
linux-arch, linux-pm, linuxppc-dev, lkml, netdev
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Srivatsa S. Bhat <redacted> --- block/blk-softirq.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 467c8de..448f9a9 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c@@ -58,6 +58,8 @@ static void trigger_softirq(void *data) */ static int raise_blk_irq(int cpu, struct request *rq) { + get_online_cpus_atomic(); + if (cpu_online(cpu)) { struct call_single_data *data = &rq->csd;
@@ -66,9 +68,11 @@ static int raise_blk_irq(int cpu, struct request *rq) data->flags = 0; __smp_call_function_single(cpu, data, 0); + put_online_cpus_atomic(); return 0; } + put_online_cpus_atomic(); return 1; } #else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */