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@xxxxxxxxx>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
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 */
--
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