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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH] percpu_ref: don't refer to ref->data if it isn't allocated
Date: Fri,  9 Oct 2020 12:03:56 +0800	[thread overview]
Message-ID: <20201009040356.43802-1-ming.lei@redhat.com> (raw)

We can't check ref->data->confirm_switch directly in __percpu_ref_exit(), since
ref->data may not be allocated in one not-initialized refcount.

Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 lib/percpu-refcount.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index b6350d13538a..e59eda07305e 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -109,7 +109,7 @@ static void __percpu_ref_exit(struct percpu_ref *ref)
 
 	if (percpu_count) {
 		/* non-NULL confirm_switch indicates switching in progress */
-		WARN_ON_ONCE(ref->data->confirm_switch);
+		WARN_ON_ONCE(ref->data && ref->data->confirm_switch);
 		free_percpu(percpu_count);
 		ref->percpu_count_ptr = __PERCPU_REF_ATOMIC_DEAD;
 	}
-- 
2.25.2


             reply	other threads:[~2020-10-09  4:04 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09  4:03 Ming Lei [this message]
2020-10-09  4:35 ` [PATCH] percpu_ref: don't refer to ref->data if it isn't allocated Eric Biggers
2020-10-09 18:32 ` Jens Axboe

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