From b2bd1cf99f3e7c8fbf12ea07af2c6998e1209e25 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 30 Jul 2020 18:43:47 +0300 Subject: [PATCH] io_uring: fix racy overflow count reporting All ->cq_overflow modifications should be under completion_lock, otherwise it can report a wrong number to the userspace. Fix it in io_uring_cancel_files(). Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 11f4ab87e08f..6e2322525da6 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7847,10 +7847,9 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx, clear_bit(0, &ctx->cq_check_overflow); ctx->rings->sq_flags &= ~IORING_SQ_CQ_OVERFLOW; } - spin_unlock_irq(&ctx->completion_lock); - WRITE_ONCE(ctx->rings->cq_overflow, atomic_inc_return(&ctx->cached_cq_overflow)); + spin_unlock_irq(&ctx->completion_lock); /* * Put inflight ref and overflow ref. If that's -- 2.11.0