From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit cda286f0715c82f8117e166afd42cca068876dde ]
io_uring_cancel_task_requests() doesn't imply that the ring is going away, it may continue to work well after that. The problem is that it sets ->cq_overflow_flushed effectively disabling the CQ overflow feature
Split setting cq_overflow_flushed from flush, and do the first one only on exit. It's ok in terms of cancellations because there is a io_uring->in_idle check in __io_cqring_fill_event().
It also fixes a race with setting ->cq_overflow_flushed in io_uring_cancel_task_requests, whuch's is not atomic and a part of a bitmask with other flags. Though, the only other flag that's not set during init is drain_next, so it's not as bad for sane architectures.
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Fixes: 0f2122045b946 ("io_uring: don't rely on weak ->files references") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index b9d3209a5f9de..e9219841923cc 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1641,10 +1641,6 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
spin_lock_irqsave(&ctx->completion_lock, flags);
- /* if force is set, the ring is going away. always drop after that */ - if (force) - ctx->cq_overflow_flushed = 1; - cqe = NULL; list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) { if (tsk && req->task != tsk) @@ -8378,6 +8374,8 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) { mutex_lock(&ctx->uring_lock); percpu_ref_kill(&ctx->refs); + /* if force is set, the ring is going away. always drop after that */ + ctx->cq_overflow_flushed = 1; if (ctx->rings) io_cqring_overflow_flush(ctx, true, NULL, NULL); mutex_unlock(&ctx->uring_lock);