6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavel Begunkov <asml.silence@xxxxxxxxx> commit 8d09a88ef9d3cb7d21d45c39b7b7c31298d23998 upstream. Conditional locking is never great, in case of __io_cqring_overflow_flush(), which is a slow path, it's not justified. Don't handle IOPOLL separately, always grab uring_lock for overflow flushing. Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> Link: https://lore.kernel.org/r/162947df299aa12693ac4b305dacedab32ec7976.1712708261.git.asml.silence@xxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- io_uring/io_uring.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -667,6 +667,8 @@ static void io_cqring_overflow_kill(stru struct io_overflow_cqe *ocqe; LIST_HEAD(list); + lockdep_assert_held(&ctx->uring_lock); + spin_lock(&ctx->completion_lock); list_splice_init(&ctx->cq_overflow_list, &list); clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq); @@ -683,6 +685,8 @@ static void __io_cqring_overflow_flush(s { size_t cqe_size = sizeof(struct io_uring_cqe); + lockdep_assert_held(&ctx->uring_lock); + if (__io_cqring_events(ctx) == ctx->cq_entries) return; @@ -727,12 +731,9 @@ static void __io_cqring_overflow_flush(s static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx) { - /* iopoll syncs against uring_lock, not completion_lock */ - if (ctx->flags & IORING_SETUP_IOPOLL) - mutex_lock(&ctx->uring_lock); + mutex_lock(&ctx->uring_lock); __io_cqring_overflow_flush(ctx); - if (ctx->flags & IORING_SETUP_IOPOLL) - mutex_unlock(&ctx->uring_lock); + mutex_unlock(&ctx->uring_lock); } static void io_cqring_overflow_flush(struct io_ring_ctx *ctx) @@ -1611,6 +1612,8 @@ static int io_iopoll_check(struct io_rin unsigned int nr_events = 0; unsigned long check_cq; + lockdep_assert_held(&ctx->uring_lock); + if (!io_allowed_run_tw(ctx)) return -EEXIST;
