6.6-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Begunkov asml.silence@gmail.com
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@gmail.com Link: https://lore.kernel.org/r/162947df299aa12693ac4b305dacedab32ec7976.171270826... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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;