io_uring/io-wq: make io_wq_work flags atomic

The work flags can be set/accessed from different tasks, both the
originator of the request, and the io-wq workers. While modifications
aren't concurrent, it still makes KMSAN unhappy. There's no real
downside to just making the flag reading/manipulation use proper
atomics here.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 10 insertions, 9 deletions

diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index 7d3316fe9bfc..913c92249522 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -159,7 +159,7 @@ static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
 static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
 						  struct io_wq_work *work)
 {
-	return io_get_acct(wq, !(work->flags & IO_WQ_WORK_UNBOUND));
+	return io_get_acct(wq, !(atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND));
 }
 
 static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
@@ -451,7 +451,7 @@ static void __io_worker_idle(struct io_wq *wq, struct io_worker *worker)
 
 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
 {
-	return work->flags >> IO_WQ_HASH_SHIFT;
+	return atomic_read(&work->flags) >> IO_WQ_HASH_SHIFT;
 }
 
 static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
@@ -592,8 +592,9 @@ static void io_worker_handle_work(struct io_wq_acct *acct,
 
 			next_hashed = wq_next_work(work);
 
-			if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
-				work->flags |= IO_WQ_WORK_CANCEL;
+			if (do_kill &&
+			    (atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND))
+				atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
 			wq->do_work(work);
 			io_assign_current_work(worker, NULL);
 
@@ -891,7 +892,7 @@ static bool io_wq_worker_wake(struct io_worker *worker, void *data)
 static void io_run_cancel(struct io_wq_work *work, struct io_wq *wq)
 {
 	do {
-		work->flags |= IO_WQ_WORK_CANCEL;
+		atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
 		wq->do_work(work);
 		work = wq->free_work(work);
 	} while (work);
@@ -926,7 +927,7 @@ static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
 {
 	struct io_wq_acct *acct = io_work_get_acct(wq, work);
-	unsigned long work_flags = work->flags;
+	unsigned int work_flags = atomic_read(&work->flags);
 	struct io_cb_cancel_data match = {
 		.fn		= io_wq_work_match_item,
 		.data		= work,
@@ -939,7 +940,7 @@ void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
 	 * been marked as one that should not get executed, cancel it here.
 	 */
 	if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
-	    (work->flags & IO_WQ_WORK_CANCEL)) {
+	    (work_flags & IO_WQ_WORK_CANCEL)) {
 		io_run_cancel(work, wq);
 		return;
 	}
@@ -982,7 +983,7 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
 	unsigned int bit;
 
 	bit = hash_ptr(val, IO_WQ_HASH_ORDER);
-	work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
+	atomic_or(IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT), &work->flags);
 }
 
 static bool __io_wq_worker_cancel(struct io_worker *worker,
@@ -990,7 +991,7 @@ static bool __io_wq_worker_cancel(struct io_worker *worker,
 				  struct io_wq_work *work)
 {
 	if (work && match->fn(work, match->data)) {
-		work->flags |= IO_WQ_WORK_CANCEL;
+		atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
 		__set_notify_signal(worker->task);
 		return true;
 	}