Commit 2f3cc8e4 authored by Olivier Langlois's avatar Olivier Langlois Committed by Jens Axboe
Browse files

io_uring/napi: protect concurrent io_napi_entry timeout accesses 



io_napi_entry timeout value can be updated while accessed from the poll
functions.

Its concurrent accesses are wrapped with READ_ONCE()/WRITE_ONCE() macros
to avoid incorrect compiler optimizations.

Signed-off-by: default avatarOlivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/3de3087563cf98f75266fd9f85fdba063a8720db.1728828877.git.olivier@trillion01.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 48324271

io_uring/napi.c

+3 −3
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ void __io_napi_add(struct io_ring_ctx *ctx, struct socket *sock) 
	rcu_read_lock();

	e = io_napi_hash_find(hash_list, napi_id);

	if (e) {

		e->timeout = jiffies + NAPI_TIMEOUT;

		WRITE_ONCE(e->timeout, jiffies + NAPI_TIMEOUT);

		rcu_read_unlock();

		return;

	}
@@ -92,7 +92,7 @@ static void __io_napi_remove_stale(struct io_ring_ctx *ctx) 


	spin_lock(&ctx->napi_lock);

	hash_for_each(ctx->napi_ht, i, e, node) {

		if (time_after(jiffies, e->timeout)) {

		if (time_after(jiffies, READ_ONCE(e->timeout))) {

			list_del(&e->list);

			hash_del_rcu(&e->node);

			kfree_rcu(e, rcu);
@@ -150,7 +150,7 @@ static bool __io_napi_do_busy_loop(struct io_ring_ctx *ctx, 
		napi_busy_loop_rcu(e->napi_id, loop_end, loop_end_arg,

				   ctx->napi_prefer_busy_poll, BUSY_POLL_BUDGET);



		if (time_after(jiffies, e->timeout))

		if (time_after(jiffies, READ_ONCE(e->timeout)))

			is_stale = true;

	}