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| author | Jens Axboe <axboe@kernel.dk> | 2024-06-03 11:19:10 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-06-16 14:54:55 -0600 |
| commit | 60b6c075e8eb8bd23c106e2ab13370a146a94a5b (patch) | |
| tree | c0e9290454a312d572705bbb9f6d242a5ba32605 /io_uring/register.c | |
| parent | f4eaf8eda89e1ae5d8274297094687245293deff (diff) | |
| download | lwn-60b6c075e8eb8bd23c106e2ab13370a146a94a5b.tar.gz lwn-60b6c075e8eb8bd23c106e2ab13370a146a94a5b.zip | |
io_uring/eventfd: move to more idiomatic RCU free usage
In some ways, it just "happens to work" currently with using the ops
field for both the free and signaling bit. But it depends on ordering
of operations in terms of freeing and signaling. Clean it up and use the
usual refs == 0 under RCU read side lock to determine if the ev_fd is
still valid, and use the reference to gate the freeing as well.
Fixes: 21a091b970cd ("io_uring: signal registered eventfd to process deferred task work")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring/register.c')
| -rw-r--r-- | io_uring/register.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/io_uring/register.c b/io_uring/register.c index c0010a66a6f2..212711e9bc8a 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -63,9 +63,9 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg, ev_fd->eventfd_async = eventfd_async; ctx->has_evfd = true; - rcu_assign_pointer(ctx->io_ev_fd, ev_fd); atomic_set(&ev_fd->refs, 1); atomic_set(&ev_fd->ops, 0); + rcu_assign_pointer(ctx->io_ev_fd, ev_fd); return 0; } @@ -78,8 +78,8 @@ int io_eventfd_unregister(struct io_ring_ctx *ctx) if (ev_fd) { ctx->has_evfd = false; rcu_assign_pointer(ctx->io_ev_fd, NULL); - if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_FREE_BIT), &ev_fd->ops)) - call_rcu(&ev_fd->rcu, io_eventfd_ops); + if (atomic_dec_and_test(&ev_fd->refs)) + call_rcu(&ev_fd->rcu, io_eventfd_free); return 0; } |