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| author | Jens Axboe <axboe@kernel.dk> | 2025-01-08 18:28:05 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-01-09 15:16:45 +0100 |
| commit | c9a40292a44e78f71258b8522655bffaf5753bdb (patch) | |
| tree | de3ee6a1d24d45a6f5ea1cac57210014992c9efc /io_uring | |
| parent | io_uring: silence false positive warnings (diff) | |
| download | linux-c9a40292a44e78f71258b8522655bffaf5753bdb.tar.xz linux-c9a40292a44e78f71258b8522655bffaf5753bdb.zip | |
io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
io_eventfd_do_signal() is invoked from an RCU callback, but when
dropping the reference to the io_ev_fd, it calls io_eventfd_free()
directly if the refcount drops to zero. This isn't correct, as any
potential freeing of the io_ev_fd should be deferred another RCU grace
period.
Just call io_eventfd_put() rather than open-code the dec-and-test and
free, which will correctly defer it another RCU grace period.
Fixes: 21a091b970cd ("io_uring: signal registered eventfd to process deferred task work")
Reported-by: Jann Horn <jannh@google.com>
Cc: stable@vger.kernel.org
Tested-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Li Zetao<lizetao1@huawei.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/eventfd.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/io_uring/eventfd.c b/io_uring/eventfd.c index fab936d31ba8..100d5da94cb9 100644 --- a/io_uring/eventfd.c +++ b/io_uring/eventfd.c @@ -33,20 +33,18 @@ static void io_eventfd_free(struct rcu_head *rcu) kfree(ev_fd); } -static void io_eventfd_do_signal(struct rcu_head *rcu) +static void io_eventfd_put(struct io_ev_fd *ev_fd) { - struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); - - eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); - if (refcount_dec_and_test(&ev_fd->refs)) - io_eventfd_free(rcu); + call_rcu(&ev_fd->rcu, io_eventfd_free); } -static void io_eventfd_put(struct io_ev_fd *ev_fd) +static void io_eventfd_do_signal(struct rcu_head *rcu) { - if (refcount_dec_and_test(&ev_fd->refs)) - call_rcu(&ev_fd->rcu, io_eventfd_free); + struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); + + eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); + io_eventfd_put(ev_fd); } static void io_eventfd_release(struct io_ev_fd *ev_fd, bool put_ref) |