diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2025-08-19 18:10:13 +0200 |
|---|---|---|
| committer | Dominique Martinet <asmadeus@codewreck.org> | 2025-09-19 16:34:51 +0900 |
| commit | e8fe3f07a357c39d429e02ca34f740692d88967a (patch) | |
| tree | d447f2f17577e67bb08b0b2f869feb1c7bd2136a | |
| parent | 674b56aa57f9379854cb6798c3bbcef7e7b51ab7 (diff) | |
9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN
p9_read_work() doesn't set Rworksched and doesn't do schedule_work(m->rq)
if list_empty(&m->req_list).
However, if the pipe is full, we need to read more data and this used to
work prior to commit aaec5a95d59615 ("pipe_read: don't wake up the writer
if the pipe is still full").
p9_read_work() does p9_fd_read() -> ... -> anon_pipe_read() which (before
the commit above) triggered the unnecessary wakeup. This wakeup calls
p9_pollwake() which kicks p9_poll_workfn() -> p9_poll_mux(), p9_poll_mux()
will notice EPOLLIN and schedule_work(&m->rq).
This no longer happens after the optimization above, change p9_fd_request()
to use p9_poll_mux() instead of only checking for EPOLLOUT.
Reported-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Tested-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68a2de8f.050a0220.e29e5.0097.GAE@google.com/
Link: https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@google.com/
Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Message-ID: <20250819161013.GB11345@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
| -rw-r--r-- | net/9p/trans_fd.c | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 8992d8bebbdd..a516745f732f 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -666,7 +666,6 @@ static void p9_poll_mux(struct p9_conn *m) static int p9_fd_request(struct p9_client *client, struct p9_req_t *req) { - __poll_t n; int err; struct p9_trans_fd *ts = client->trans; struct p9_conn *m = &ts->conn; @@ -686,13 +685,7 @@ static int p9_fd_request(struct p9_client *client, struct p9_req_t *req) list_add_tail(&req->req_list, &m->unsent_req_list); spin_unlock(&m->req_lock); - if (test_and_clear_bit(Wpending, &m->wsched)) - n = EPOLLOUT; - else - n = p9_fd_poll(m->client, NULL, NULL); - - if (n & EPOLLOUT && !test_and_set_bit(Wworksched, &m->wsched)) - schedule_work(&m->wq); + p9_poll_mux(m); return 0; } |