[PATCH AUTOSEL 4.19 08/10] 9p: trans_fd/p9_conn_cancel: drop client lock earlier

[Sasha Levin]

From: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>

[ Upstream commit 52f1c45dde9136f964d63a77d19826c8a74e2c7f ]

syzbot reported a double-lock here and we no longer need this
lock after requests have been moved off to local list:
just drop the lock earlier.

Link: https://lkml.kernel.org/r/20220904064028.1305220-1-asmadeus@xxxxxxxxxxxxx
Reported-by: syzbot+50f7e8d06c3768dd97f3@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
Tested-by: Schspa Shi <schspa@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/9p/trans_fd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 9268f808afc0..7d68b4a63997 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -220,6 +220,8 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
 		list_move(&req->req_list, &cancel_list);
 	}
 
+	spin_unlock(&m->client->lock);
+
 	list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
 		p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req);
 		list_del(&req->req_list);
@@ -227,7 +229,6 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
 			req->t_err = err;
 		p9_client_cb(m->client, req, REQ_STATUS_ERROR);
 	}
-	spin_unlock(&m->client->lock);
 }
 
 static __poll_t
-- 
2.35.1