From: Bob Peterson <rpeterso@redhat.com>
Date: Mon, 10 Oct 2016 13:19:52 +0000 (-0400)
Subject: dlm: remove lock_sock to avoid scheduling while atomic
X-Git-Tag: v4.14-rc1~1903^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d2fee58a3bb15b2b8f1eaff14aa3432cf0f35d8c;p=platform%2Fkernel%2Flinux-rpi.git

dlm: remove lock_sock to avoid scheduling while atomic

Before this patch, functions save_callbacks and restore_callbacks
called function lock_sock and release_sock to prevent other processes
from messing with the struct sock while the callbacks were saved and
restored. However, function add_sock calls write_lock_bh prior to
calling it save_callbacks, which disables preempts. So the call to
lock_sock would try to schedule when we can't schedule.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
---

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 485494e..df680a2 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -519,24 +519,20 @@ out:
 /* Note: sk_callback_lock must be locked before calling this function. */
 static void save_callbacks(struct connection *con, struct sock *sk)
 {
-	lock_sock(sk);
 	con->orig_data_ready = sk->sk_data_ready;
 	con->orig_state_change = sk->sk_state_change;
 	con->orig_write_space = sk->sk_write_space;
 	con->orig_error_report = sk->sk_error_report;
-	release_sock(sk);
 }
 
 static void restore_callbacks(struct connection *con, struct sock *sk)
 {
 	write_lock_bh(&sk->sk_callback_lock);
-	lock_sock(sk);
 	sk->sk_user_data = NULL;
 	sk->sk_data_ready = con->orig_data_ready;
 	sk->sk_state_change = con->orig_state_change;
 	sk->sk_write_space = con->orig_write_space;
 	sk->sk_error_report = con->orig_error_report;
-	release_sock(sk);
 	write_unlock_bh(&sk->sk_callback_lock);
 }