af_unix: use freezable blocking calls in read

Avoid waking up every thread sleeping in read call on an AF_UNIX
socket during suspend and resume by calling a freezable blocking
call.  Previous patches modified the freezer to avoid sending
wakeups to threads that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 826e09938bff4203def6e5af33db49c4360f3019..c4ce243824bb19c6e600dd98da2d8a6d16747dc1 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -114,6 +114,7 @@
 #include <linux/mount.h>
 #include <net/checksum.h>
 #include <linux/security.h>
+#include <linux/freezer.h>
 
 struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
 EXPORT_SYMBOL_GPL(unix_socket_table);
@@ -1879,7 +1880,7 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
 
                set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
                unix_state_unlock(sk);
-               timeo = schedule_timeout(timeo);
+               timeo = freezable_schedule_timeout(timeo);
                unix_state_lock(sk);
                clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        }