path: root/net/unix
diff options
authorWANG Cong <xiyou.wangcong@gmail.com>2016-11-17 15:55:26 -0800
committerDavid S. Miller <davem@davemloft.net>2016-11-18 13:58:39 -0500
commit06a77b07e3b44aea2b3c0e64de420ea2cfdcbaa9 (patch)
tree35be97e54af45ef40e4b8a1aea158c8c0ebd352b /net/unix
parentMerge branch 'cpsw-fixes' (diff)
af_unix: conditionally use freezable blocking calls in read
Commit 2b15af6f95 ("af_unix: use freezable blocking calls in read") converts schedule_timeout() to its freezable version, it was probably correct at that time, but later, commit 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix sockets") breaks the strong requirement for a freezable sleep, according to commit 0f9548ca1091: We shouldn't try_to_freeze if locks are held. Holding a lock can cause a deadlock if the lock is later acquired in the suspend or hibernate path (e.g. by dpm). Holding a lock can also cause a deadlock in the case of cgroup_freezer if a lock is held inside a frozen cgroup that is later acquired by a process outside that group. The pipe_lock is still held at that point. So use freezable version only for the recvmsg call path, avoid impact for Android. Fixes: 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix sockets") Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Colin Cross <ccross@android.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
1 files changed, 11 insertions, 6 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 5d1c14a2f268..2358f2690ec5 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2199,7 +2199,8 @@ out:
* Sleep until more data has arrived. But check for races..
static long unix_stream_data_wait(struct sock *sk, long timeo,
- struct sk_buff *last, unsigned int last_len)
+ struct sk_buff *last, unsigned int last_len,
+ bool freezable)
struct sk_buff *tail;
@@ -2220,7 +2221,10 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
- timeo = freezable_schedule_timeout(timeo);
+ if (freezable)
+ timeo = freezable_schedule_timeout(timeo);
+ else
+ timeo = schedule_timeout(timeo);
if (sock_flag(sk, SOCK_DEAD))
@@ -2250,7 +2254,8 @@ struct unix_stream_read_state {
unsigned int splice_flags;
-static int unix_stream_read_generic(struct unix_stream_read_state *state)
+static int unix_stream_read_generic(struct unix_stream_read_state *state,
+ bool freezable)
struct scm_cookie scm;
struct socket *sock = state->socket;
@@ -2330,7 +2335,7 @@ again:
timeo = unix_stream_data_wait(sk, timeo, last,
- last_len);
+ last_len, freezable);
if (signal_pending(current)) {
err = sock_intr_errno(timeo);
@@ -2472,7 +2477,7 @@ static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
.flags = flags
- return unix_stream_read_generic(&state);
+ return unix_stream_read_generic(&state, true);
static int unix_stream_splice_actor(struct sk_buff *skb,
@@ -2503,7 +2508,7 @@ static ssize_t unix_stream_splice_read(struct socket *sock, loff_t *ppos,
state.flags = MSG_DONTWAIT;
- return unix_stream_read_generic(&state);
+ return unix_stream_read_generic(&state, false);
static int unix_shutdown(struct socket *sock, int mode)