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authorLinus Torvalds <torvalds@linux-foundation.org>2016-09-02 00:43:53 +0300
committerDavid S. Miller <davem@davemloft.net>2016-09-04 23:29:29 +0300
commit6e1ce3c3451291142a57c4f3f6f999a29fb5b3bc (patch)
tree44c5431d3f3ee9b9cffe3415f0b359091f52efff /include
parent38f7bd94a97b542de86a2be9229289717e33a7a4 (diff)
downloadlinux-6e1ce3c3451291142a57c4f3f6f999a29fb5b3bc.tar.xz
af_unix: split 'u->readlock' into two: 'iolock' and 'bindlock'
Right now we use the 'readlock' both for protecting some of the af_unix IO path and for making the bind be single-threaded. The two are independent, but using the same lock makes for a nasty deadlock due to ordering with regards to filesystem locking. The bind locking would want to nest outside the VSF pathname locking, but the IO locking wants to nest inside some of those same locks. We tried to fix this earlier with commit c845acb324aa ("af_unix: Fix splice-bind deadlock") which moved the readlock inside the vfs locks, but that caused problems with overlayfs that will then call back into filesystem routines that take the lock in the wrong order anyway. Splitting the locks means that we can go back to having the bind lock be the outermost lock, and we don't have any deadlocks with lock ordering. Acked-by: Rainer Weikusat <rweikusat@cyberadapt.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/af_unix.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 9b4c418bebd8..fd60eccb59a6 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -52,7 +52,7 @@ struct unix_sock {
struct sock sk;
struct unix_address *addr;
struct path path;
- struct mutex readlock;
+ struct mutex iolock, bindlock;
struct sock *peer;
struct list_head link;
atomic_long_t inflight;