[PATCH] knfsd: fix a race in closing NFSd connections
If you lose this race, it can iput a socket inode twice and you get a BUG
in fs/inode.c
When I added the option for user-space to close a socket, I added some
cruft to svc_delete_socket so that I could call that function when closing
a socket per user-space request.
This was the wrong thing to do. I should have just set SK_CLOSE and let
normal mechanisms do the work.
Not only wrong, but buggy. The locking is all wrong and it openned up a
race where-by a socket could be closed twice.
So this patch:
Introduces svc_close_socket which sets SK_CLOSE then either leave
the close up to a thread, or calls svc_delete_socket if it can
get SK_BUSY.
Adds a bias to sk_busy which is removed when SK_DEAD is set,
This avoid races around shutting down the socket.
Changes several 'spin_lock' to 'spin_lock_bh' where the _bh
was missing.
Bugzilla-url: http://bugzilla.kernel.org/show_bug.cgi?id=7916
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 4c16112..c1f8781 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -386,7 +386,7 @@
svsk = list_entry(serv->sv_tempsocks.next,
struct svc_sock,
sk_list);
- svc_delete_socket(svsk);
+ svc_close_socket(svsk);
}
if (serv->sv_shutdown)
serv->sv_shutdown(serv);
@@ -395,7 +395,7 @@
svsk = list_entry(serv->sv_permsocks.next,
struct svc_sock,
sk_list);
- svc_delete_socket(svsk);
+ svc_close_socket(svsk);
}
cache_clean_deferred(serv);