From: David Jeffery <djeffery@redhat.com>
Date: Tue, 5 Aug 2014 15:19:42 +0000 (-0400)
Subject: nfs: Don't busy-wait on SIGKILL in __nfs_iocounter_wait
X-Git-Tag: v3.16.35~3466
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=e312624fb45f28ca57bf69470f79a35f1f41eb58;p=thirdparty%2Fkernel%2Fstable.git

nfs: Don't busy-wait on SIGKILL in __nfs_iocounter_wait

commit 92a56555bd576c61b27a5cab9f38a33a1e9a1df5 upstream.

If a SIGKILL is sent to a task waiting in __nfs_iocounter_wait,
it will busy-wait or soft lockup in its while loop.
nfs_wait_bit_killable won't sleep, and the loop won't exit on
the error return.

Stop the busy-wait by breaking out of the loop when
nfs_wait_bit_killable returns an error.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
[ kamal: backport to 3.13-stable: context ]
Cc: Moritz Mühlenhoff <muehlenhoff@univention.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 3a9c34a0f898b..54d049f930f7c 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -116,7 +116,7 @@ __nfs_iocounter_wait(struct nfs_io_counter *c)
 		if (atomic_read(&c->io_count) == 0)
 			break;
 		ret = nfs_wait_bit_killable(&c->flags);
-	} while (atomic_read(&c->io_count) != 0);
+	} while (atomic_read(&c->io_count) != 0 && !ret);
 	finish_wait(wq, &q.wait);
 	return ret;
 }