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: v3.12.31~29
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f8af8eeb8306a965973c3061630d6975cab5e76c;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>
Cc: Neil Brown <nfbrown@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 2ffebf2081ceb..27d7f27425926 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -113,7 +113,7 @@ __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;
 }