[v2] libceph: Avoid holding the zero page on ceph_msgr_slab_init errors

Commit Message

Benoît Canet June 25, 2015, 7:02 p.m. UTC

ceph_msgr_slab_init may fail due to a temporary ENOMEM.

Delay a bit the initialization of zero_page in ceph_msgr_init and
reorder it's cleanup in _ceph_msgr_exit so it's done in reverse
order of setup.

BUG_ON() will not suffer to be postponed in case it is triggered.

Signed-off-by: Benoît Canet <[e-mail]>
Reviewed-by: Alex Elder <[e-mail]>
---
 net/ceph/messenger.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Patch

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 38f06a4..ec68cd3 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -275,22 +275,22 @@  static void _ceph_msgr_exit(void)
 		ceph_msgr_wq = NULL;
 	}
 
-	ceph_msgr_slab_exit();
-
 	BUG_ON(zero_page == NULL);
 	page_cache_release(zero_page);
 	zero_page = NULL;
+
+	ceph_msgr_slab_exit();
 }
 
 int ceph_msgr_init(void)
 {
+	if (ceph_msgr_slab_init())
+		return -ENOMEM;
+
 	BUG_ON(zero_page != NULL);
 	zero_page = ZERO_PAGE(0);
 	page_cache_get(zero_page);
 
-	if (ceph_msgr_slab_init())
-		return -ENOMEM;
-
 	/*
 	 * The number of active work items is limited by the number of
 	 * connections, so leave @max_active at default.