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authorOleg Nesterov <oleg@redhat.com>2015-08-21 19:42:55 +0200
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-10-06 11:25:26 -0700
commit95b19f684c61ffc9b039e02c5d1113c2d8cd7105 (patch)
tree5faf2eee589b2acb438a0881c2c3d80877f96bd5 /kernel/locking/percpu-rwsem.c
parent07899a6e5f56136028c44a57ad0451e797365ac3 (diff)
locking/percpu-rwsem: Make percpu_free_rwsem() after kzalloc() safe
This is the temporary ugly hack which will be reverted later. We only need it to ensure that the next patch will not break "change sb_writers to use percpu_rw_semaphore" patches routed via the VFS tree. The alloc_super()->destroy_super() error path assumes that it is safe to call percpu_free_rwsem() after kzalloc() without percpu_init_rwsem(), so let's not disappoint it. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/locking/percpu-rwsem.c')
-rw-r--r--kernel/locking/percpu-rwsem.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index e2621fbbcbd1..9529a30ec57b 100644
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -26,6 +26,13 @@ EXPORT_SYMBOL_GPL(__percpu_init_rwsem);
void percpu_free_rwsem(struct percpu_rw_semaphore *brw)
{
+ /*
+ * XXX: temporary kludge. The error path in alloc_super()
+ * assumes that percpu_free_rwsem() is safe after kzalloc().
+ */
+ if (!brw->fast_read_ctr)
+ return;
+
free_percpu(brw->fast_read_ctr);
brw->fast_read_ctr = NULL; /* catch use after free bugs */
}