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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-06-19 14:57:10 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-06-23 11:19:29 -0700
commit546a9d8519ed137b2804a3f5a3659003039dd49c (patch)
tree1f4c679c28b2980e08bc1d0bb8c0b01dc6d98247 /include/linux/rcupdate.h
parent7171511eaec5bf23fb06078f59784a3a0626b38f (diff)
rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()
Currently, call_rcu() relies on implicit allocation and initialization for the debug-objects handling of RCU callbacks. If you hammer the kernel hard enough with Sasha's modified version of trinity, you can end up with the sl*b allocators recursing into themselves via this implicit call_rcu() allocation. This commit therefore exports the debug_init_rcu_head() and debug_rcu_head_free() functions, which permits the allocators to allocated and pre-initialize the debug-objects information, so that there no longer any need for call_rcu() to do that initialization, which in turn prevents the recursion into the memory allocators. Reported-by: Sasha Levin <sasha.levin@oracle.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Looks-good-to: Christoph Lameter <cl@linux.com>
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 5a75d19aa661..13bbfbde41b9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -358,9 +358,19 @@ void wait_rcu_gp(call_rcu_func_t crf);
* initialization.
*/
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+void init_rcu_head(struct rcu_head *head);
+void destroy_rcu_head(struct rcu_head *head);
void init_rcu_head_on_stack(struct rcu_head *head);
void destroy_rcu_head_on_stack(struct rcu_head *head);
#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+static inline void init_rcu_head(struct rcu_head *head)
+{
+}
+
+static inline void destroy_rcu_head(struct rcu_head *head)
+{
+}
+
static inline void init_rcu_head_on_stack(struct rcu_head *head)
{
}