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rcu: Make kfree_rcu() ignore NULL pointers

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This commit makes the kfree_rcu() macro's semantics be consistent
with the likes of kfree() by adding a check for NULL pointers, so
that kfree_rcu(NULL, ...) is a no-op.

Reported-by: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Paul E. McKenney 2019-04-09 07:48:18 -07:00
parent 3ae976a7e3
commit 12edff045b
1 changed files with 8 additions and 4 deletions
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12
include/linux/rcupdate.h
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@ -805,7 +805,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
/**
* kfree_rcu() - kfree an object after a grace period.
* @ptr: pointer to kfree
* @rcu_head: the name of the struct rcu_head within the type of @ptr.
* @rhf: the name of the struct rcu_head within the type of @ptr.
*
* Many rcu callbacks functions just call kfree() on the base structure.
* These functions are trivial, but their size adds up, and furthermore
@ -828,9 +828,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
* The BUILD_BUG_ON check must not involve any function calls, hence the
* checks are done in macros here.
*/
#define kfree_rcu(ptr, rcu_head) \
__kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
#define kfree_rcu(ptr, rhf) \
do { \
typeof (ptr) ___p = (ptr); \
\
if (___p) \
__kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
} while (0)
/*
* Place this after a lock-acquisition primitive to guarantee that