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-rw-r--r--lib/refcount.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/lib/refcount.c b/lib/refcount.c
index ebcf8cd49e05..6e904af0fb3e 100644
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -33,6 +33,9 @@
* Note that the allocator is responsible for ordering things between free()
* and alloc().
*
+ * The decrements dec_and_test() and sub_and_test() also provide acquire
+ * ordering on success.
+ *
*/
#include <linux/mutex.h>
@@ -164,8 +167,8 @@ EXPORT_SYMBOL(refcount_inc_checked);
* at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
- * before, and provides a control dependency such that free() must come after.
- * See the comment on top.
+ * before, and provides an acquire ordering on success such that free()
+ * must come after.
*
* Use of this function is not recommended for the normal reference counting
* use case in which references are taken and released one at a time. In these
@@ -190,7 +193,12 @@ bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r)
} while (!atomic_try_cmpxchg_release(&r->refs, &val, new));
- return !new;
+ if (!new) {
+ smp_acquire__after_ctrl_dep();
+ return true;
+ }
+ return false;
+
}
EXPORT_SYMBOL(refcount_sub_and_test_checked);
@@ -202,8 +210,8 @@ EXPORT_SYMBOL(refcount_sub_and_test_checked);
* decrement when saturated at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
- * before, and provides a control dependency such that free() must come after.
- * See the comment on top.
+ * before, and provides an acquire ordering on success such that free()
+ * must come after.
*
* Return: true if the resulting refcount is 0, false otherwise
*/