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-rw-r--r--include/linux/percpu-rwsem.h10
-rw-r--r--lib/percpu-rwsem.c21
2 files changed, 26 insertions, 5 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index d2146a4f833e..3e88c9a7d57f 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -5,6 +5,7 @@
#include <linux/rwsem.h>
#include <linux/percpu.h>
#include <linux/wait.h>
+#include <linux/lockdep.h>
struct percpu_rw_semaphore {
unsigned int __percpu *fast_read_ctr;
@@ -20,7 +21,14 @@ extern void percpu_up_read(struct percpu_rw_semaphore *);
extern void percpu_down_write(struct percpu_rw_semaphore *);
extern void percpu_up_write(struct percpu_rw_semaphore *);
-extern int percpu_init_rwsem(struct percpu_rw_semaphore *);
+extern int __percpu_init_rwsem(struct percpu_rw_semaphore *,
+ const char *, struct lock_class_key *);
extern void percpu_free_rwsem(struct percpu_rw_semaphore *);
+#define percpu_init_rwsem(brw) \
+({ \
+ static struct lock_class_key rwsem_key; \
+ __percpu_init_rwsem(brw, #brw, &rwsem_key); \
+})
+
#endif
diff --git a/lib/percpu-rwsem.c b/lib/percpu-rwsem.c
index ce92ab563a08..652a8ee8efe9 100644
--- a/lib/percpu-rwsem.c
+++ b/lib/percpu-rwsem.c
@@ -2,18 +2,21 @@
#include <linux/rwsem.h>
#include <linux/percpu.h>
#include <linux/wait.h>
+#include <linux/lockdep.h>
#include <linux/percpu-rwsem.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/errno.h>
-int percpu_init_rwsem(struct percpu_rw_semaphore *brw)
+int __percpu_init_rwsem(struct percpu_rw_semaphore *brw,
+ const char *name, struct lock_class_key *rwsem_key)
{
brw->fast_read_ctr = alloc_percpu(int);
if (unlikely(!brw->fast_read_ctr))
return -ENOMEM;
- init_rwsem(&brw->rw_sem);
+ /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
+ __init_rwsem(&brw->rw_sem, name, rwsem_key);
atomic_set(&brw->write_ctr, 0);
atomic_set(&brw->slow_read_ctr, 0);
init_waitqueue_head(&brw->write_waitq);
@@ -66,19 +69,29 @@ static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val)
/*
* Like the normal down_read() this is not recursive, the writer can
* come after the first percpu_down_read() and create the deadlock.
+ *
+ * Note: returns with lock_is_held(brw->rw_sem) == T for lockdep,
+ * percpu_up_read() does rwsem_release(). This pairs with the usage
+ * of ->rw_sem in percpu_down/up_write().
*/
void percpu_down_read(struct percpu_rw_semaphore *brw)
{
- if (likely(update_fast_ctr(brw, +1)))
+ might_sleep();
+ if (likely(update_fast_ctr(brw, +1))) {
+ rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
return;
+ }
down_read(&brw->rw_sem);
atomic_inc(&brw->slow_read_ctr);
- up_read(&brw->rw_sem);
+ /* avoid up_read()->rwsem_release() */
+ __up_read(&brw->rw_sem);
}
void percpu_up_read(struct percpu_rw_semaphore *brw)
{
+ rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_);
+
if (likely(update_fast_ctr(brw, -1)))
return;
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