perf rwsem: Add debug mode that uses a mutex

Mutex error check will capture trying to take the lock recursively and
other problems that rwlock won't. At the expense of concurrency, adda
debug mode that uses a mutex in place of a rwsem.

Signed-off-by: Ian Rogers <[email protected]>
Cc: K Prateek Nayak <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: German Gomez <[email protected]>
Cc: James Clark <[email protected]>
Cc: Nick Terrell <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Changbin Du <[email protected]>
Cc: liuwenyu <[email protected]>
Cc: Yang Jihong <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Kajol Jain <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Yanteng Si <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

2 files changed, 45 insertions, 0 deletions

diff --git a/tools/perf/util/rwsem.c b/tools/perf/util/rwsem.c
index f3d29d8ddc99..5109167f27f7 100644
--- a/tools/perf/util/rwsem.c
+++ b/tools/perf/util/rwsem.c
@@ -2,32 +2,66 @@
 #include "util.h"
 #include "rwsem.h"
 
+#if RWS_ERRORCHECK
+#include "mutex.h"
+#endif
+
 int init_rwsem(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_init(&sem->mtx);
+	return 0;
+#else
 	return pthread_rwlock_init(&sem->lock, NULL);
+#endif
 }
 
 int exit_rwsem(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_destroy(&sem->mtx);
+	return 0;
+#else
 	return pthread_rwlock_destroy(&sem->lock);
+#endif
 }
 
 int down_read(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_lock(&sem->mtx);
+	return 0;
+#else
 	return perf_singlethreaded ? 0 : pthread_rwlock_rdlock(&sem->lock);
+#endif
 }
 
 int up_read(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_unlock(&sem->mtx);
+	return 0;
+#else
 	return perf_singlethreaded ? 0 : pthread_rwlock_unlock(&sem->lock);
+#endif
 }
 
 int down_write(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_lock(&sem->mtx);
+	return 0;
+#else
 	return perf_singlethreaded ? 0 : pthread_rwlock_wrlock(&sem->lock);
+#endif
 }
 
 int up_write(struct rw_semaphore *sem)
 {
+#if RWS_ERRORCHECK
+	mutex_unlock(&sem->mtx);
+	return 0;
+#else
 	return perf_singlethreaded ? 0 : pthread_rwlock_unlock(&sem->lock);
+#endif
 }
diff --git a/tools/perf/util/rwsem.h b/tools/perf/util/rwsem.h
index 94565ad4d494..ef5cbc31d967 100644
--- a/tools/perf/util/rwsem.h
+++ b/tools/perf/util/rwsem.h
@@ -2,9 +2,20 @@
 #define _PERF_RWSEM_H
 
 #include <pthread.h>
+#include "mutex.h"
+
+/*
+ * Mutexes have additional error checking. Enable to use a mutex rather than a
+ * rwlock for debugging.
+ */
+#define RWS_ERRORCHECK 0
 
 struct rw_semaphore {
+#if RWS_ERRORCHECK
+	struct mutex mtx;
+#else
 	pthread_rwlock_t lock;
+#endif
 };
 
 int init_rwsem(struct rw_semaphore *sem);