locking: Apply contention tracepoints in the slow path

Adding the lock contention tracepoints in various lock function slow
paths.  Note that each arch can define spinlock differently, I only
added it only to the generic qspinlock for now.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Link: https://lkml.kernel.org/r/20220322185709.141236-3-namhyung@kernel.org

1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index ec36b73f4733..7f42e52a648f 100644
--- a/kernel/locking/qrwlock.c
+++ b/kernel/locking/qrwlock.c
@@ -12,6 +12,7 @@
 #include <linux/percpu.h>
 #include <linux/hardirq.h>
 #include <linux/spinlock.h>
+#include <trace/events/lock.h>
 
 /**
  * queued_read_lock_slowpath - acquire read lock of a queue rwlock
@@ -34,6 +35,8 @@ void queued_read_lock_slowpath(struct qrwlock *lock)
 	}
 	atomic_sub(_QR_BIAS, &lock->cnts);
 
+	trace_contention_begin(lock, LCB_F_SPIN | LCB_F_READ);
+
 	/*
 	 * Put the reader into the wait queue
 	 */
@@ -51,6 +54,8 @@ void queued_read_lock_slowpath(struct qrwlock *lock)
 	 * Signal the next one in queue to become queue head
 	 */
 	arch_spin_unlock(&lock->wait_lock);
+
+	trace_contention_end(lock, 0);
 }
 EXPORT_SYMBOL(queued_read_lock_slowpath);
 
@@ -62,6 +67,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
 {
 	int cnts;
 
+	trace_contention_begin(lock, LCB_F_SPIN | LCB_F_WRITE);
+
 	/* Put the writer into the wait queue */
 	arch_spin_lock(&lock->wait_lock);
 
@@ -79,5 +86,7 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
 	} while (!atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED));
 unlock:
 	arch_spin_unlock(&lock->wait_lock);
+
+	trace_contention_end(lock, 0);
 }
 EXPORT_SYMBOL(queued_write_lock_slowpath);