[PATCH] s390/spinlock: Add contention tracepoints to lock slowpath

[PATCH] s390/spinlock: Add contention tracepoints to lock slowpath

[Ciunas Bennett]

Instrument arch_spin_lock_wait() with trace_contention_begin() and
trace_contention_end().

These tracepoints are used by lock contention analysis tools such as
perf lock contention to identify contended locks and measure wait times.
Both the generic implementation and powerpc emit the same events from
their spinlock slow path.

Place the tracepoints in arch_spin_lock_wait(), which is only entered
when lock acquisition falls back to the contention path.

Signed-off-by: Ciunas Bennett <ciunas@linux.ibm.com>
---
 arch/s390/lib/spinlock.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index 10db1e56a811..dbabca35c008 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -18,6 +18,7 @@
 #include <asm/alternative.h>
 #include <asm/machine.h>
 #include <asm/asm.h>
+#include <trace/events/lock.h>
 
 int spin_retry = -1;
 
@@ -281,10 +282,12 @@ static inline void arch_spin_lock_classic(arch_spinlock_t *lp)
 
 void arch_spin_lock_wait(arch_spinlock_t *lp)
 {
+	trace_contention_begin(lp, LCB_F_SPIN);
 	if (test_cpu_flag(CIF_DEDICATED_CPU))
 		arch_spin_lock_queued(lp);
 	else
 		arch_spin_lock_classic(lp);
+	trace_contention_end(lp, 0);
 }
 EXPORT_SYMBOL(arch_spin_lock_wait);
 

base-commit: 1590cf0329716306e948a8fc29f1d3ee87d3989f
-- 
2.54.0

Re: [PATCH] s390/spinlock: Add contention tracepoints to lock slowpath

[sashiko-bot]

> Instrument arch_spin_lock_wait() with trace_contention_begin() and
> trace_contention_end().
> 
> These tracepoints are used by lock contention analysis tools such as
> perf lock contention to identify contended locks and measure wait times.
> Both the generic implementation and powerpc emit the same events from
> their spinlock slow path.
> 
> Place the tracepoints in arch_spin_lock_wait(), which is only entered
> when lock acquisition falls back to the contention path.
> 
> Signed-off-by: Ciunas Bennett <ciunas@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260723084229.923353-1-ciunas@linux.ibm.com?part=1

Re: [PATCH] s390/spinlock: Add contention tracepoints to lock slowpath

[Heiko Carstens]

On Thu, Jul 23, 2026 at 10:42:29AM +0200, Ciunas Bennett wrote:
> Instrument arch_spin_lock_wait() with trace_contention_begin() and
> trace_contention_end().
> 
> These tracepoints are used by lock contention analysis tools such as
> perf lock contention to identify contended locks and measure wait times.
> Both the generic implementation and powerpc emit the same events from
> their spinlock slow path.
> 
> Place the tracepoints in arch_spin_lock_wait(), which is only entered
> when lock acquisition falls back to the contention path.
> 
> Signed-off-by: Ciunas Bennett <ciunas@linux.ibm.com>
> ---
>  arch/s390/lib/spinlock.c | 3 +++
>  1 file changed, 3 insertions(+)

Acked-by: Heiko Carstens <hca@linux.ibm.com>

Re: [PATCH] s390/spinlock: Add contention tracepoints to lock slowpath

[Vasily Gorbik]

On Thu, Jul 23, 2026 at 10:42:29AM +0200, Ciunas Bennett wrote:
> Instrument arch_spin_lock_wait() with trace_contention_begin() and
> trace_contention_end().
> 
> These tracepoints are used by lock contention analysis tools such as
> perf lock contention to identify contended locks and measure wait times.
> Both the generic implementation and powerpc emit the same events from
> their spinlock slow path.
> 
> Place the tracepoints in arch_spin_lock_wait(), which is only entered
> when lock acquisition falls back to the contention path.
> 
> Signed-off-by: Ciunas Bennett <ciunas@linux.ibm.com>
> ---
>  arch/s390/lib/spinlock.c | 3 +++
>  1 file changed, 3 insertions(+)

Applied, thank you!