Re: [PATCH] powerpc/qspinlock: Add spinlock contention tracepoint
From: Christophe Leroy <hidden>
Date: 2025-07-30 07:20:34
Also in:
lkml
Le 25/07/2025 à 10:14, Nysal Jan K.A. a écrit :
quoted hunk ↗ jump to hunk
Add a lock contention tracepoint in the queued spinlock slowpath. Also add the __lockfunc annotation so that in_lock_functions() works as expected. Signed-off-by: Nysal Jan K.A. <redacted> --- arch/powerpc/lib/qspinlock.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c index bcc7e4dff8c3..622e7f45c2ce 100644 --- a/arch/powerpc/lib/qspinlock.c +++ b/arch/powerpc/lib/qspinlock.c@@ -9,6 +9,7 @@ #include <linux/sched/clock.h> #include <asm/qspinlock.h> #include <asm/paravirt.h> +#include <trace/events/lock.h> #define MAX_NODES 4@@ -708,8 +709,9 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b qnodesp->count--; } -void queued_spin_lock_slowpath(struct qspinlock *lock) +void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock) { + trace_contention_begin(lock, LCB_F_SPIN); /* * This looks funny, but it induces the compiler to inline both * sides of the branch rather than share code as when the condition@@ -718,16 +720,17 @@ void queued_spin_lock_slowpath(struct qspinlock *lock) if (IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) && is_shared_processor()) { if (try_to_steal_lock(lock, true)) { spec_barrier(); - return; + } else { + queued_spin_lock_mcs_queue(lock, true);
If I read correctly, now all this is single line so you have to drop the braces , see https://docs.kernel.org/process/coding-style.html#placing-braces-and-spaces
}
- queued_spin_lock_mcs_queue(lock, true);
} else {
if (try_to_steal_lock(lock, false)) {
spec_barrier();
- return;
+ } else {
+ queued_spin_lock_mcs_queue(lock, false);
}Same here.
- queued_spin_lock_mcs_queue(lock, false); } + trace_contention_end(lock, 0); } EXPORT_SYMBOL(queued_spin_lock_slowpath);