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tracing/lock: Use TRACE_EVENT_FN() for contended_release

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queued_spin_unlock() gates its contended_release trace call behind a
static branch, so a NOP sits on the unlock path even while the
tracepoint is disabled. Removing that requires replacing the unlock
implementation only while contended_release is enabled, which needs a
callback when the tracepoint is toggled.

Convert contended_release to TRACE_EVENT_FN() and add weak no-op
arch_contended_release_trace_reg()/arch_contended_release_trace_unreg()
hooks.

The default hooks are empty, so this is a no-op until an architecture
overrides them.

No functional change intended.

Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juergen Gross <jgross@suse.com>
Link: https://patch.msgid.link/1c2fcccfb584c075c02890c484f22c76a1948bf1.1785778551.git.d@ilvokhin.com
This commit is contained in:
Dmitry Ilvokhin
2026-08-04 07:15:44 +00:00
committed by Peter Zijlstra
parent f7e2cb6d49
commit b359800c69
2 changed files with 12 additions and 2 deletions
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10
include/trace/events/lock.h
View File

@@ -137,7 +137,11 @@ TRACE_EVENT(contention_end,
TP_printk("%p (ret=%d)", __entry->lock_addr, __entry->ret)
);
TRACE_EVENT(contended_release,
/* kernel/locking/mutex.c */
int arch_contended_release_trace_reg(void);
void arch_contended_release_trace_unreg(void);
TRACE_EVENT_FN(contended_release,
TP_PROTO(void *lock),
@@ -151,7 +155,9 @@ TRACE_EVENT(contended_release,
__entry->lock_addr = lock;
),
TP_printk("%p", __entry->lock_addr)
TP_printk("%p", __entry->lock_addr),
arch_contended_release_trace_reg, arch_contended_release_trace_unreg
);
#endif /* _TRACE_LOCK_H */

4
kernel/locking/mutex.c
View File

@@ -1272,6 +1272,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(contention_begin);
EXPORT_TRACEPOINT_SYMBOL_GPL(contention_end);
EXPORT_TRACEPOINT_SYMBOL_GPL(contended_release);
__weak int arch_contended_release_trace_reg(void) { return 0; }
__weak void arch_contended_release_trace_unreg(void) { }
/**
* atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
* @cnt: the atomic which we are to dec