From 0cd1ef8b0877fce91ebe138e895bf228c618beef Mon Sep 17 00:00:00 2001 From: Anders Roxell Date: Mon, 27 May 2019 09:51:54 +0200 Subject: [PATCH] seqlock: mark functions as __always_inline to not be traceable With the function graph tracer, each traced function calls sched_clock() through trace_clock_local(), or it can call __ktime_get_fast_ns() through ktime_get_mono_fast_ns(); to take a timestamp. We must ensure that these functions raw_read_seqcount()/read_seqcount_retry() and raw_read_seqcount_latch()/read_seqcount_retry() do not in turn trigger the graph tracer. All 4 functions is marked as inline. However, if CONFIG_OPTIMIZE_INLINING is set that may make the two functions tracable which they shouldn't. Rework so that functions that can call either sched_clock() through trace_clock_local, or call __ktime_get_fast_ns() through ktime_get_mono_fast_ns(), are marked with __always_inline would annotate both raw_read_seqcount()/read_seqcount_retry() and raw_read_seqcount_latch()/read_seqcount_retry(). They will now be inlined even if CONFIG_OPTIMIZE_INLINING is turned on. Acked-by: Will Deacon Signed-off-by: Anders Roxell --- include/linux/seqlock.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 0491d963d47e..06cc474fb79e 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -127,7 +127,7 @@ static inline unsigned __read_seqcount_begin(const seqcount_t *s) * seqcount without any lockdep checking and without checking or * masking the LSB. Calling code is responsible for handling that. */ -static inline unsigned raw_read_seqcount(const seqcount_t *s) +static __always_inline unsigned raw_read_seqcount(const seqcount_t *s) { unsigned ret = READ_ONCE(s->sequence); smp_rmb(); @@ -200,7 +200,8 @@ static inline unsigned raw_seqcount_begin(const seqcount_t *s) * Use carefully, only in critical code, and comment how the barrier is * provided. */ -static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) +static +inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) { return unlikely(s->sequence != start); } @@ -215,7 +216,8 @@ static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) * If the critical section was invalid, it must be ignored (and typically * retried). */ -static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) +static +__always_inline int read_seqcount_retry(const seqcount_t *s, unsigned start) { smp_rmb(); return __read_seqcount_retry(s, start); @@ -276,7 +278,7 @@ static inline void raw_write_seqcount_barrier(seqcount_t *s) s->sequence++; } -static inline int raw_read_seqcount_latch(seqcount_t *s) +static __always_inline int raw_read_seqcount_latch(seqcount_t *s) { /* Pairs with the first smp_wmb() in raw_write_seqcount_latch() */ int seq = READ_ONCE(s->sequence); /* ^^^ */ -- 2.20.1