diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-05-19 12:20:59 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-06-05 21:11:03 +0200 |
| commit | d16317de9b412aa7bd3598c607112298e36b4352 (patch) | |
| tree | 977e3a5e3befafc5121fc66e1399ab2909beeb82 /kernel/time/timekeeping.c | |
| parent | 8f2d6c41e5a649fe217724364cbb1a7d2e6ff205 (diff) | |
seqlock/latch: Provide raw_read_seqcount_latch_retry()
The read side of seqcount_latch consists of:
do {
seq = raw_read_seqcount_latch(&latch->seq);
...
} while (read_seqcount_latch_retry(&latch->seq, seq));
which is asymmetric in the raw_ department, and sure enough,
read_seqcount_latch_retry() includes (explicit) instrumentation where
raw_read_seqcount_latch() does not.
This inconsistency becomes a problem when trying to use it from
noinstr code. As such, fix it by renaming and re-implementing
raw_read_seqcount_latch_retry() without the instrumentation.
Specifically the instrumentation in question is kcsan_atomic_next(0)
in do___read_seqcount_retry(). Loosing this annotation is not a
problem because raw_read_seqcount_latch() does not pass through
kcsan_atomic_next(KCSAN_SEQLOCK_REGION_MAX).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.233598176@infradead.org
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 09d594900ee0..266d02809dbb 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -450,7 +450,7 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf) tkr = tkf->base + (seq & 0x01); now = ktime_to_ns(tkr->base); now += fast_tk_get_delta_ns(tkr); - } while (read_seqcount_latch_retry(&tkf->seq, seq)); + } while (raw_read_seqcount_latch_retry(&tkf->seq, seq)); return now; } @@ -566,7 +566,7 @@ static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) basem = ktime_to_ns(tkr->base); baser = ktime_to_ns(tkr->base_real); delta = fast_tk_get_delta_ns(tkr); - } while (read_seqcount_latch_retry(&tkf->seq, seq)); + } while (raw_read_seqcount_latch_retry(&tkf->seq, seq)); if (mono) *mono = basem + delta; |