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authorPeter Zijlstra <peterz@infradead.org>2023-05-19 12:20:59 +0200
committerPeter Zijlstra <peterz@infradead.org>2023-06-05 21:11:03 +0200
commitd16317de9b412aa7bd3598c607112298e36b4352 (patch)
tree977e3a5e3befafc5121fc66e1399ab2909beeb82 /kernel/printk/printk.c
parent8f2d6c41e5a649fe217724364cbb1a7d2e6ff205 (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/printk/printk.c')
-rw-r--r--kernel/printk/printk.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6a333adce3b3..357a4d18f638 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -528,7 +528,7 @@ static u64 latched_seq_read_nolock(struct latched_seq *ls)
seq = raw_read_seqcount_latch(&ls->latch);
idx = seq & 0x1;
val = ls->val[idx];
- } while (read_seqcount_latch_retry(&ls->latch, seq));
+ } while (raw_read_seqcount_latch_retry(&ls->latch, seq));
return val;
}