In update_alloc_hint_after_get, we wrap the new hint back to 0 one bit
too early. This breaks round robin tag allocation (BLK_MQ_F_TAG_RR) -
some tags get skipped, so we don't get round robin tags even in the
simple case of single-threaded load on a single hctx. Fix the off-by-one
in the wrapping condition so that round robin tag allocation works
properly.
The same pattern occurs in __sbitmap_get_word, so fix it there too.
Signed-off-by: Uday Shankar <ushankar@xxxxxxxxxxxxxxx>
---
lib/sbitmap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index d3412984170c03dc6600bbe53f130404b765ac5a..aa1cec78b9649f1f3e8ef2d617dd7ee724391a8c 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -51,7 +51,7 @@ static inline void update_alloc_hint_after_get(struct sbitmap *sb,
} else if (nr == hint || unlikely(sb->round_robin)) {
/* Only update the hint if we used it. */
hint = nr + 1;
- if (hint >= depth - 1)
+ if (hint >= depth)
hint = 0;
this_cpu_write(*sb->alloc_hint, hint);
}
@@ -182,7 +182,7 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
break;
hint = nr + 1;
- if (hint >= depth - 1)
+ if (hint >= depth)
hint = 0;
}
--
2.34.1
