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Date: Thu, 21 Oct 2021 16:56:11 +0800
From: Xin Hao <xhao@...ux.alibaba.com>
To: sjpark@...zon.de
Cc: xhao@...ux.alibaba.com, akpm@...ux-foundation.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mm/damon/dbgfs: Optimize target_ids interface write operation
When writing some pids to target_ids interface, calling scanf()
to get 'id' may be failed. If the value of '*nr_ids' is 0 at this time,
there is no need to return 'ids' here, we just need to release it and
return NULL pointer to improve related code operation efficiency.
Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
---
mm/damon/dbgfs.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index a02cf6bee8e8..2d77bf579ffb 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -308,21 +308,25 @@ static unsigned long *str_to_target_ids(const char *str, ssize_t len,
unsigned long *ids;
const int max_nr_ids = 32;
unsigned long id;
- int pos = 0, parsed, ret;
+ int pos = 0, parsed;
*nr_ids = 0;
ids = kmalloc_array(max_nr_ids, sizeof(id), GFP_KERNEL);
if (!ids)
return NULL;
while (*nr_ids < max_nr_ids && pos < len) {
- ret = sscanf(&str[pos], "%lu%n", &id, &parsed);
- pos += parsed;
- if (ret != 1)
+ if (sscanf(&str[pos], "%lu%n", &id, &parsed) != 1)
break;
+ pos += parsed;
ids[*nr_ids] = id;
*nr_ids += 1;
}
+ if (!*nr_ids) {
+ kfree(ids);
+ return NULL;
+ }
+
return ids;
}
--
2.31.0
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