From: Liu Bo <bo.liu@linux.alibaba.com>
Date: Fri, 29 Jun 2018 09:56:08 +0800
Subject: [PATCH] Blktrace: bail out early if block debugfs is not configured
Git-commit: e1a413245a564683697a3d02ec197b72cf009b89
Patch-mainline: v4.19-rc1
References: bsc#1104967,FATE#325924
Since @blk_debugfs_root couldn't be configured dynamically, we can
save a few memory allocation if it's not there.
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
kernel/trace/blktrace.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 987d9a9ae283..b951aa1fac61 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -494,6 +494,9 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;
+ if (!blk_debugfs_root)
+ return -ENOENT;
+
strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
@@ -518,9 +521,6 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
ret = -ENOENT;
- if (!blk_debugfs_root)
- goto err;
-
dir = debugfs_lookup(buts->name, blk_debugfs_root);
if (!dir)
bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
--
2.16.4