2021-12-23 02:24:23

by 王擎

Subject: [PATCH] block: return specific error when pointer is NULL

From: Wang Qing <[email protected]>

loop_attr_backing_file_show() better return specific error than 0
when pointer is NULL

Signed-off-by: Wang Qing <[email protected]>
---
drivers/block/loop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e52a8a5..860a5b6
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -667,7 +667,7 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
spin_unlock_irq(&lo->lo_lock);

if (IS_ERR_OR_NULL(p))
- ret = PTR_ERR(p);
+ ret = p ? PTR_ERR(p) : -ENOENT;
else {
ret = strlen(p);
memmove(buf, p, ret);
--
2.7.4

2021-12-23 08:57:35

by Christoph Hellwig

Subject: Re: [PATCH] block: return specific error when pointer is NULL

On Wed, Dec 22, 2021 at 06:24:03PM -0800, Qing Wang wrote:
> From: Wang Qing <[email protected]>
>
> loop_attr_backing_file_show() better return specific error than 0
> when pointer is NULL

Well, let's turn this into something that is not butt ugly then:

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7f4ea06534c2d..b9ee0a165b75e 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -666,15 +666,15 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
spin_unlock_irq(&lo->lo_lock);

- if (IS_ERR_OR_NULL(p))
- ret = PTR_ERR(p);
- else {
- ret = strlen(p);
- memmove(buf, p, ret);
- buf[ret++] = '\n';
- buf[ret] = 0;
- }
-
+ if (!p)
+ return -ENOENT;
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+
+ ret = strlen(p);
+ memmove(buf, p, ret);
+ buf[ret++] = '\n';
+ buf[ret] = 0;
return ret;
}