[PATCH] nvme-fc: fix the fc_appid_store return value

[PATCH] nvme-fc: fix the fc_appid_store return value

[Christoph Hellwig]

"nvme-fc: fold t fc_update_appid into fc_appid_store" accidentally
changed the userspace interface for the appid attribute, because the code
that decrements "count" to remove a trailing '\n' in the parsing results
in the decremented value being incorrectly be returned from the sysfs
write.  Fix this by keeping an orig_count variable for the full length
of the write.

Fixes: c814153c83a8 ("nvme-fc: fold t fc_update_appid into fc_appid_store")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: James Smart <jsmart2021@gmail.com>
Tested-by:  Muneendra Kumar M <muneendra.kumar@broadcom.com>
---
 drivers/nvme/host/fc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 8d14df8eeab84..127abaf9ba5d6 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3880,6 +3880,7 @@ static int fc_parse_cgrpid(const char *buf, u64 *id)
 static ssize_t fc_appid_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
+	size_t orig_count = count;
 	u64 cgrp_id;
 	int appid_len = 0;
 	int cgrpid_len = 0;
@@ -3904,7 +3905,7 @@ static ssize_t fc_appid_store(struct device *dev,
 	ret = blkcg_set_fc_appid(app_id, cgrp_id, sizeof(app_id));
 	if (ret < 0)
 		return ret;
-	return count;
+	return orig_count;
 }
 static DEVICE_ATTR(appid_store, 0200, NULL, fc_appid_store);
 #endif /* CONFIG_BLK_CGROUP_FC_APPID */
-- 
2.30.2

Re: [PATCH] nvme-fc: fix the fc_appid_store return value

[Chaitanya Kulkarni]

On 8/6/22 01:32, Christoph Hellwig wrote:
> "nvme-fc: fold t fc_update_appid into fc_appid_store" accidentally
> changed the userspace interface for the appid attribute, because the code
> that decrements "count" to remove a trailing '\n' in the parsing results
> in the decremented value being incorrectly be returned from the sysfs
> write.  Fix this by keeping an orig_count variable for the full length
> of the write.
> 
> Fixes: c814153c83a8 ("nvme-fc: fold t fc_update_appid into fc_appid_store")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Ewan D. Milne <emilne@redhat.com>
> Reviewed-by: James Smart <jsmart2021@gmail.com>
> Tested-by:  Muneendra Kumar M <muneendra.kumar@broadcom.com>
> ---


Looks good.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCH] nvme-fc: fix the fc_appid_store return value

[Chaitanya Kulkarni]

On 8/6/22 01:32, Christoph Hellwig wrote:
> "nvme-fc: fold t fc_update_appid into fc_appid_store" accidentally
> changed the userspace interface for the appid attribute, because the code
> that decrements "count" to remove a trailing '\n' in the parsing results
> in the decremented value being incorrectly be returned from the sysfs
> write.  Fix this by keeping an orig_count variable for the full length
> of the write.
> 
>

while we are at it perhaps we should consider fixing following ?

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 8d14df8eeab8..7ba35b059214 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3886,10 +3886,10 @@ static ssize_t fc_appid_store(struct device *dev,
         char app_id[FC_APPID_LEN];
         int ret = 0;

-       if (buf[count-1] == '\n')
+       if (buf[count - 1] == '\n')
                 count--;

-       if ((count > (16+1+FC_APPID_LEN)) || (!strchr(buf, ':')))
+       if ((count > (16 + 1 + FC_APPID_LEN)) || (!strchr(buf, ':')))
                 return -EINVAL;

         cgrpid_len = fc_parse_cgrpid(buf, &cgrp_id);
@@ -3900,7 +3900,7 @@ static ssize_t fc_appid_store(struct device *dev,
                 return -EINVAL;

         memset(app_id, 0x0, sizeof(app_id));
-       memcpy(app_id, &buf[cgrpid_len+1], appid_len);
+       memcpy(app_id, &buf[cgrpid_len + 1], appid_len);
         ret = blkcg_set_fc_appid(app_id, cgrp_id, sizeof(app_id));
         if (ret < 0)
                 return ret;

or lmk if I should send a different patch..

-ck

Re: [PATCH] nvme-fc: fix the fc_appid_store return value

[Christoph Hellwig]

On Sun, Aug 07, 2022 at 09:23:27AM +0000, Chaitanya Kulkarni wrote:
> while we are at it perhaps we should consider fixing following ?

Yes, please send a separate patch.  Please also remove the various
pointless braces in the hunk that you are touching.

Re: [PATCH] nvme-fc: fix the fc_appid_store return value

[Sagi Grimberg]

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>