[PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[Ewan D. Milne]

This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.

The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into fc_appid_store"
changed the userspace interface, 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 revering the commit.

Cc: stable@vger.kernel.org
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
---
 drivers/nvme/host/fc.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 9987797620b6..27f6dfad5d3b 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3873,10 +3873,12 @@ static int fc_parse_cgrpid(const char *buf, u64 *id)
 }
 
 /*
- * Parse and update the appid in the blkcg associated with the cgroupid.
+ * fc_update_appid: Parse and update the appid in the blkcg associated with
+ * cgroupid.
+ * @buf: buf contains both cgrpid and appid info
+ * @count: size of the buffer
  */
-static ssize_t fc_appid_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
+static int fc_update_appid(const char *buf, size_t count)
 {
 	u64 cgrp_id;
 	int appid_len = 0;
@@ -3904,6 +3906,17 @@ static ssize_t fc_appid_store(struct device *dev,
 		return ret;
 	return count;
 }
+
+static ssize_t fc_appid_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int ret  = 0;
+
+	ret = fc_update_appid(buf, count);
+	if (ret < 0)
+		return -EINVAL;
+	return count;
+}
 static DEVICE_ATTR(appid_store, 0200, NULL, fc_appid_store);
 #endif /* CONFIG_BLK_CGROUP_FC_APPID */
 
-- 
2.20.1

Re: [PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[Christoph Hellwig]

On Mon, Aug 01, 2022 at 12:27:13PM -0400, Ewan D. Milne wrote:
> This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.
> 
> The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into fc_appid_store"
> changed the userspace interface, 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 revering the commit.

Wouldn't something like the patch below be much simpler and cleaner:


diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 9987797620b6d..e24ab688f00d5 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3878,6 +3878,7 @@ 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;
@@ -3902,7 +3903,7 @@ 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 */

Re: [PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[James Smart]

On 8/1/2022 11:27 AM, Christoph Hellwig wrote:
> On Mon, Aug 01, 2022 at 12:27:13PM -0400, Ewan D. Milne wrote:
>> This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.
>>
>> The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into fc_appid_store"
>> changed the userspace interface, 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 revering the commit.
> 
> Wouldn't something like the patch below be much simpler and cleaner:
> 
> 
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 9987797620b6d..e24ab688f00d5 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -3878,6 +3878,7 @@ 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;
> @@ -3902,7 +3903,7 @@ 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 */
> 

Reviewed-by: James Smart <jsmart2021@gmail.com>

looks good on my end.

-- james

RE: [PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[Muneendra Kumar M]

[-- Attachment #1: Type: text/plain, Size: 2773 bytes --]

I have tested the below changes suggested by Christoph and it is working as
expected.


Tested-by: <muneendra.kumar@broadcom.com>



-----Original Message-----
From: James Smart [mailto:jsmart2021@gmail.com]
Sent: Tuesday, August 2, 2022 2:33 AM
To: Christoph Hellwig <hch@lst.de>; Ewan D. Milne <emilne@redhat.com>
Cc: linux-nvme@lists.infradead.org; muneendra.kumar@broadcom.com;
james.smart@broadcom.com; stable@vger.kernel.org
Subject: Re: [PATCH] Revert "nvme-fc: fold t fc_update_appid into
fc_appid_store"

On 8/1/2022 11:27 AM, Christoph Hellwig wrote:
> On Mon, Aug 01, 2022 at 12:27:13PM -0400, Ewan D. Milne wrote:
>> This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.
>>
>> The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into
>> fc_appid_store"
>> changed the userspace interface, 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
>> revering the commit.
>
> Wouldn't something like the patch below be much simpler and cleaner:
>
>
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c index
> 9987797620b6d..e24ab688f00d5 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -3878,6 +3878,7 @@ 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;
> @@ -3902,7 +3903,7 @@ 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 */
>

Reviewed-by: James Smart <jsmart2021@gmail.com>

looks good on my end.

-- james

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Re: [PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[Ewan D. Milne]

On Wed, 2022-08-03 at 10:08 +0530, Muneendra Kumar M wrote:
> I have tested the below changes suggested by Christoph and it is working as
> expected.
> 
> 
> Tested-by: <muneendra.kumar@broadcom.com>
> 

Fine with me.

Reviewed-by: Ewan D. Milne <emilne@redhat.com>