Convert buffer output to use sysfs_emit/sysfs_emit_at API for safer
PAGE_SIZE handling and standardized sysfs output.

Signed-off-by: Abdelrahman Fekry <abdelrahmanfekry375@gmail.com>
---
v2:
- Change the place of ssize_t offset.
- Addressing a possible change in behaviour if sysfs_emit fails.
v1: https://lore.kernel.org/all/20250621062944.168386-1-abdelrahmanfekry375@gmail.com/
- Convert scnprintf with sysfs_emit/sysfs_emit_at in bo_show func.
 drivers/staging/media/atomisp/pci/hmm/hmm.c | 25 +++++++--------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm.c b/drivers/staging/media/atomisp/pci/hmm/hmm.c
index 84102c3aaf97..b5d0516e36dc 100644
--- a/drivers/staging/media/atomisp/pci/hmm/hmm.c
+++ b/drivers/staging/media/atomisp/pci/hmm/hmm.c
@@ -37,51 +37,42 @@ static const char hmm_bo_type_string[] = "pv";
 static ssize_t bo_show(struct device *dev, struct device_attribute *attr,
 		       char *buf, struct list_head *bo_list, bool active)
 {
-	ssize_t ret = 0;
 	struct hmm_buffer_object *bo;
 	unsigned long flags;
 	int i;
 	long total[HMM_BO_LAST] = { 0 };
 	long count[HMM_BO_LAST] = { 0 };
-	int index1 = 0;
-	int index2 = 0;
+	ssize_t offset = 0;
 
-	ret = scnprintf(buf, PAGE_SIZE, "type pgnr\n");
-	if (ret <= 0)
-		return 0;
-
-	index1 += ret;
+	/* Changing to sysfs_emit changes the behaviour if failed*/
+	offset += sysfs_emit(buf, "type pgnr\n");
 
 	spin_lock_irqsave(&bo_device.list_lock, flags);
 	list_for_each_entry(bo, bo_list, list) {
 		if ((active && (bo->status & HMM_BO_ALLOCED)) ||
 		    (!active && !(bo->status & HMM_BO_ALLOCED))) {
-			ret = scnprintf(buf + index1, PAGE_SIZE - index1,
+			offset += sysfs_emit_at(buf, offset,
 					"%c %d\n",
 					hmm_bo_type_string[bo->type], bo->pgnr);
 
 			total[bo->type] += bo->pgnr;
 			count[bo->type]++;
-			if (ret > 0)
-				index1 += ret;
 		}
 	}
 	spin_unlock_irqrestore(&bo_device.list_lock, flags);
 
 	for (i = 0; i < HMM_BO_LAST; i++) {
 		if (count[i]) {
-			ret = scnprintf(buf + index1 + index2,
-					PAGE_SIZE - index1 - index2,
+			offset += sysfs_emit_at(buf,
+					offset,
 					"%ld %c buffer objects: %ld KB\n",
 					count[i], hmm_bo_type_string[i],
 					total[i] * 4);
-			if (ret > 0)
-				index2 += ret;
 		}
 	}
 
-	/* Add trailing zero, not included by scnprintf */
-	return index1 + index2 + 1;
+	/* Direct return of accumulated length */
+	return offset;
 }
 
 static ssize_t active_bo_show(struct device *dev, struct device_attribute *attr,
-- 
2.25.1

On Sun, Jun 22, 2025 at 9:54 AM Abdelrahman Fekry
<abdelrahmanfekry375@gmail.com> wrote:
>
> Convert buffer output to use sysfs_emit/sysfs_emit_at API for safer
> PAGE_SIZE handling and standardized sysfs output.

...

> +       /* Changing to sysfs_emit changes the behaviour if failed*/

This comment, besides missing the space, is useless here. You need to
use the comment block for the proposed change.

> +       offset += sysfs_emit(buf, "type pgnr\n");


-- 
With Best Regards,
Andy Shevchenko

On Sun, Jun 22, 2025 at 11:37 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Sun, Jun 22, 2025 at 9:54 AM Abdelrahman Fekry
> <abdelrahmanfekry375@gmail.com> wrote:

...

> > +       /* Changing to sysfs_emit changes the behaviour if failed*/
>
> This comment, besides missing the space, is useless here. You need to
> use the comment block for the proposed change.

Also the text of the comment is a noise. You need to explain better
what's going on here.

-- 
With Best Regards,
Andy Shevchenko

On Sun, Jun 22, 2025 at 11:39 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Sun, Jun 22, 2025 at 11:37 PM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
> > On Sun, Jun 22, 2025 at 9:54 AM Abdelrahman Fekry
> > <abdelrahmanfekry375@gmail.com> wrote:
>
> ...
>
> > > +       /* Changing to sysfs_emit changes the behaviour if failed*/
> >
> > This comment, besides missing the space, is useless here. You need to
> > use the comment block for the proposed change.
>
> Also the text of the comment is a noise. You need to explain better
> what's going on here.
>
Sorry for the mess, so the comment is enough if well written or i
should do something else?
Thanks!
> --
> With Best Regards,
> Andy Shevchenko

On Sun, Jun 22, 2025 at 9:54 AM Abdelrahman Fekry
<abdelrahmanfekry375@gmail.com> wrote:
>
> Convert buffer output to use sysfs_emit/sysfs_emit_at API for safer
> PAGE_SIZE handling and standardized sysfs output.

...

> v2:

> - Addressing a possible change in behaviour if sysfs_emit fails.

I don't see it being done. Can you elaborate, please?

-- 
With Best Regards,
Andy Shevchenko