Re: [PATCH v3 1/4] HID: hid-picolcd*: Convert sprintf/scnprintf to sysfs_emit/sysfs_emit_at

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Le 18/03/2024 à 02:28, Li Zhijian a écrit :
Per filesystems/sysfs.rst, show() should only use sysfs_emit()
or sysfs_emit_at() when formatting the value to be returned to user space.

coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().

scnprintf() will be converted as weel if they have.

Generally, this patch is generated by
make coccicheck M=<path/to/file> MODE=patch \
COCCI=scripts/coccinelle/api/device_attr_show.cocci

No functional change intended

CC: "Bruno Prémont" <bonbons@xxxxxxxxxxxxxxxxx>
CC: Jiri Kosina <jikos@xxxxxxxxxx>
CC: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
CC: linux-input@xxxxxxxxxxxxxxx
Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
---
V3:
    Covert more file(drivers/hid/hid-picolcd_fb.c) as suggested by Bruno

This is a part of the work "Fix coccicheck device_attr_show warnings"[1]
Split them per subsystem so that the maintainer can review it easily
[1] https://lore.kernel.org/lkml/20240116041129.3937800-1-lizhijian@xxxxxxxxxxx/
Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
---
  drivers/hid/hid-picolcd_core.c | 6 +++---
  drivers/hid/hid-picolcd_fb.c   | 4 ++--
  2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/hid-picolcd_core.c b/drivers/hid/hid-picolcd_core.c
index bbda231a7ce3..fa46fb6eab3f 100644
--- a/drivers/hid/hid-picolcd_core.c
+++ b/drivers/hid/hid-picolcd_core.c
@@ -256,9 +256,9 @@ static ssize_t picolcd_operation_mode_show(struct device *dev,
  	struct picolcd_data *data = dev_get_drvdata(dev);
if (data->status & PICOLCD_BOOTLOADER)
-		return snprintf(buf, PAGE_SIZE, "[bootloader] lcd\n");
+		return sysfs_emit(buf, "[bootloader] lcd\n");
  	else
-		return snprintf(buf, PAGE_SIZE, "bootloader [lcd]\n");
+		return sysfs_emit(buf, "bootloader [lcd]\n");
  }
static ssize_t picolcd_operation_mode_store(struct device *dev,
@@ -301,7 +301,7 @@ static ssize_t picolcd_operation_mode_delay_show(struct device *dev,
  {
  	struct picolcd_data *data = dev_get_drvdata(dev);
- return snprintf(buf, PAGE_SIZE, "%hu\n", data->opmode_delay);
+	return sysfs_emit(buf, "%hu\n", data->opmode_delay);
  }
static ssize_t picolcd_operation_mode_delay_store(struct device *dev,
diff --git a/drivers/hid/hid-picolcd_fb.c b/drivers/hid/hid-picolcd_fb.c
index d7dddd99d325..369c78d70e66 100644
--- a/drivers/hid/hid-picolcd_fb.c
+++ b/drivers/hid/hid-picolcd_fb.c
@@ -424,9 +424,9 @@ static ssize_t picolcd_fb_update_rate_show(struct device *dev,

Hi,

just above we have:
	for (i = 1; i <= PICOLCDFB_UPDATE_RATE_LIMIT; i++)

  		if (ret >= PAGE_SIZE)
  			break;

and PICOLCDFB_UPDATE_RATE_LIMIT is 10, so it is not possible to have ret >= PAGE_SIZE. Should it happen, sysfs_emit_at() handles it.
So, this test can also be removed, IMHO.

CJ

  		else if (i == fb_update_rate)
-			ret += scnprintf(buf+ret, PAGE_SIZE-ret, "[%u] ", i);
+			ret += sysfs_emit_at(buf, ret, "[%u] ", i);
  		else
-			ret += scnprintf(buf+ret, PAGE_SIZE-ret, "%u ", i);
+			ret += sysfs_emit_at(buf, ret, "%u ", i);
  	if (ret > 0)
  		buf[min(ret, (size_t)PAGE_SIZE)-1] = '\n';
  	return ret;





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