linux-kernel - [PATCH 1/2] firewire: Kill unnecessary buf check in device

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Date: Mon, 22 Jan 2024 13:39:41 +0800
From: Li Zhijian <lizhijian@...itsu.com>
To: linux-kernel@...r.kernel.org
Cc: Takashi Sakamoto <o-takashi@...amocchi.jp>,
	linux1394-devel@...ts.sourceforge.net,
	Li Zhijian <lizhijian@...itsu.com>
Subject: [PATCH 1/2] firewire: Kill unnecessary buf check in device_attribute.show

Per Documentation/filesystems/sysfs.rst:
> sysfs allocates a buffer of size (PAGE_SIZE) and passes it to the
> method.

So we can kill the unnecessary buf check safely.

Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
 drivers/firewire/core-device.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 0547253d16fe..47d6cb3dc916 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -323,7 +323,7 @@ static ssize_t show_immediate(struct device *dev,
 	if (value < 0)
 		return -ENOENT;
 
-	return snprintf(buf, buf ? PAGE_SIZE : 0, "0x%06x\n", value);
+	return snprintf(buf, PAGE_SIZE, "0x%06x\n", value);
 }
 
 #define IMMEDIATE_ATTR(name, key)				\
@@ -335,8 +335,6 @@ static ssize_t show_text_leaf(struct device *dev,
 	struct config_rom_attribute *attr =
 		container_of(dattr, struct config_rom_attribute, attr);
 	const u32 *directories[] = {NULL, NULL};
-	size_t bufsize;
-	char dummy_buf[2];
 	int i, ret = -ENOENT;
 
 	down_read(&fw_device_rwsem);
@@ -358,15 +356,9 @@ static ssize_t show_text_leaf(struct device *dev,
 		}
 	}
 
-	if (buf) {
-		bufsize = PAGE_SIZE - 1;
-	} else {
-		buf = dummy_buf;
-		bufsize = 1;
-	}
-
 	for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) {
-		int result = fw_csr_string(directories[i], attr->key, buf, bufsize);
+		int result = fw_csr_string(directories[i], attr->key, buf,
+					   PAGE_SIZE - 1);
 		// Detected.
 		if (result >= 0)
 			ret = result;
-- 
2.29.2