linux-kernel - [PATCH v1] HID: debug: Use the __set_current

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Message-Id: <20250509022554.27001-1-zhangzihuan@kylinos.cn>
Date: Fri,  9 May 2025 10:25:54 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: jikos@...nel.org,
	bentiss@...nel.org
Cc: linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zihuan Zhang <zhangzihuan@...inos.cn>
Subject: [PATCH v1] HID: debug: Use the __set_current_state()

When detecting an invalid list->hdev, the process needs to manually set
its state to TASK_RUNNING and exit. In the original code,
set_current_state() (which includes a memory barrier) is used here, but
it is immediately followed by a mutex_unlock() call. Since
mutex_unlock() internally includes a memory barrier, this ensures that
all modifications within the critical section (including the process
state) are visible to other CPUs. Therefore, replacing it with
__set_current_state() (without an implicit barrier) avoids redundant
memory barriers.

Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
---
 drivers/hid/hid-debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 8433306148d5..00a73983ef19 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -3726,7 +3726,7 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer,
 			 */
 			if (!list->hdev || !list->hdev->debug) {
 				ret = -EIO;
-				set_current_state(TASK_RUNNING);
+				__set_current_state(TASK_RUNNING);
 				goto out;
 			}

-- 
2.25.1