From: Xin Wang x.wang@intel.com
[ Upstream commit 6884d2051011f4db9e2f0b85709c79a8ced13bd6 ]
It is generally expected that the write() function should return a positive value indicating the number of bytes written or a negative error code if an error occurs. Returning 0 is unusual and can lead to unexpected behavior.
When the user program writes the same value to wedged_mode twice in a row, a lockup will occur, because the value expected to be returned by the write() function inside the program should be equal to the actual written value instead of 0.
To reproduce the issue: echo 1 > /sys/kernel/debug/dri/0/wedged_mode echo 1 > /sys/kernel/debug/dri/0/wedged_mode <- lockup here
Signed-off-by: Xin Wang x.wang@intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Fei Yang fei.yang@intel.com Cc: Shuicheng Lin shuicheng.lin@intel.com Reviewed-by: Rodrigo Vivi rodrigo.vivi@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20250213223615.2327367-1-x.wan... Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/xe/xe_debugfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c index 492b4877433f1..6bfdd3a9913fd 100644 --- a/drivers/gpu/drm/xe/xe_debugfs.c +++ b/drivers/gpu/drm/xe/xe_debugfs.c @@ -166,7 +166,7 @@ static ssize_t wedged_mode_set(struct file *f, const char __user *ubuf, return -EINVAL;
if (xe->wedged.mode == wedged_mode) - return 0; + return size;
xe->wedged.mode = wedged_mode;