diff mbox

drm/sysfs: Grab lock for edid/modes_show

Message ID 1443783662-23066-1-git-send-email-daniel.vetter@ffwll.ch
State New, archived
Headers show

Commit Message

Daniel Vetter Oct. 2, 2015, 11:01 a.m. UTC
We chase pointers/lists without taking the locks protecting them,
which isn't that good.

Fix it.

v2: Actually unlock properly, spotted by Julia.

v3: Put the label _before_ the mutex_unlock (Emil)

Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/drm_sysfs.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

Comments

Emil Velikov Oct. 2, 2015, 12:08 p.m. UTC | #1
On 2 October 2015 at 12:01, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> We chase pointers/lists without taking the locks protecting them,
> which isn't that good.
>
> Fix it.
>
> v2: Actually unlock properly, spotted by Julia.
>
> v3: Put the label _before_ the mutex_unlock (Emil)
>
> Cc: Emil Velikov <emil.l.velikov@gmail.com>
> Cc: Julia Lawall <julia.lawall@lip6.fr>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Patch does exactly what it says on the tin.

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

-Emil
Daniel Vetter Nov. 19, 2015, 4:22 p.m. UTC | #2
On Fri, Oct 02, 2015 at 01:08:40PM +0100, Emil Velikov wrote:
> On 2 October 2015 at 12:01, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > We chase pointers/lists without taking the locks protecting them,
> > which isn't that good.
> >
> > Fix it.
> >
> > v2: Actually unlock properly, spotted by Julia.
> >
> > v3: Put the label _before_ the mutex_unlock (Emil)
> >
> > Cc: Emil Velikov <emil.l.velikov@gmail.com>
> > Cc: Julia Lawall <julia.lawall@lip6.fr>
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Patch does exactly what it says on the tin.
> 
> Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

Applied to drm-misc, thanks.
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 7506de0a75b4..8ceb1cb6166a 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -261,23 +261,29 @@  static ssize_t edid_show(struct file *filp, struct kobject *kobj,
 	struct drm_connector *connector = to_drm_connector(connector_dev);
 	unsigned char *edid;
 	size_t size;
+	ssize_t ret = 0;
 
+	mutex_lock(&connector->dev->mode_config.mutex);
 	if (!connector->edid_blob_ptr)
-		return 0;
+		goto unlock;
 
 	edid = connector->edid_blob_ptr->data;
 	size = connector->edid_blob_ptr->length;
 	if (!edid)
-		return 0;
+		goto unlock;
 
 	if (off >= size)
-		return 0;
+		goto unlock;
 
 	if (off + count > size)
 		count = size - off;
 	memcpy(buf, edid + off, count);
 
-	return count;
+	ret = count;
+unlock:
+	mutex_unlock(&connector->dev->mode_config.mutex);
+
+	return ret;
 }
 
 static ssize_t modes_show(struct device *device,
@@ -288,10 +294,12 @@  static ssize_t modes_show(struct device *device,
 	struct drm_display_mode *mode;
 	int written = 0;
 
+	mutex_lock(&connector->dev->mode_config.mutex);
 	list_for_each_entry(mode, &connector->modes, head) {
 		written += snprintf(buf + written, PAGE_SIZE - written, "%s\n",
 				    mode->name);
 	}
+	mutex_unlock(&connector->dev->mode_config.mutex);
 
 	return written;
 }