Hi,
On 11-07-18 16:52, Steven Rostedt wrote:
On Wed, 11 Jul 2018 16:46:11 +0200
Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
Hi
Am 28.06.2018 um 11:03 schrieb Hans de Goede:
Replace comments about places where the console lock should be held with
calls to WARN_CONSOLE_UNLOCKED() to assert that it is actually held.
Debugging fbcon sometimes requires to not take the console lock. This
patch breaks the debugging workaround provided by
'fb.lockless_register_fb'. The dmesg is now filled with warnings about
the missing lock.
What if you make lockless_register_fb visible to fbcon, and then we can
have a macro:
#define WARN_FB_CONSOLE_UNLOCKED() \
do { \
if (unlikely(!lockless_register_fb)) \
WARN_CONSOLE_UNLOCKED(); \
} while (0)
And use that instead?
Yes I'm already preparing a patch like that :)
Without the unlikely though, this is not used in hot paths.
Regards,
Hans
-- Steve
Best regards
Thomas
Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v3:
-New patch in v3 of this patchset
Changes in v4:
-Keep the comments about which fbcon functions need locks in place
---
drivers/video/fbdev/core/fbcon.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index c910e74d46ff..cd8d52a967aa 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -828,6 +828,8 @@ static int set_con2fb_map(int unit, int newidx, int user)
struct fb_info *oldinfo = NULL;
int found, err = 0;
+ WARN_CONSOLE_UNLOCKED();
+
if (oldidx == newidx)
return 0;
@@ -3044,6 +3046,8 @@ static int fbcon_fb_unbind(int idx)
{
int i, new_idx = -1, ret = 0;
+ WARN_CONSOLE_UNLOCKED();
+
if (!fbcon_has_console_bind)
return 0;
@@ -3094,6 +3098,8 @@ static int fbcon_fb_unregistered(struct fb_info *info)
{
int i, idx;
+ WARN_CONSOLE_UNLOCKED();
+
idx = info->node;
for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map[i] == idx)
@@ -3131,6 +3137,9 @@ static int fbcon_fb_unregistered(struct fb_info *info)
static void fbcon_remap_all(int idx)
{
int i;
+
+ WARN_CONSOLE_UNLOCKED();
+
for (i = first_fb_vc; i <= last_fb_vc; i++)
set_con2fb_map(i, idx, 0);
@@ -3177,6 +3186,8 @@ static int fbcon_fb_registered(struct fb_info *info)
{
int ret = 0, i, idx;
+ WARN_CONSOLE_UNLOCKED();
+
idx = info->node;
fbcon_select_primary(info);
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