Hi,
On 11-07-18 16:52, Steven Rostedt wrote:
On Wed, 11 Jul 2018 16:46:11 +0200 Thomas Zimmermann tzimmermann@suse.de 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@goodmis.org Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Reviewed-by: Sergey Senozhatsky sergey.senozhatsky@gmail.com Signed-off-by: Hans de Goede hdegoede@redhat.com
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);