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?
-- 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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