Re: [PATCH] video: Fix return value of fb_notifier_call_chain

On 11/22/2011 12:58 AM, Joonyoung Shim wrote:

11/22/2011 08:08 AM, Florian Tobias Schandinat 쓴 글:

quoted

On 11/21/2011 06:55 AM, Joonyoung Shim wrote:

quoted

The return value of blocking_notifier_call_chain isn't errno value, it
is just notify return value. The ret of fb_notifier_call_chain should is
restored to error value from notify return value using
notifier_to_errno().

If I'm not wrong this patch would rather break things than fix them. As I
understand the notifier_calls would be required to encode the return
value with
notifier_from_errno. This does not happen at the moment for fb
clients, for
example fbcon_event_notify in drivers/video/console/fbcon.c, so this
patch would
screw up the return values, I think.

OK, but it is wrong to return error value than notify value many
callback of fb notify clients and some fb notify clients returns notify
value, please see sh_mobile_lcdc_notify() and sh_hdmi_notify().

We should use only one, notify value or error value, i think it's right
to use notify value.

I agree. But all fb clients need to be checked and fixed up if needed at the
same time you do the change you proposed, otherwise things are likely to break.

$ grep -r fb_register_client .
./include/linux/fb.h:extern int fb_register_client(struct notifier_block *nb);
./arch/arm/mach-pxa/am200epd.c: fb_register_client(&am200_fb_notif);
./drivers/leds/ledtrig-backlight.c:     ret = fb_register_client(&n->notifier);
./drivers/video/sh_mobile_hdmi.c:       fb_register_client(&hdmi->notifier);
./drivers/video/fb_notify.c: *  fb_register_client - register a client notifier
./drivers/video/fb_notify.c:int fb_register_client(struct notifier_block *nb)
./drivers/video/fb_notify.c:EXPORT_SYMBOL(fb_register_client);
./drivers/video/console/fbcon.c:        fb_register_client(&fbcon_event_notifier);
./drivers/video/sh_mobile_lcdcfb.c:     fb_register_client(&priv->notifier);
./drivers/video/omap/omapfb_main.c:int omapfb_register_client(struct
omapfb_notifier_block *omapfb_nb,
./drivers/video/omap/omapfb_main.c:EXPORT_SYMBOL(omapfb_register_client);
./drivers/video/omap/omapfb.h:extern int  omapfb_register_client(struct
omapfb_notifier_block *nb,
./drivers/video/backlight/backlight.c:  return fb_register_client(&bd->fb_notif);
./drivers/video/backlight/lcd.c:        return fb_register_client(&ld->fb_notif);
./drivers/staging/olpc_dcon/olpc_dcon.c:
fb_register_client(&dcon->fbevent_nb);


Best regards,

Florian Tobias Schandinat

Thanks.

quoted

Best regards,

Florian Tobias Schandinat

quoted

Signed-off-by: Joonyoung Shim<redacted>
---
  drivers/video/fb_notify.c |    4 +++-
  1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/video/fb_notify.c b/drivers/video/fb_notify.c
index 74c2da5..49a64a3 100644
--- a/drivers/video/fb_notify.c
+++ b/drivers/video/fb_notify.c

@@ -42,6 +42,8 @@ EXPORT_SYMBOL(fb_unregister_client);
   */
  int fb_notifier_call_chain(unsigned long val, void *v)
  {
-    return blocking_notifier_call_chain(&fb_notifier_list, val, v);
+    int ret = blocking_notifier_call_chain(&fb_notifier_list, val, v);
+
+    return notifier_to_errno(ret);
  }
  EXPORT_SYMBOL_GPL(fb_notifier_call_chain);