From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Tobias Schandinat Date: Tue, 22 Nov 2011 01:20:27 +0000 Subject: Re: [PATCH] video: Fix return value of fb_notifier_call_chain Message-Id: <4ECAF8DB.4020909@gmx.de> List-Id: References: <1321858524-19368-1-git-send-email-jy0922.shim@samsung.com> <4ECAD9F0.9050508@gmx.de> <4ECAF3C6.4010507@samsung.com> In-Reply-To: <4ECAF3C6.4010507@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Joonyoung Shim Cc: linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org On 11/22/2011 12:58 AM, Joonyoung Shim wrote: > 11/22/2011 08:08 AM, Florian Tobias Schandinat 쓴 글: >> On 11/21/2011 06:55 AM, Joonyoung Shim wrote: >>> 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. > >> >> Best regards, >> >> Florian Tobias Schandinat >> >>> Signed-off-by: Joonyoung Shim >>> --- >>> 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); >> > >