| Message ID | 20110618111934.26203dbf@neptune.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
ping Guennadi, I really want this issue fixed. Please have a look at Bruno's patch otherwise your driver might remain or get even more broken... I am scheduling Herton's patch for the next merge window. Regards, Florian Tobias Schandinat On 06/18/2011 09:19 AM, Bruno Prémont wrote: > Guennadi, could you have a look at (completely untested) patch which avoids > possible deadlock due to inverted lock taking order on hotplug as well > as "readding" lock_fb_info() for fb_set_suspend() call after Herton's > patch to fb_set_suspend(). > > Thanks, > Bruno > > > On Sat, 18 June 2011 Bruno Prémont <bonbons@linux-vserver.org> wrote: >> On Fri, 17 June 2011 Florian Tobias Schandinat <FlorianSchandinat@gmx.de> wrote: >>> From: Herton Ronaldo Krzesinski <herton@mandriva.com.br> >>> >>> A lock ordering issue can cause deadlocks: in framebuffer/console code, >>> all needed struct fb_info locks are taken before acquire_console_sem(), >>> in places which need to take console semaphore. >>> >>> But fb_set_suspend is always called with console semaphore held, and >>> inside it we call lock_fb_info which gets the fb_info lock, inverse >>> locking order of what the rest of the code does. This causes a real >>> deadlock issue, when we write to state fb sysfs attribute (which calls >>> fb_set_suspend) while a framebuffer is being unregistered by >>> remove_conflicting_framebuffers, as can be shown by following show >>> blocked state trace on a test program which loads i915 and runs another >>> forked processes writing to state attribute: >>> >>> Test process with semaphore held and trying to get fb_info lock: >> >> ... >> >>> fb-test2 which reproduces above is available on kernel.org bug #26232. >>> To solve this issue, avoid calling lock_fb_info inside fb_set_suspend, >>> and move it out to where needed (callers of fb_set_suspend must call >>> lock_fb_info before if needed). So far, the only place which needs to >>> call lock_fb_info is store_fbstate, all other places which calls >>> fb_set_suspend are suspend/resume hooks that should not need the lock as >>> they should be run only when processes are already frozen in >>> suspend/resume. >> >> From a quick look through FB drivers in 2.6.39 I've found one that would need >> more work: >> - drivers/video/sh_mobile_hdmi.c: sh_hdmi_edid_work_fn() >> Should get changed to >> a) right locking order in case (hdmi->hp_state == HDMI_HOTPLUG_CONNECTED) >> b) lock fb_info in the other case >> For this one fb_set_suspend() does get call in a hotplug worker, >> thus independently on suspend/resume process. >> >> The rest does match the suspend/resume hook pattern mentioned. >> >> Bruno >> >> >>> References: https://bugzilla.kernel.org/show_bug.cgi?id=26232 >>> Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br> >>> Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> >>> Cc: stable@kernel.org >>> --- >>> drivers/video/fbmem.c | 3 --- >>> drivers/video/fbsysfs.c | 3 +++ >>> 2 files changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c >>> index 5aac00e..ad93629 100644 >>> --- a/drivers/video/fbmem.c >>> +++ b/drivers/video/fbmem.c >>> @@ -1738,8 +1738,6 @@ void fb_set_suspend(struct fb_info *info, int state) >>> { >>> struct fb_event event; >>> >>> - if (!lock_fb_info(info)) >>> - return; >>> event.info = info; >>> if (state) { >>> fb_notifier_call_chain(FB_EVENT_SUSPEND, &event); >>> @@ -1748,7 +1746,6 @@ void fb_set_suspend(struct fb_info *info, int state) >>> info->state = FBINFO_STATE_RUNNING; >>> fb_notifier_call_chain(FB_EVENT_RESUME, &event); >>> } >>> - unlock_fb_info(info); >>> } >>> >>> /** >>> diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c >>> index 04251ce..67afa9c 100644 >>> --- a/drivers/video/fbsysfs.c >>> +++ b/drivers/video/fbsysfs.c >>> @@ -399,9 +399,12 @@ static ssize_t store_fbstate(struct device *device, >>> >>> state = simple_strtoul(buf, &last, 0); >>> >>> + if (!lock_fb_info(fb_info)) >>> + return -ENODEV; >>> console_lock(); >>> fb_set_suspend(fb_info, (int)state); >>> console_unlock(); >>> + unlock_fb_info(fb_info); >>> >>> return count; >>> } > > > diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c > index 2b9e56a..b1a13ab 100644 > --- a/drivers/video/sh_mobile_hdmi.c > +++ b/drivers/video/sh_mobile_hdmi.c > @@ -1151,27 +1151,27 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) > > ch = info->par; > > - console_lock(); > + if (lock_fb_info(info)) { > + console_lock(); > > - /* HDMI plug in */ > - if (!sh_hdmi_must_reconfigure(hdmi) && > - info->state == FBINFO_STATE_RUNNING) { > - /* > - * First activation with the default monitor - just turn > - * on, if we run a resume here, the logo disappears > - */ > - if (lock_fb_info(info)) { > + /* HDMI plug in */ > + if (!sh_hdmi_must_reconfigure(hdmi) && > + info->state == FBINFO_STATE_RUNNING) { > + /* > + * First activation with the default monitor - just turn > + * on, if we run a resume here, the logo disappears > + */ > info->var.width = hdmi->var.width; > info->var.height = hdmi->var.height; > sh_hdmi_display_on(hdmi, info); > - unlock_fb_info(info); > + } else { > + /* New monitor or have to wake up */ > + fb_set_suspend(info, 0); > } > - } else { > - /* New monitor or have to wake up */ > - fb_set_suspend(info, 0); > - } > > - console_unlock(); > + console_unlock(); > + unlock_fb_info(info); > + } > } else { > ret = 0; > if (!hdmi->info) > @@ -1181,12 +1181,15 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) > fb_destroy_modedb(hdmi->monspec.modedb); > hdmi->monspec.modedb = NULL; > > - console_lock(); > + if (lock_fb_info(info)) { > + console_lock(); > > - /* HDMI disconnect */ > - fb_set_suspend(hdmi->info, 1); > + /* HDMI disconnect */ > + fb_set_suspend(hdmi->info, 1); > > - console_unlock(); > + console_unlock(); > + unlock_fb_info(info); > + } > pm_runtime_put(hdmi->dev); > } > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Florian On Thu, 1 Sep 2011, Florian Tobias Schandinat wrote: > ping > > Guennadi, I really want this issue fixed. Please have a look at Bruno's patch > otherwise your driver might remain or get even more broken... Sorry, somehow this patch excaped my attention. Will test tomorrow. Thanks Guennadi > > I am scheduling Herton's patch for the next merge window. > > > Regards, > > Florian Tobias Schandinat > > > On 06/18/2011 09:19 AM, Bruno Prémont wrote: > > Guennadi, could you have a look at (completely untested) patch which avoids > > possible deadlock due to inverted lock taking order on hotplug as well > > as "readding" lock_fb_info() for fb_set_suspend() call after Herton's > > patch to fb_set_suspend(). > > > > Thanks, > > Bruno > > > > > > On Sat, 18 June 2011 Bruno Prémont <bonbons@linux-vserver.org> wrote: > >> On Fri, 17 June 2011 Florian Tobias Schandinat <FlorianSchandinat@gmx.de> wrote: > >>> From: Herton Ronaldo Krzesinski <herton@mandriva.com.br> > >>> > >>> A lock ordering issue can cause deadlocks: in framebuffer/console code, > >>> all needed struct fb_info locks are taken before acquire_console_sem(), > >>> in places which need to take console semaphore. > >>> > >>> But fb_set_suspend is always called with console semaphore held, and > >>> inside it we call lock_fb_info which gets the fb_info lock, inverse > >>> locking order of what the rest of the code does. This causes a real > >>> deadlock issue, when we write to state fb sysfs attribute (which calls > >>> fb_set_suspend) while a framebuffer is being unregistered by > >>> remove_conflicting_framebuffers, as can be shown by following show > >>> blocked state trace on a test program which loads i915 and runs another > >>> forked processes writing to state attribute: > >>> > >>> Test process with semaphore held and trying to get fb_info lock: > >> > >> ... > >> > >>> fb-test2 which reproduces above is available on kernel.org bug #26232. > >>> To solve this issue, avoid calling lock_fb_info inside fb_set_suspend, > >>> and move it out to where needed (callers of fb_set_suspend must call > >>> lock_fb_info before if needed). So far, the only place which needs to > >>> call lock_fb_info is store_fbstate, all other places which calls > >>> fb_set_suspend are suspend/resume hooks that should not need the lock as > >>> they should be run only when processes are already frozen in > >>> suspend/resume. > >> > >> From a quick look through FB drivers in 2.6.39 I've found one that would need > >> more work: > >> - drivers/video/sh_mobile_hdmi.c: sh_hdmi_edid_work_fn() > >> Should get changed to > >> a) right locking order in case (hdmi->hp_state == HDMI_HOTPLUG_CONNECTED) > >> b) lock fb_info in the other case > >> For this one fb_set_suspend() does get call in a hotplug worker, > >> thus independently on suspend/resume process. > >> > >> The rest does match the suspend/resume hook pattern mentioned. > >> > >> Bruno > >> > >> > >>> References: https://bugzilla.kernel.org/show_bug.cgi?id=26232 > >>> Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br> > >>> Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> > >>> Cc: stable@kernel.org > >>> --- > >>> drivers/video/fbmem.c | 3 --- > >>> drivers/video/fbsysfs.c | 3 +++ > >>> 2 files changed, 3 insertions(+), 3 deletions(-) > >>> > >>> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c > >>> index 5aac00e..ad93629 100644 > >>> --- a/drivers/video/fbmem.c > >>> +++ b/drivers/video/fbmem.c > >>> @@ -1738,8 +1738,6 @@ void fb_set_suspend(struct fb_info *info, int state) > >>> { > >>> struct fb_event event; > >>> > >>> - if (!lock_fb_info(info)) > >>> - return; > >>> event.info = info; > >>> if (state) { > >>> fb_notifier_call_chain(FB_EVENT_SUSPEND, &event); > >>> @@ -1748,7 +1746,6 @@ void fb_set_suspend(struct fb_info *info, int state) > >>> info->state = FBINFO_STATE_RUNNING; > >>> fb_notifier_call_chain(FB_EVENT_RESUME, &event); > >>> } > >>> - unlock_fb_info(info); > >>> } > >>> > >>> /** > >>> diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c > >>> index 04251ce..67afa9c 100644 > >>> --- a/drivers/video/fbsysfs.c > >>> +++ b/drivers/video/fbsysfs.c > >>> @@ -399,9 +399,12 @@ static ssize_t store_fbstate(struct device *device, > >>> > >>> state = simple_strtoul(buf, &last, 0); > >>> > >>> + if (!lock_fb_info(fb_info)) > >>> + return -ENODEV; > >>> console_lock(); > >>> fb_set_suspend(fb_info, (int)state); > >>> console_unlock(); > >>> + unlock_fb_info(fb_info); > >>> > >>> return count; > >>> } > > > > > > diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c > > index 2b9e56a..b1a13ab 100644 > > --- a/drivers/video/sh_mobile_hdmi.c > > +++ b/drivers/video/sh_mobile_hdmi.c > > @@ -1151,27 +1151,27 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) > > > > ch = info->par; > > > > - console_lock(); > > + if (lock_fb_info(info)) { > > + console_lock(); > > > > - /* HDMI plug in */ > > - if (!sh_hdmi_must_reconfigure(hdmi) && > > - info->state == FBINFO_STATE_RUNNING) { > > - /* > > - * First activation with the default monitor - just turn > > - * on, if we run a resume here, the logo disappears > > - */ > > - if (lock_fb_info(info)) { > > + /* HDMI plug in */ > > + if (!sh_hdmi_must_reconfigure(hdmi) && > > + info->state == FBINFO_STATE_RUNNING) { > > + /* > > + * First activation with the default monitor - just turn > > + * on, if we run a resume here, the logo disappears > > + */ > > info->var.width = hdmi->var.width; > > info->var.height = hdmi->var.height; > > sh_hdmi_display_on(hdmi, info); > > - unlock_fb_info(info); > > + } else { > > + /* New monitor or have to wake up */ > > + fb_set_suspend(info, 0); > > } > > - } else { > > - /* New monitor or have to wake up */ > > - fb_set_suspend(info, 0); > > - } > > > > - console_unlock(); > > + console_unlock(); > > + unlock_fb_info(info); > > + } > > } else { > > ret = 0; > > if (!hdmi->info) > > @@ -1181,12 +1181,15 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) > > fb_destroy_modedb(hdmi->monspec.modedb); > > hdmi->monspec.modedb = NULL; > > > > - console_lock(); > > + if (lock_fb_info(info)) { > > + console_lock(); > > > > - /* HDMI disconnect */ > > - fb_set_suspend(hdmi->info, 1); > > + /* HDMI disconnect */ > > + fb_set_suspend(hdmi->info, 1); > > > > - console_unlock(); > > + console_unlock(); > > + unlock_fb_info(info); > > + } > > pm_runtime_put(hdmi->dev); > > } > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c index 2b9e56a..b1a13ab 100644 --- a/drivers/video/sh_mobile_hdmi.c +++ b/drivers/video/sh_mobile_hdmi.c @@ -1151,27 +1151,27 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) ch = info->par; - console_lock(); + if (lock_fb_info(info)) { + console_lock(); - /* HDMI plug in */ - if (!sh_hdmi_must_reconfigure(hdmi) && - info->state == FBINFO_STATE_RUNNING) { - /* - * First activation with the default monitor - just turn - * on, if we run a resume here, the logo disappears - */ - if (lock_fb_info(info)) { + /* HDMI plug in */ + if (!sh_hdmi_must_reconfigure(hdmi) && + info->state == FBINFO_STATE_RUNNING) { + /* + * First activation with the default monitor - just turn + * on, if we run a resume here, the logo disappears + */ info->var.width = hdmi->var.width; info->var.height = hdmi->var.height; sh_hdmi_display_on(hdmi, info); - unlock_fb_info(info); + } else { + /* New monitor or have to wake up */ + fb_set_suspend(info, 0); } - } else { - /* New monitor or have to wake up */ - fb_set_suspend(info, 0); - } - console_unlock(); + console_unlock(); + unlock_fb_info(info); + } } else { ret = 0; if (!hdmi->info) @@ -1181,12 +1181,15 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work) fb_destroy_modedb(hdmi->monspec.modedb); hdmi->monspec.modedb = NULL; - console_lock(); + if (lock_fb_info(info)) { + console_lock(); - /* HDMI disconnect */ - fb_set_suspend(hdmi->info, 1); + /* HDMI disconnect */ + fb_set_suspend(hdmi->info, 1); - console_unlock(); + console_unlock(); + unlock_fb_info(info); + } pm_runtime_put(hdmi->dev); }