From: Javier Martinez Canillas <javierm@redhat.com> To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, Daniel Vetter <daniel.vetter@ffwll.ch>, Javier Martinez Canillas <javierm@redhat.com>, Helge Deller <deller@gmx.de>, Thomas Zimmermann <tzimmermann@suse.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org> Subject: [PATCH v5 3/7] fbdev: Restart conflicting fb removal loop when unregistering devices Date: Wed, 11 May 2022 13:30:39 +0200 [thread overview] Message-ID: <20220511113039.1252432-1-javierm@redhat.com> (raw) In-Reply-To: <20220511112438.1251024-1-javierm@redhat.com> Drivers that want to remove registered conflicting framebuffers prior to register their own framebuffer, calls remove_conflicting_framebuffers(). This function takes the registration_lock mutex, to prevent a races when drivers register framebuffer devices. But if a conflicting framebuffer device is found, the underlaying platform device is unregistered and this will lead to the platform driver .remove callback to be called, which in turn will call to the unregister_framebuffer() that takes the same lock. To prevent this, a struct fb_info.forced_out field was used as indication to unregister_framebuffer() whether the mutex has to be grabbed or not. A cleaner solution is to drop the lock before platform_device_unregister() so unregister_framebuffer() can take it when called from the fbdev driver, and just grab the lock again after the device has been registered and do a removal loop restart. Since the framebuffer devices will already be removed, the loop would just finish when no more conflicting framebuffers are found. Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- (no changes since v1) drivers/video/fbdev/core/fbmem.c | 22 +++++++++++++++------- include/linux/fb.h | 1 - 2 files changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index b445a7a00def..2fda5917c212 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1555,6 +1555,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, { int i; +restart_removal: /* check all firmware fbs and kick off if the base addr overlaps */ for_each_registered_fb(i) { struct apertures_struct *gen_aper; @@ -1587,12 +1588,23 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, pr_warn("fb%d: no device set\n", i); do_unregister_framebuffer(registered_fb[i]); } else if (dev_is_platform(device)) { - registered_fb[i]->forced_out = true; + /* + * Drop the lock because if the device is unregistered, its + * driver will call to unregister_framebuffer(), that takes + * this lock. + */ + mutex_unlock(®istration_lock); platform_device_unregister(to_platform_device(device)); + mutex_lock(®istration_lock); } else { pr_warn("fb%d: cannot remove device\n", i); do_unregister_framebuffer(registered_fb[i]); } + /* + * Restart the removal loop now that the device has been + * unregistered and its associated framebuffer gone. + */ + goto restart_removal; } } } @@ -1899,13 +1911,9 @@ EXPORT_SYMBOL(register_framebuffer); void unregister_framebuffer(struct fb_info *fb_info) { - bool forced_out = fb_info->forced_out; - - if (!forced_out) - mutex_lock(®istration_lock); + mutex_lock(®istration_lock); do_unregister_framebuffer(fb_info); - if (!forced_out) - mutex_unlock(®istration_lock); + mutex_unlock(®istration_lock); } EXPORT_SYMBOL(unregister_framebuffer); diff --git a/include/linux/fb.h b/include/linux/fb.h index 69c67c70fa78..bbe1e4571899 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -511,7 +511,6 @@ struct fb_info { } *apertures; bool skip_vt_switch; /* no VT switch on suspend/resume required */ - bool forced_out; /* set when being removed by another driver */ }; static inline struct apertures_struct *alloc_apertures(unsigned int max_num) { -- 2.35.1
WARNING: multiple messages have this Message-ID (diff)
From: Javier Martinez Canillas <javierm@redhat.com> To: linux-kernel@vger.kernel.org Cc: linux-fbdev@vger.kernel.org, Daniel Vetter <daniel.vetter@ffwll.ch>, Helge Deller <deller@gmx.de>, Javier Martinez Canillas <javierm@redhat.com>, dri-devel@lists.freedesktop.org, Thomas Zimmermann <tzimmermann@suse.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org> Subject: [PATCH v5 3/7] fbdev: Restart conflicting fb removal loop when unregistering devices Date: Wed, 11 May 2022 13:30:39 +0200 [thread overview] Message-ID: <20220511113039.1252432-1-javierm@redhat.com> (raw) In-Reply-To: <20220511112438.1251024-1-javierm@redhat.com> Drivers that want to remove registered conflicting framebuffers prior to register their own framebuffer, calls remove_conflicting_framebuffers(). This function takes the registration_lock mutex, to prevent a races when drivers register framebuffer devices. But if a conflicting framebuffer device is found, the underlaying platform device is unregistered and this will lead to the platform driver .remove callback to be called, which in turn will call to the unregister_framebuffer() that takes the same lock. To prevent this, a struct fb_info.forced_out field was used as indication to unregister_framebuffer() whether the mutex has to be grabbed or not. A cleaner solution is to drop the lock before platform_device_unregister() so unregister_framebuffer() can take it when called from the fbdev driver, and just grab the lock again after the device has been registered and do a removal loop restart. Since the framebuffer devices will already be removed, the loop would just finish when no more conflicting framebuffers are found. Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- (no changes since v1) drivers/video/fbdev/core/fbmem.c | 22 +++++++++++++++------- include/linux/fb.h | 1 - 2 files changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index b445a7a00def..2fda5917c212 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1555,6 +1555,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, { int i; +restart_removal: /* check all firmware fbs and kick off if the base addr overlaps */ for_each_registered_fb(i) { struct apertures_struct *gen_aper; @@ -1587,12 +1588,23 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, pr_warn("fb%d: no device set\n", i); do_unregister_framebuffer(registered_fb[i]); } else if (dev_is_platform(device)) { - registered_fb[i]->forced_out = true; + /* + * Drop the lock because if the device is unregistered, its + * driver will call to unregister_framebuffer(), that takes + * this lock. + */ + mutex_unlock(®istration_lock); platform_device_unregister(to_platform_device(device)); + mutex_lock(®istration_lock); } else { pr_warn("fb%d: cannot remove device\n", i); do_unregister_framebuffer(registered_fb[i]); } + /* + * Restart the removal loop now that the device has been + * unregistered and its associated framebuffer gone. + */ + goto restart_removal; } } } @@ -1899,13 +1911,9 @@ EXPORT_SYMBOL(register_framebuffer); void unregister_framebuffer(struct fb_info *fb_info) { - bool forced_out = fb_info->forced_out; - - if (!forced_out) - mutex_lock(®istration_lock); + mutex_lock(®istration_lock); do_unregister_framebuffer(fb_info); - if (!forced_out) - mutex_unlock(®istration_lock); + mutex_unlock(®istration_lock); } EXPORT_SYMBOL(unregister_framebuffer); diff --git a/include/linux/fb.h b/include/linux/fb.h index 69c67c70fa78..bbe1e4571899 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -511,7 +511,6 @@ struct fb_info { } *apertures; bool skip_vt_switch; /* no VT switch on suspend/resume required */ - bool forced_out; /* set when being removed by another driver */ }; static inline struct apertures_struct *alloc_apertures(unsigned int max_num) { -- 2.35.1
next prev parent reply other threads:[~2022-05-11 11:31 UTC|newest] Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-11 11:24 [PATCH v5 0/7] Fix some races between sysfb device registration and drivers probe Javier Martinez Canillas 2022-05-11 11:24 ` Javier Martinez Canillas 2022-05-11 11:24 ` [PATCH v5 1/7] firmware: sysfb: Make sysfb_create_simplefb() return a pdev pointer Javier Martinez Canillas 2022-05-11 11:24 ` Javier Martinez Canillas 2022-05-11 12:04 ` Javier Martinez Canillas 2022-05-11 12:04 ` Javier Martinez Canillas 2022-05-11 11:24 ` [PATCH v5 2/7] firmware: sysfb: Add helpers to unregister a pdev and disable registration Javier Martinez Canillas 2022-05-11 11:24 ` Javier Martinez Canillas 2022-05-11 11:54 ` Thomas Zimmermann 2022-05-11 11:54 ` Thomas Zimmermann 2022-05-11 12:01 ` Javier Martinez Canillas 2022-05-11 12:01 ` Javier Martinez Canillas 2022-05-11 12:05 ` Thomas Zimmermann 2022-05-11 12:05 ` Thomas Zimmermann 2022-05-11 12:29 ` Javier Martinez Canillas 2022-05-11 12:29 ` Javier Martinez Canillas 2022-05-11 12:02 ` Thomas Zimmermann 2022-05-11 12:02 ` Thomas Zimmermann 2022-05-11 12:24 ` Javier Martinez Canillas 2022-05-11 12:24 ` Javier Martinez Canillas 2022-05-11 11:30 ` Javier Martinez Canillas [this message] 2022-05-11 11:30 ` [PATCH v5 3/7] fbdev: Restart conflicting fb removal loop when unregistering devices Javier Martinez Canillas 2022-05-11 11:47 ` Thomas Zimmermann 2022-05-11 11:47 ` Thomas Zimmermann 2022-05-11 11:57 ` Javier Martinez Canillas 2022-05-11 11:57 ` Javier Martinez Canillas 2022-05-13 12:28 ` Javier Martinez Canillas 2022-05-13 12:28 ` Javier Martinez Canillas 2022-05-11 11:31 ` [PATCH v5 4/7] fbdev: Make sysfb to unregister its own registered devices Javier Martinez Canillas 2022-05-11 11:31 ` Javier Martinez Canillas 2022-05-11 11:31 ` [PATCH v5 5/7] fbdev: Disable sysfb device registration when removing conflicting FBs Javier Martinez Canillas 2022-05-11 11:31 ` Javier Martinez Canillas 2022-06-07 15:01 ` Daniel Vetter 2022-06-07 15:01 ` Daniel Vetter 2022-06-07 15:41 ` Javier Martinez Canillas 2022-05-11 11:32 ` [PATCH v5 6/7] Revert "fbdev: Prevent probing generic drivers if a FB is already registered" Javier Martinez Canillas 2022-05-11 11:32 ` Javier Martinez Canillas 2022-05-11 11:32 ` [PATCH v5 7/7] fbdev: Make registered_fb[] private to fbmem.c Javier Martinez Canillas 2022-05-11 11:32 ` Javier Martinez Canillas 2022-05-11 17:00 ` Sam Ravnborg 2022-05-11 17:00 ` Sam Ravnborg 2022-05-11 17:17 ` Guenter Roeck 2022-05-11 17:17 ` Guenter Roeck 2022-05-11 17:34 ` Javier Martinez Canillas 2022-05-11 17:34 ` Javier Martinez Canillas 2022-05-12 18:32 ` Sam Ravnborg 2022-05-12 18:32 ` Sam Ravnborg 2022-05-13 10:48 ` [PATCH v5 0/7] Fix some races between sysfb device registration and drivers probe Thomas Zimmermann 2022-05-13 10:48 ` Thomas Zimmermann 2022-05-13 11:10 ` Javier Martinez Canillas 2022-05-13 11:10 ` Javier Martinez Canillas 2022-05-13 11:32 ` Thomas Zimmermann 2022-05-13 11:32 ` Thomas Zimmermann
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