From patchwork Fri Apr 8 16:13:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 12806926 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D72AEC4167B for ; Fri, 8 Apr 2022 16:13:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3B0E310E4E4; Fri, 8 Apr 2022 16:13:47 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 286C710E491 for ; Fri, 8 Apr 2022 16:13:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649434425; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=siz3X/UqDfw+7svtYWKLABxX78u03m0eRqZg4+H+2FU=; b=UmbPeNqXTaT/Akn9Co5nwxlVsrq/efbUnVF0sXZB2Bq+Mf/JbN0VUqSMqIdxvieneAWjL5 0m9RDZVGM48lVi3h8trcDgIOnLpMGgekEsBv9KPRsG4OeBKXURuHVqdIiJZ/J8Pzy1mX8Z NhfbpdVrv5Z7KUfQpfuEw0oB4pCBpKA= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-632-c9azeqd6M6i5j11xo8E3Ng-1; Fri, 08 Apr 2022 12:13:42 -0400 X-MC-Unique: c9azeqd6M6i5j11xo8E3Ng-1 Received: by mail-wm1-f69.google.com with SMTP id l4-20020a05600c1d0400b0038eaa928a67so567294wms.7 for ; Fri, 08 Apr 2022 09:13:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=siz3X/UqDfw+7svtYWKLABxX78u03m0eRqZg4+H+2FU=; b=4tcEjAe1vgqeO1AxKE9QSV4GtTmG6v6Dos2e2kKjw0onE/M9YfhdEzrvNIbPFldDLU UH+mUZL7SF6Yx8XrnS5zi01CkEVQi5GLYJdf//ZGpQ2TB2wyNyazxklKxYWhSVLR8eTO pVj1V9qjGaKD6LVs9WcS1r1BHx1rGgWdo+r5QkN5bWxpJRVraZT0y0+Z9zu4+5Y/aKvI r5VvaoMJ8pzUwRXiOjvpWnvy7JmdxrGh5/uYibu880++5LOLJJrKknHdSAEjoTJr8wxg h8cMgZh2pV1kmapf7IVW1x3BozPTG9tGykxEpUnzxesm2DxnxoskFec5IoHujv27pR+d 1mrg== X-Gm-Message-State: AOAM530MBxRSkLJh/QpbOPJl05ZKHc8c2QYUIh2Vx+Yo1PNNeXTF98M4 p/4KZttRLIJDtSNHxCPEHHWfM7UFI6gm+PfK9hWlViv43lUeuq8oA7TPpTPD7xl0BL3Ol3nCWDH DpVD0R6f2CfK4Pr+SDBwCGnwL27+b X-Received: by 2002:a7b:cc12:0:b0:37c:1ae:100a with SMTP id f18-20020a7bcc12000000b0037c01ae100amr17200080wmh.54.1649434420846; Fri, 08 Apr 2022 09:13:40 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwq9i7g5A8Qdq92aXqmOvWOWToxcYSKRxuzMjwX82CkOUOdA+5yc/tgzh001RXjv6GYYOhx5Q== X-Received: by 2002:a7b:cc12:0:b0:37c:1ae:100a with SMTP id f18-20020a7bcc12000000b0037c01ae100amr17200054wmh.54.1649434420622; Fri, 08 Apr 2022 09:13:40 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id t15-20020adfeb8f000000b002060d26c211sm14377455wrn.114.2022.04.08.09.13.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Apr 2022 09:13:40 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Subject: [PATCH v2 1/5] firmware: sysfb: Make sysfb_create_simplefb() return a pdev pointer Date: Fri, 8 Apr 2022 18:13:18 +0200 Message-Id: <20220408161322.270176-2-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220408161322.270176-1-javierm@redhat.com> References: <20220408161322.270176-1-javierm@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=javierm@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Miaoqian Lin , Greg Kroah-Hartman , Javier Martinez Canillas , dri-devel@lists.freedesktop.org, Johan Hovold , Thomas Zimmermann , Daniel Vetter , Borislav Petkov Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This function just returned 0 on success or an errno code on error, but it could be useful for sysfb_init() callers to have a pointer to the device. Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- Changes in v2: - Rebase on top of latest drm-misc-next and fix conflicts (Daniel Vetter). drivers/firmware/sysfb.c | 4 ++-- drivers/firmware/sysfb_simplefb.c | 16 ++++++++-------- include/linux/sysfb.h | 10 +++++----- 3 files changed, 15 insertions(+), 15 deletions(-) diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c index 2bfbb05f7d89..b032f40a92de 100644 --- a/drivers/firmware/sysfb.c +++ b/drivers/firmware/sysfb.c @@ -46,8 +46,8 @@ static __init int sysfb_init(void) /* try to create a simple-framebuffer device */ compatible = sysfb_parse_mode(si, &mode); if (compatible) { - ret = sysfb_create_simplefb(si, &mode); - if (!ret) + pd = sysfb_create_simplefb(si, &mode); + if (!IS_ERR(pd)) return 0; } diff --git a/drivers/firmware/sysfb_simplefb.c b/drivers/firmware/sysfb_simplefb.c index bda8712bfd8c..a353e27f83f5 100644 --- a/drivers/firmware/sysfb_simplefb.c +++ b/drivers/firmware/sysfb_simplefb.c @@ -57,8 +57,8 @@ __init bool sysfb_parse_mode(const struct screen_info *si, return false; } -__init int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode) +__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si, + const struct simplefb_platform_data *mode) { struct platform_device *pd; struct resource res; @@ -76,7 +76,7 @@ __init int sysfb_create_simplefb(const struct screen_info *si, base |= (u64)si->ext_lfb_base << 32; if (!base || (u64)(resource_size_t)base != base) { printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n"); - return -EINVAL; + return ERR_PTR(-EINVAL); } /* @@ -93,7 +93,7 @@ __init int sysfb_create_simplefb(const struct screen_info *si, length = mode->height * mode->stride; if (length > size) { printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n"); - return -EINVAL; + return ERR_PTR(-EINVAL); } length = PAGE_ALIGN(length); @@ -104,11 +104,11 @@ __init int sysfb_create_simplefb(const struct screen_info *si, res.start = base; res.end = res.start + length - 1; if (res.end <= res.start) - return -EINVAL; + return ERR_PTR(-EINVAL); pd = platform_device_alloc("simple-framebuffer", 0); if (!pd) - return -ENOMEM; + return ERR_PTR(-ENOMEM); sysfb_apply_efi_quirks(pd); @@ -124,10 +124,10 @@ __init int sysfb_create_simplefb(const struct screen_info *si, if (ret) goto err_put_device; - return 0; + return pd; err_put_device: platform_device_put(pd); - return ret; + return ERR_PTR(ret); } diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h index b0dcfa26d07b..708152e9037b 100644 --- a/include/linux/sysfb.h +++ b/include/linux/sysfb.h @@ -72,8 +72,8 @@ static inline void sysfb_apply_efi_quirks(struct platform_device *pd) bool sysfb_parse_mode(const struct screen_info *si, struct simplefb_platform_data *mode); -int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode); +struct platform_device *sysfb_create_simplefb(const struct screen_info *si, + const struct simplefb_platform_data *mode); #else /* CONFIG_SYSFB_SIMPLE */ @@ -83,10 +83,10 @@ static inline bool sysfb_parse_mode(const struct screen_info *si, return false; } -static inline int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode) +static inline struct platform_device *sysfb_create_simplefb(const struct screen_info *si, + const struct simplefb_platform_data *mode) { - return -EINVAL; + return ERR_PTR(-EINVAL); } #endif /* CONFIG_SYSFB_SIMPLE */ From patchwork Fri Apr 8 16:13:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 12806925 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C80A0C433FE for ; Fri, 8 Apr 2022 16:13:50 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6BEFC10E4C0; 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Fri, 08 Apr 2022 09:13:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyb1bR0lxJrypE9QzahDsl2bHOBw/ximpksO0RRlntgb9gNAXEXCpGe5WPVpBzMKq9R/nVknw== X-Received: by 2002:a05:600c:3ba5:b0:38c:b19e:253c with SMTP id n37-20020a05600c3ba500b0038cb19e253cmr17515110wms.35.1649434421957; Fri, 08 Apr 2022 09:13:41 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id t15-20020adfeb8f000000b002060d26c211sm14377455wrn.114.2022.04.08.09.13.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Apr 2022 09:13:41 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Subject: [PATCH v2 2/5] firmware: sysfb: Add helpers to unregister a pdev and disable registration Date: Fri, 8 Apr 2022 18:13:19 +0200 Message-Id: <20220408161322.270176-3-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220408161322.270176-1-javierm@redhat.com> References: <20220408161322.270176-1-javierm@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=javierm@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jonathan Corbet , Greg Kroah-Hartman , linux-doc@vger.kernel.org, Javier Martinez Canillas , dri-devel@lists.freedesktop.org, Thomas Zimmermann , Daniel Vetter , Borislav Petkov Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" These can be used by subsystems to unregister a platform device registered by sysfb and also to disable future platform device registration in sysfb. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- Changes in v2: - Add kernel-doc comments and include in other_interfaces.rst (Daniel Vetter). .../driver-api/firmware/other_interfaces.rst | 6 ++ drivers/firmware/sysfb.c | 73 +++++++++++++++++-- include/linux/sysfb.h | 19 +++++ 3 files changed, 92 insertions(+), 6 deletions(-) diff --git a/Documentation/driver-api/firmware/other_interfaces.rst b/Documentation/driver-api/firmware/other_interfaces.rst index b81794e0cfbb..06ac89adaafb 100644 --- a/Documentation/driver-api/firmware/other_interfaces.rst +++ b/Documentation/driver-api/firmware/other_interfaces.rst @@ -13,6 +13,12 @@ EDD Interfaces .. kernel-doc:: drivers/firmware/edd.c :internal: +Generic System Framebuffers Interface +------------------------------------- + +.. kernel-doc:: drivers/firmware/sysfb.c + :export: + Intel Stratix10 SoC Service Layer --------------------------------- Some features of the Intel Stratix10 SoC require a level of privilege diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c index b032f40a92de..a50d2858ce4d 100644 --- a/drivers/firmware/sysfb.c +++ b/drivers/firmware/sysfb.c @@ -34,21 +34,78 @@ #include #include +static struct platform_device *pd; +static DEFINE_MUTEX(load_lock); +static bool disabled; + +/** + * sysfb_disable() - disable the Generic System Framebuffers support + * + * This disables the registration of system framebuffer devices that match the + * generic drivers that make use of the system framebuffer set up by firmware. + * + * Context: The function can sleep. A @load_lock mutex is acquired to serialize + * against sysfb_init(), that registers a system framebuffer device and + * sysfb_try_unregister(), that tries to unregister framebuffer devices. + */ +void sysfb_disable(void) +{ + mutex_lock(&load_lock); + disabled = true; + mutex_unlock(&load_lock); +} +EXPORT_SYMBOL_GPL(sysfb_disable); + +/** + * sysfb_try_unregister() - attempt to unregister a system framebuffer device + * @dev: device to unregister + * + * This tries to unregister a system framebuffer device if this was registered + * by the Generic System Framebuffers. The device will only be unregistered if + * it was registered by sysfb_init(), otherwise it will not be unregistered. + * + * Context: The function can sleep. a @load_lock mutex is acquired to serialize + * against sysfb_init(), that registers a simple framebuffer device and + * sysfb_disable(), that disables the Generic System Framebuffers support. + * + * Return: + * * true - the device was unregistered successfully + * * false - the device was not unregistered + */ +bool sysfb_try_unregister(struct device *dev) +{ + bool ret = true; + + mutex_lock(&load_lock); + if (!pd || pd != to_platform_device(dev)) + return false; + + platform_device_unregister(to_platform_device(dev)); + pd = NULL; + mutex_unlock(&load_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(sysfb_try_unregister); + static __init int sysfb_init(void) { struct screen_info *si = &screen_info; struct simplefb_platform_data mode; - struct platform_device *pd; const char *name; bool compatible; - int ret; + int ret = 0; + + mutex_lock(&load_lock); + if (disabled) + goto unlock_mutex; /* try to create a simple-framebuffer device */ compatible = sysfb_parse_mode(si, &mode); if (compatible) { pd = sysfb_create_simplefb(si, &mode); if (!IS_ERR(pd)) - return 0; + goto unlock_mutex; } /* if the FB is incompatible, create a legacy framebuffer device */ @@ -60,8 +117,10 @@ static __init int sysfb_init(void) name = "platform-framebuffer"; pd = platform_device_alloc(name, 0); - if (!pd) - return -ENOMEM; + if (!pd) { + ret = -ENOMEM; + goto unlock_mutex; + } sysfb_apply_efi_quirks(pd); @@ -73,9 +132,11 @@ static __init int sysfb_init(void) if (ret) goto err; - return 0; + goto unlock_mutex; err: platform_device_put(pd); +unlock_mutex: + mutex_unlock(&load_lock); return ret; } diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h index 708152e9037b..e8c0313fac8f 100644 --- a/include/linux/sysfb.h +++ b/include/linux/sysfb.h @@ -55,6 +55,25 @@ struct efifb_dmi_info { int flags; }; +#ifdef CONFIG_SYSFB + +void sysfb_disable(void); +bool sysfb_try_unregister(struct device *dev); + +#else /* CONFIG_SYSFB */ + +static inline void sysfb_disable(void) +{ + +} + +static inline bool sysfb_try_unregister(struct device *dev) +{ + return false; +} + +#endif /* CONFIG_SYSFB */ + #ifdef CONFIG_EFI extern struct efifb_dmi_info efifb_dmi_list[]; From patchwork Fri Apr 8 16:13:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 12806927 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 722EEC433EF for ; Fri, 8 Apr 2022 16:13:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8074710E4ED; Fri, 8 Apr 2022 16:13:48 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id D725110E491 for ; 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Fri, 08 Apr 2022 09:13:43 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id t15-20020adfeb8f000000b002060d26c211sm14377455wrn.114.2022.04.08.09.13.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Apr 2022 09:13:43 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Subject: [PATCH v2 3/5] fbdev: Restart conflicting fb removal loop when unregistering devices Date: Fri, 8 Apr 2022 18:13:20 +0200 Message-Id: <20220408161322.270176-4-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220408161322.270176-1-javierm@redhat.com> References: <20220408161322.270176-1-javierm@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=javierm@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fbdev@vger.kernel.org, Tetsuo Handa , Greg Kroah-Hartman , Helge Deller , Zhen Lei , Javier Martinez Canillas , dri-devel@lists.freedesktop.org, Changcheng Deng , Thomas Zimmermann , Daniel Vetter , Alex Deucher , Sam Ravnborg , Guenter Roeck Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- (no changes since v1) drivers/video/fbdev/core/fbmem.c | 29 +++++++++++++++++++---------- include/linux/fb.h | 1 - 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index bdd00d381bbc..bcdbbe543466 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1553,6 +1553,7 @@ 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; @@ -1576,16 +1577,28 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * VESA, EFI, etc. A native driver will then be able to * allocate the memory range. * - * If it's not a platform device, at least print a warning. A - * fix would add code to remove the device from the system. + * Drop the lock because if the device is unregistered, its + * drivers will call to unregister_framebuffer() that takes + * this lock. */ + mutex_unlock(®istration_lock); if (dev_is_platform(device)) { - registered_fb[i]->forced_out = true; platform_device_unregister(to_platform_device(device)); } else { + /* + * If it's not a platform device, at least print a warning. A + * fix would add to code to remove the device from the system. + */ pr_warn("fb%d: cannot remove device\n", i); - do_unregister_framebuffer(registered_fb[i]); + /* call unregister_framebuffer() so it can take the lock */ + unregister_framebuffer(registered_fb[i]); } + mutex_lock(®istration_lock); + /* + * Restart the removal loop now that the device has been + * unregistered and its associated framebuffer gone. + */ + goto restart_removal; } } } @@ -1892,13 +1905,9 @@ 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 f95da1af9ff6..b781bc721113 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -502,7 +502,6 @@ 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) { From patchwork Fri Apr 8 16:13:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 12806928 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7B0DDC433F5 for ; Fri, 8 Apr 2022 16:13:58 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9BAC610E491; Fri, 8 Apr 2022 16:13:53 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id E213610E4F6 for ; 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Fri, 08 Apr 2022 09:13:45 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id t15-20020adfeb8f000000b002060d26c211sm14377455wrn.114.2022.04.08.09.13.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Apr 2022 09:13:45 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Subject: [PATCH v2 4/5] fbdev: Fix some race conditions between fbmem and sysfb Date: Fri, 8 Apr 2022 18:13:21 +0200 Message-Id: <20220408161322.270176-5-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220408161322.270176-1-javierm@redhat.com> References: <20220408161322.270176-1-javierm@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=javierm@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fbdev@vger.kernel.org, Xiyu Yang , Greg Kroah-Hartman , Helge Deller , Zhen Lei , Javier Martinez Canillas , dri-devel@lists.freedesktop.org, Changcheng Deng , Thomas Zimmermann , Daniel Vetter , Alex Deucher , Sam Ravnborg , Guenter Roeck Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The platform devices registered in sysfb match with a firmware-based fbdev or DRM driver, that are used to have early graphics using framebuffers set up by the system firmware. Real DRM drivers later are probed and remove all conflicting framebuffers, leading to these platform devices for generic drivers to be unregistered. But the current solution has two issues that this patch fixes: 1) It is a layering violation for the fbdev core to unregister a device that was registered by sysfb. Instead, the sysfb_try_unregister() helper function can be called for sysfb to attempt unregistering the device if is the one registered. 2) The sysfb_init() function could be called after a DRM driver is probed and requested to unregister devices for drivers with a conflicting fb. To prevent this, disable any future sysfb platform device registration by calling sysfb_disable(), if a driver requested to remove conflicting framebuffers with remove_conflicting_framebuffers(). There are video drivers (e.g: vga16fb) that register their own device and don't use the sysfb infrastructure for that, so an unregistration has to be forced by fbmem if sysfb_try_unregister() fails to do the unregister. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- Changes in v2: - Explain in the commit message that fbmem has to unregister the device as fallback if a driver registered the device itself (Daniel Vetter). - Also explain that fallback in a comment in the code (Daniel Vetter). - Don't encode in fbmem the assumption that sysfb will always register platform devices (Daniel Vetter). - Add a FIXME comment about drivers registering devices (Daniel Vetter). drivers/video/fbdev/core/fbmem.c | 42 +++++++++++++++++++++++--------- 1 file changed, 31 insertions(+), 11 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index bcdbbe543466..6cb73193410e 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -1582,22 +1583,30 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * this lock. */ mutex_unlock(®istration_lock); - if (dev_is_platform(device)) { - platform_device_unregister(to_platform_device(device)); - } else { - /* - * If it's not a platform device, at least print a warning. A - * fix would add to code to remove the device from the system. - */ - pr_warn("fb%d: cannot remove device\n", i); - /* call unregister_framebuffer() so it can take the lock */ - unregister_framebuffer(registered_fb[i]); + if (!sysfb_try_unregister(device)) { + if (dev_is_platform(device)) { + /* + * FIXME: sysfb didn't register this device, is a platform + * device registered by a video driver (e.g: vga16fb), so + * force its unregistration here. A proper fix would be to + * move all device registration to the sysfb infrastructure. + */ + platform_device_unregister(to_platform_device(device)); + } else { + /* + * If it's not a platform device, at least print a warning. A + * fix would add to code to remove the device from the system. + */ + pr_warn("fb%d: cannot remove device\n", i); + /* call unregister_framebuffer() so it can take the lock */ + unregister_framebuffer(registered_fb[i]); + } } - mutex_lock(®istration_lock); /* * Restart the removal loop now that the device has been * unregistered and its associated framebuffer gone. */ + mutex_lock(®istration_lock); goto restart_removal; } } @@ -1758,6 +1767,17 @@ int remove_conflicting_framebuffers(struct apertures_struct *a, do_free = true; } + /* + * If a driver asked to unregister a platform device registered by + * sysfb, then can be assumed that this is a driver for a display + * that is set up by the system firmware and has a generic driver. + * + * Drivers for devices that don't have a generic driver will never + * ask for this, so let's assume that a real driver for the display + * was already probed and prevent sysfb to register devices later. + */ + sysfb_disable(); + mutex_lock(®istration_lock); do_remove_conflicting_framebuffers(a, name, primary); mutex_unlock(®istration_lock);