From patchwork Wed Apr 6 16:06:30 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: 558997 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC23CC433F5 for ; Wed, 6 Apr 2022 17:55:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239729AbiDFR5N (ORCPT ); Wed, 6 Apr 2022 13:57:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239737AbiDFR5F (ORCPT ); Wed, 6 Apr 2022 13:57:05 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B892C1A8FE8 for ; Wed, 6 Apr 2022 09:06:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649261211; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KV4A7vxPY5Ri/A7ExTRv30H1oUVvMjyO4SRhZ4A4Rkc=; b=OSyXJou27BURdMv28DN5iA0vittwcoh6uoSf5Bk8vh2qlX1EM130aDJTbMAZasgUI/nppW N0huWjp8FoV0X1pjGpd+gfJXjhMEOitKmxiaQ1ZGfn0+rHmejDbwqpTxcApwtClJT7V9lm hslKsea9zBmb7rEMRFx8dtVYIlaoH5U= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-523-TCSoDpeDOV2fl30Lek7VWw-1; Wed, 06 Apr 2022 12:06:48 -0400 X-MC-Unique: TCSoDpeDOV2fl30Lek7VWw-1 Received: by mail-wr1-f71.google.com with SMTP id j18-20020adfa552000000b002060a011303so647609wrb.14 for ; Wed, 06 Apr 2022 09:06:48 -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=KV4A7vxPY5Ri/A7ExTRv30H1oUVvMjyO4SRhZ4A4Rkc=; b=Ja3sE9U02g8KGcdbYUZOuC5HQ1fYClv0EQD8WlHLTZaUobRox/WcfhdbQYutnB0qf2 nqkr96gir+AlbyEJaXzoBi/NGyI+atn3oFhOEWTsIdRbCSFjOz2t0NX/u6ZzdkfGmd+w cUacty5Stt76JGtCBMSKX5Uvc64dULrFB9PZbC7JlG1U9JWzF9lQtD+96jlLZ7NVxPUy pka9MtdIQcgSfoYOk9HxyiJ/dpMtlPkEVkvB90dr3W5wBglSONFRx4e6CGt8MxkwaOJA 8XUXbD3z3PtQEc/+pFh1M5aXrphKs/CDPWkJx9N1e0TXqncAq232uYRWpw19n8k/Q/d+ OWIg== X-Gm-Message-State: AOAM530Bu8J8o4g7uh/SL8A3ejT72QNCX9nOhuOEBRF3dEEEAZzf/1aO JLqKzvEYBpA6XF1OVWixhUXD3BxpMQBT27GyETRib5ia02vSrGnuMaY8UaGvl1Td7Wd5yOJDWcR ZpOAn8rQ3C2Aebstwa0J2uHY= X-Received: by 2002:adf:f94d:0:b0:1e5:5ca1:2b80 with SMTP id q13-20020adff94d000000b001e55ca12b80mr7358628wrr.323.1649261207510; Wed, 06 Apr 2022 09:06:47 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx4iqTGXWAmr0kVXiSaBoH7zqLfupO6IvuwBcok5RYqdCJJH/FQ8YSgWM4GphZdzl59KrH3Wg== X-Received: by 2002:adf:f94d:0:b0:1e5:5ca1:2b80 with SMTP id q13-20020adff94d000000b001e55ca12b80mr7358600wrr.323.1649261207193; Wed, 06 Apr 2022 09:06:47 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id f1-20020a1c6a01000000b0038c9f6a3634sm5038899wmc.7.2022.04.06.09.06.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 09:06:46 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: Thomas Zimmermann , Daniel Vetter , Javier Martinez Canillas , Alex Deucher , Guenter Roeck , Helge Deller , Sam Ravnborg , Xiyu Yang , Zhen Lei , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [RFC PATCH 3/5] fbdev: Restart conflicting fb removal loop when unregistering devices Date: Wed, 6 Apr 2022 18:06:30 +0200 Message-Id: <20220406160632.496684-4-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406160632.496684-1-javierm@redhat.com> References: <20220406160632.496684-1-javierm@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org 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 --- drivers/video/fbdev/core/fbmem.c | 21 ++++++++++++++------- include/linux/fb.h | 1 - 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index b585339509b0..c1bfb8df9cba 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; @@ -1582,8 +1583,18 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * fix would add code to remove the device from the system. */ if (dev_is_platform(device)) { - registered_fb[i]->forced_out = true; + /* + * Drop the lock since the driver will call to the + * unregister_framebuffer() function that takes it. + */ + mutex_unlock(®istration_lock); platform_device_unregister(to_platform_device(device)); + mutex_lock(®istration_lock); + /* + * Restart the removal now that the platform device + * has been unregistered and its associated fb gone. + */ + goto restart_removal; } else { pr_warn("fb%d: cannot remove device\n", i); do_unregister_framebuffer(registered_fb[i]); @@ -1917,13 +1928,9 @@ 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 39baa9a70779..f1e0cd751b06 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -503,7 +503,6 @@ 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 Wed Apr 6 16:06:31 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: 558387 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65416C433F5 for ; Wed, 6 Apr 2022 17:55:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239553AbiDFR5P (ORCPT ); Wed, 6 Apr 2022 13:57:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239566AbiDFR5J (ORCPT ); Wed, 6 Apr 2022 13:57:09 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1A0971A771B for ; 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Wed, 06 Apr 2022 09:06:48 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id f1-20020a1c6a01000000b0038c9f6a3634sm5038899wmc.7.2022.04.06.09.06.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 09:06:48 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: Thomas Zimmermann , Daniel Vetter , Javier Martinez Canillas , Alex Deucher , Hans de Goede , Helge Deller , Sam Ravnborg , Xiyu Yang , Zhen Lei , Zheyu Ma , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [RFC PATCH 4/5] fbdev: Fix some race conditions between fbmem and sysfb Date: Wed, 6 Apr 2022 18:06:31 +0200 Message-Id: <20220406160632.496684-5-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406160632.496684-1-javierm@redhat.com> References: <20220406160632.496684-1-javierm@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org 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(). Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas --- drivers/video/fbdev/core/fbmem.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index c1bfb8df9cba..acf641b05d11 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 @@ -1588,7 +1589,10 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * unregister_framebuffer() function that takes it. */ mutex_unlock(®istration_lock); - platform_device_unregister(to_platform_device(device)); + if (!sysfb_try_unregister(device)) { + /* sysfb didn't register this device, unregister it */ + platform_device_unregister(to_platform_device(device)); + } mutex_lock(®istration_lock); /* * Restart the removal now that the platform device @@ -1781,6 +1785,17 @@ 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); From patchwork Wed Apr 6 16:06:32 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: 558996 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E239C433EF for ; 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Wed, 06 Apr 2022 09:06:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxjTyMg4XL89qFWV3gB2V/HQc1uQjBder3TeH9rKQDOsGox6TANK3aF+8wdzRe76EhPl9Zl5g== X-Received: by 2002:adf:dd4d:0:b0:203:f178:b78b with SMTP id u13-20020adfdd4d000000b00203f178b78bmr7137221wrm.93.1649261209641; Wed, 06 Apr 2022 09:06:49 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id f1-20020a1c6a01000000b0038c9f6a3634sm5038899wmc.7.2022.04.06.09.06.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 09:06:49 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: Thomas Zimmermann , Daniel Vetter , Zack Rusin , Javier Martinez Canillas , Hans de Goede , Ilya Trukhanov , Daniel Vetter , Peter Jones , linux-fbdev@vger.kernel.org, Helge Deller , dri-devel@lists.freedesktop.org Subject: [RFC PATCH 5/5] Revert "fbdev: Prevent probing generic drivers if a FB is already registered" Date: Wed, 6 Apr 2022 18:06:32 +0200 Message-Id: <20220406160632.496684-6-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406160632.496684-1-javierm@redhat.com> References: <20220406160632.496684-1-javierm@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org From: Daniel Vetter This reverts commit fb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee. With commit 27599aacbaefcbf2af7b06b0029459bbf682000d Author: Thomas Zimmermann Date: Tue Jan 25 10:12:18 2022 +0100 fbdev: Hot-unplug firmware fb devices on forced removal this should be fixed properly and we can remove this somewhat hackish check here (e.g. this won't catch drm drivers if fbdev emulation isn't enabled). Cc: Thomas Zimmermann Cc: Zack Rusin Cc: Javier Martinez Canillas Cc: Zack Rusin Cc: Hans de Goede Cc: Ilya Trukhanov Signed-off-by: Daniel Vetter Cc: Peter Jones Cc: linux-fbdev@vger.kernel.org Signed-off-by: Javier Martinez Canillas --- drivers/video/fbdev/efifb.c | 11 ----------- drivers/video/fbdev/simplefb.c | 11 ----------- 2 files changed, 22 deletions(-) diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index ea42ba6445b2..edca3703b964 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -351,17 +351,6 @@ static int efifb_probe(struct platform_device *dev) char *option = NULL; efi_memory_desc_t md; - /* - * Generic drivers must not be registered if a framebuffer exists. - * If a native driver was probed, the display hardware was already - * taken and attempting to use the system framebuffer is dangerous. - */ - if (num_registered_fb > 0) { - dev_err(&dev->dev, - "efifb: a framebuffer is already registered\n"); - return -EINVAL; - } - if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled) return -ENODEV; diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c index 94fc9c6d0411..0ef41173325a 100644 --- a/drivers/video/fbdev/simplefb.c +++ b/drivers/video/fbdev/simplefb.c @@ -413,17 +413,6 @@ static int simplefb_probe(struct platform_device *pdev) struct simplefb_par *par; struct resource *res, *mem; - /* - * Generic drivers must not be registered if a framebuffer exists. - * If a native driver was probed, the display hardware was already - * taken and attempting to use the system framebuffer is dangerous. - */ - if (num_registered_fb > 0) { - dev_err(&pdev->dev, - "simplefb: a framebuffer is already registered\n"); - return -EINVAL; - } - if (fb_get_options("simplefb", NULL)) return -ENODEV;