From patchwork Tue Apr 5 21:03:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12801986 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 10467C433F5 for ; Tue, 5 Apr 2022 21:04:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CD7FE10EED6; Tue, 5 Apr 2022 21:04:00 +0000 (UTC) Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7068010EEC8 for ; Tue, 5 Apr 2022 21:03:54 +0000 (UTC) Received: by mail-wr1-x435.google.com with SMTP id q19so326197wrc.6 for ; Tue, 05 Apr 2022 14:03:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=eAf6GnUNR4qzkfmM8oxrtWzw19A6DGGVW1uJzOzW25Q=; b=iRAaJ9nYq8r39GMvZWhwWGnCjiicvFhrWQUozK78cMDTl5Ovcicvhcn/I4K9GIsZsm DSFbabJ9O3KsR3OS35kqw4Zh9RDNHJryz3fL3WQAIdS4i0HkPYLa21YG/K6Sp9qjUZsr TiNk5EIAx9y0NdXxlL74P0rwLA5hS+eulSJlk= 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=eAf6GnUNR4qzkfmM8oxrtWzw19A6DGGVW1uJzOzW25Q=; b=H9XrPo1K6zG/n6MlbmVxzivhZSpGzcHG3xOKm7n4DlFwzxQ4Jls9E4GqNPoJmd86T2 QRVITi/ytkPP4nSDtX+R36M2aR4SNffhVSRpTNBSSO+o+qT2rCNoSE+9NxBvWDd7f2lA meBcBhJHHxscp4pKoTum/uT3axtaGcXFH3F1mXfWdUfbtlxm1GKxG4jun/5a2KH6rOOt 7d+f5nBtP9jdmoo2fiDkOpfYAlhFkkOKhVxMMBItfmT6JPSy3gpyw/HZwOgblxD20Psh XS04HU6CPNanjWevFQ8XbKlco1ZkFLG8nU9TWrbAHJPbKzMG9D5bBIrVnGRBrDizVh25 dE8g== X-Gm-Message-State: AOAM530lY9Ca3TJ7XBwLv/ilPlnGpX1EOLa9BLJHt4HZ3YXJJFShvFco XoxoUso6PDzo4rmeG/29eyzHrRaG/hUC4jJE1dI= X-Google-Smtp-Source: ABdhPJwZUOZ464Nx7G+r+V0R4B61UmlM8FngsriGZzYkWXARhQ5fVzXYfdItCCHo99mvdjptjEngtQ== X-Received: by 2002:a05:6000:15c3:b0:204:1185:7033 with SMTP id y3-20020a05600015c300b0020411857033mr3940754wry.625.1649192632993; Tue, 05 Apr 2022 14:03:52 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id az19-20020a05600c601300b0038cadf3aa69sm4858569wmb.36.2022.04.05.14.03.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Apr 2022 14:03:52 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH v3 12/17] fbcon: use lock_fb_info in fbcon_open/release Date: Tue, 5 Apr 2022 23:03:30 +0200 Message-Id: <20220405210335.3434130-13-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220405210335.3434130-1-daniel.vetter@ffwll.ch> References: <20220405210335.3434130-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 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: Zhen Lei , Thomas Zimmermann , Xiyu Yang , Du Cheng , Tetsuo Handa , Daniel Vetter , Intel Graphics Development , Zheyu Ma , Matthew Wilcox , William Kucharski , Claudio Suarez , Greg Kroah-Hartman , Alex Deucher , Daniel Vetter , Sam Ravnborg Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Now we get to the real motiviation, because fbmem.c insists that that's the right lock for these. Ofc fbcon.c has a lot more places where it probably should call lock_fb_info(). But looking at fbmem.c at least most of these seem to be protected by console_lock() too, which is probably what papers over any issues. Note that this means we're shuffling around a bit the locking sections for some of the console takeover and unbind paths, but not all: - console binding/unbinding from the console layer never with lock_fb_info - unbind (as opposed to unlink) never bother with lock_fb_info Also the real serialization against set_par and set_pan are still doing by wrapping the entire ioctl code in console_lock(). So this shuffling shouldn't be worse than what we had from a "can you trigger races?" pov, but it's at least clearer. Acked-by: Sam Ravnborg Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Claudio Suarez Cc: Tetsuo Handa Cc: Thomas Zimmermann Cc: Greg Kroah-Hartman Cc: Du Cheng Cc: Sam Ravnborg Cc: Matthew Wilcox Cc: William Kucharski Cc: Alex Deucher Cc: Zheyu Ma Cc: Zhen Lei Cc: Xiyu Yang --- drivers/video/fbdev/core/fbcon.c | 5 +++++ drivers/video/fbdev/core/fbmem.c | 4 ---- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index f0213a0e3870..cc960bf49991 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -684,8 +684,10 @@ static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount) static void fbcon_release(struct fb_info *info) { + lock_fb_info(info); if (info->fbops->fb_release) info->fbops->fb_release(info, 0); + unlock_fb_info(info); module_put(info->fbops->owner); } @@ -697,11 +699,14 @@ static int fbcon_open(struct fb_info *info) if (!try_module_get(info->fbops->owner)) return -ENODEV; + lock_fb_info(info); if (info->fbops->fb_open && info->fbops->fb_open(info, 0)) { + unlock_fb_info(info); module_put(info->fbops->owner); return -ENODEV; } + unlock_fb_info(info); ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL); if (!ops) { diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 34d6bb1bf82e..0e68d9456bc2 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1670,9 +1670,7 @@ static int do_register_framebuffer(struct fb_info *fb_info) console_lock(); else atomic_inc(&ignore_console_lock_warning); - lock_fb_info(fb_info); ret = fbcon_fb_registered(fb_info); - unlock_fb_info(fb_info); if (!lockless_register_fb) console_unlock(); @@ -1689,9 +1687,7 @@ static void unbind_console(struct fb_info *fb_info) return; console_lock(); - lock_fb_info(fb_info); fbcon_fb_unbind(fb_info); - unlock_fb_info(fb_info); console_unlock(); }