From patchwork Mon Jan 31 21:05:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12731178 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 E573DC433FE for ; Mon, 31 Jan 2022 21:07:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3276A10E537; Mon, 31 Jan 2022 21:06:52 +0000 (UTC) Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by gabe.freedesktop.org (Postfix) with ESMTPS id 451EB10E50C for ; Mon, 31 Jan 2022 21:06:49 +0000 (UTC) Received: by mail-wm1-x332.google.com with SMTP id n8so11190413wmk.3 for ; Mon, 31 Jan 2022 13:06:49 -0800 (PST) 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=3hWiJw8I0v/FhKndgqc2O30e2FmZYwhYniGtWb90tWY=; b=HHQSy572JqEYwMH+XAImxbYANsnDK/FocLe1VGb5+1HoyTQOlf6pkJdzMLp+bQVtjl 6nGB7Yu3HDEDy7AAoG4b1oLVSDRpa9s5ddsKnU8r6m1P82LiOt+SAZcWqZYeQWPQARgU WXr3wNTQE3KehfvQbrgyI6k9xn3+ZGRP2IBiM= 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=3hWiJw8I0v/FhKndgqc2O30e2FmZYwhYniGtWb90tWY=; b=6ExaHpxAvqavnQii+G3GiaqO1J9/quRBKxrHFgnC9apB3CmqugBdjRpYHBpp/0JbNE 2xbYRGBFWAkjZPZKySKnm3IHRg38JUY2Lnl/mF+XoxlYecIqhekYJaBFLLnbi56+1jvY uIbM+fbxBTdwc5uZ7xq49g6hqrtMyXDXulj7NsBI5iS9o3VzcVF08ObhOPCTDmb/L3qM Rm+WHqYUgJQamE1HBmC8bCki5XTdhECiL8UDipBgngcKHOb2mkffoQ+vLrQ7Sd0f75qv GnMCnGbCtxEmo43yXFbzhj5m35Pzk/YwD4qjoEGEHQ1IexvBhz77vPAr2ABXUAP/DRm4 od6w== X-Gm-Message-State: AOAM532gCYOCk0qMGpr/Itao4UGDVxuovM0SSqUzjV+dq5hP2/KQsOah ZPJ8yRCSr1usn80XcSmmH2JO1w== X-Google-Smtp-Source: ABdhPJxUkcP7tvQC/1g/mrtlDB25tdXfgU7PSiuLoapLSdk12hfg/ro1vp1kr0Y7TNymzUpLM79pKg== X-Received: by 2002:a7b:c4c5:: with SMTP id g5mr19646400wmk.139.1643663207885; Mon, 31 Jan 2022 13:06:47 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id b11sm314961wmq.46.2022.01.31.13.06.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jan 2022 13:06:47 -0800 (PST) From: Daniel Vetter To: DRI Development Date: Mon, 31 Jan 2022 22:05:45 +0100 Message-Id: <20220131210552.482606-15-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20220131210552.482606-1-daniel.vetter@ffwll.ch> References: <20220131210552.482606-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 14/21] fbcon: use lock_fb_info in fbcon_open/release X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fbdev@vger.kernel.org, Thomas Zimmermann , Xiyu Yang , Du Cheng , Tetsuo Handa , Daniel Vetter , Intel Graphics Development , Zheyu Ma , LKML , Matthew Wilcox , William Kucharski , Greg Kroah-Hartman , Alex Deucher , Daniel Vetter , Sam Ravnborg , Zhen Lei Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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. 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 Acked-by: Sam Ravnborg --- 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 5a3391ff038d..496bc5f2133e 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -682,8 +682,10 @@ 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); } @@ -695,11 +697,14 @@ 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 0fa7ede94fa6..fd51d12f2702 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1653,9 +1653,7 @@ 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(); @@ -1672,9 +1670,7 @@ 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(); }