From patchwork Mon Jan 31 21:05:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12731220 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 86370C43217 for ; Mon, 31 Jan 2022 21:08:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380495AbiAaVI4 (ORCPT ); Mon, 31 Jan 2022 16:08:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380546AbiAaVHI (ORCPT ); Mon, 31 Jan 2022 16:07:08 -0500 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A38EDC061759 for ; Mon, 31 Jan 2022 13:06:53 -0800 (PST) Received: by mail-wm1-x32b.google.com with SMTP id c192so11178237wma.4 for ; Mon, 31 Jan 2022 13:06:53 -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=BL4fo+2WOVTby6QLKLV1nVWtvQ3JNOhu+8wB2s/+LIQ=; b=lLAk+I5V89CC9MFc55MMdOMjGF/tYWATRKVaKN+mU+U/Zp9rNdtcHwwA4O9ivim8U4 uhebJSd0VSHz4+CYgUEh4M7+LU+xaEJZG+163OfCeS7yOE+ftK3RBaICg7lCK+O10tNI 7MA38sqKnpewyjNRhdRuH71H/gnUy0kn0+j0I= 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=BL4fo+2WOVTby6QLKLV1nVWtvQ3JNOhu+8wB2s/+LIQ=; b=g4acAdNmvnmO1SrY96JjVVRDocamv+Lad9uf3x/aNPBHEgDqk5wrAjwdeIXUjEWrAP HpA/gxDbNdOiOunSA222bjZmwbhD5LKoKv+qlwDEPLOoaIz30cXVZf7Jgeu2WzYrMYPb kZuriVZHyf+hD6NWUzq1n7ItOMHwCUkgsgLwPZtvQmFvW65UaJTG56gYKo4LFwBJD/Zw sY2Fj9Mp7hU/gROCdh3tIKpFAVEZpKJ5TicOP4722VL7dtXHtbk/3orO71V4SnCE7ehz 4yNs7Kso3X4p/pCBwHBESVark7fuo0OkjJE2v8wx6HG36MW1EaogrxNOl/PgdNhRUtjf pUQA== X-Gm-Message-State: AOAM533tX8udQhkPlA3NpH8fBaCtVCosw5DXNpf8UWLloecHK4F/QPoc 5SDjUC7gmJ85lTeDLpiGusPa9w== X-Google-Smtp-Source: ABdhPJym9NA44EvixyMQWymA9HgMTQo3UEXCCeTnD39yMkLuzcB/0jUZ9xIYu3slC/yauz5ZL1NXmg== X-Received: by 2002:a1c:f210:: with SMTP id s16mr20179198wmc.99.1643663212301; Mon, 31 Jan 2022 13:06:52 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id b11sm314961wmq.46.2022.01.31.13.06.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jan 2022 13:06:51 -0800 (PST) From: Daniel Vetter To: DRI Development Cc: Intel Graphics Development , linux-fbdev@vger.kernel.org, LKML , Daniel Vetter , Daniel Vetter , Daniel Vetter , Tetsuo Handa , Claudio Suarez , Du Cheng , Greg Kroah-Hartman Subject: [PATCH 19/21] fbcon: Maintain a private array of fb_info Date: Mon, 31 Jan 2022 22:05:50 +0100 Message-Id: <20220131210552.482606-20-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 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Accessing the one in fbmem.c without taking the right locks is a bad idea. Instead maintain our own private copy, which is fully protected by console_lock() (like everything else in fbcon.c). That copy is serialized through fbcon_fb_registered/unregistered() calls. Also this means we do not need to hold a full fb_info reference, which is nice because doing so would mean a refcount loop between the console and the fb_info. But it's also not nice since it means console_lock() must be held absolutely everywhere. Well strictly speaking we could still try to do some refcounting games again by calling get_fb_info before we drop the console_lock. But things will get tricky. Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Tetsuo Handa Cc: Claudio Suarez Cc: Du Cheng Cc: Greg Kroah-Hartman Acked-by: Sam Ravnborg --- drivers/video/fbdev/core/fbcon.c | 82 +++++++++++++++++--------------- 1 file changed, 43 insertions(+), 39 deletions(-) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 22581952b4fd..a0ca34b29615 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -86,10 +86,6 @@ * - fbcon state itself is protected by the console_lock, and the code does a * pretty good job at making sure that lock is held everywhere it's needed. * - * - access to the registered_fb array is entirely unprotected. This should use - * proper object lifetime handling, i.e. get/put_fb_info. This also means - * switching from indices to proper pointers for fb_info everywhere. - * * - fbcon doesn't bother with fb_lock/unlock at all. This is buggy, since it * means concurrent access to the same fbdev from both fbcon and userspace * will blow up. To fix this all fbcon calls from fbmem.c need to be moved out @@ -107,6 +103,13 @@ enum { static struct fbcon_display fb_display[MAX_NR_CONSOLES]; +struct fb_info *fbcon_registered_fb[FB_MAX]; +int fbcon_num_registered_fb; + +#define fbcon_for_each_registered_fb(i) \ + for (i = 0; WARN_CONSOLE_UNLOCKED(), i < FB_MAX; i++) \ + if (!fbcon_registered_fb[i]) {} else + static signed char con2fb_map[MAX_NR_CONSOLES]; static signed char con2fb_map_boot[MAX_NR_CONSOLES]; @@ -114,12 +117,7 @@ static struct fb_info *fbcon_info_from_console(int console) { WARN_CONSOLE_UNLOCKED(); - /* - * Note that only con2fb_map is protected by the console lock, - * registered_fb is protected by a separate mutex. This lookup can - * therefore race. - */ - return registered_fb[con2fb_map[console]]; + return fbcon_registered_fb[con2fb_map[console]]; } static int logo_lines; @@ -516,7 +514,7 @@ static int do_fbcon_takeover(int show_logo) { int err, i; - if (!num_registered_fb) + if (!fbcon_num_registered_fb) return -ENODEV; if (!show_logo) @@ -822,7 +820,7 @@ static int set_con2fb_map(int unit, int newidx, int user) { struct vc_data *vc = vc_cons[unit].d; int oldidx = con2fb_map[unit]; - struct fb_info *info = registered_fb[newidx]; + struct fb_info *info = fbcon_registered_fb[newidx]; struct fb_info *oldinfo = NULL; int found, err = 0, show_logo; @@ -840,7 +838,7 @@ static int set_con2fb_map(int unit, int newidx, int user) } if (oldidx != -1) - oldinfo = registered_fb[oldidx]; + oldinfo = fbcon_registered_fb[oldidx]; found = search_fb_in_map(newidx); @@ -932,13 +930,13 @@ static const char *fbcon_startup(void) * If num_registered_fb is zero, this is a call for the dummy part. * The frame buffer devices weren't initialized yet. */ - if (!num_registered_fb || info_idx == -1) + if (!fbcon_num_registered_fb || info_idx == -1) return display_desc; /* * Instead of blindly using registered_fb[0], we use info_idx, set by * fbcon_fb_registered(); */ - info = registered_fb[info_idx]; + info = fbcon_registered_fb[info_idx]; if (!info) return NULL; @@ -1153,9 +1151,9 @@ static void fbcon_release_all(void) struct fb_info *info; int i, j, mapped; - for_each_registered_fb(i) { + fbcon_for_each_registered_fb(i) { mapped = 0; - info = registered_fb[i]; + info = fbcon_registered_fb[i]; for (j = first_fb_vc; j <= last_fb_vc; j++) { if (con2fb_map[j] == i) { @@ -1182,7 +1180,7 @@ static void fbcon_deinit(struct vc_data *vc) if (idx == -1) goto finished; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; if (!info) goto finished; @@ -2118,9 +2116,9 @@ static int fbcon_switch(struct vc_data *vc) * * info->currcon = vc->vc_num; */ - for_each_registered_fb(i) { - if (registered_fb[i]->fbcon_par) { - struct fbcon_ops *o = registered_fb[i]->fbcon_par; + fbcon_for_each_registered_fb(i) { + if (fbcon_registered_fb[i]->fbcon_par) { + struct fbcon_ops *o = fbcon_registered_fb[i]->fbcon_par; o->currcon = vc->vc_num; } @@ -2765,7 +2763,7 @@ int fbcon_mode_deleted(struct fb_info *info, j = con2fb_map[i]; if (j == -1) continue; - fb_info = registered_fb[j]; + fb_info = fbcon_registered_fb[j]; if (fb_info != info) continue; p = &fb_display[i]; @@ -2821,7 +2819,7 @@ void fbcon_fb_unbind(struct fb_info *info) set_con2fb_map(i, new_idx, 0); } } else { - struct fb_info *info = registered_fb[idx]; + struct fb_info *info = fbcon_registered_fb[idx]; /* This is sort of like set_con2fb_map, except it maps * the consoles to no device and then releases the @@ -2851,6 +2849,9 @@ void fbcon_fb_unregistered(struct fb_info *info) console_lock(); + fbcon_registered_fb[info->node] = NULL; + fbcon_num_registered_fb--; + if (deferred_takeover) { console_unlock(); return; @@ -2865,7 +2866,7 @@ void fbcon_fb_unregistered(struct fb_info *info) if (idx == info_idx) { info_idx = -1; - for_each_registered_fb(i) { + fbcon_for_each_registered_fb(i) { info_idx = i; break; } @@ -2881,7 +2882,7 @@ void fbcon_fb_unregistered(struct fb_info *info) if (primary_device == idx) primary_device = -1; - if (!num_registered_fb) + if (!fbcon_num_registered_fb) do_unregister_con_driver(&fb_con); console_unlock(); } @@ -2956,6 +2957,9 @@ int fbcon_fb_registered(struct fb_info *info) else atomic_inc(&ignore_console_lock_warning); + fbcon_registered_fb[info->node] = info; + fbcon_num_registered_fb++; + idx = info->node; fbcon_select_primary(info); @@ -3075,9 +3079,9 @@ int fbcon_set_con2fb_map_ioctl(void __user *argp) return -EINVAL; if (con2fb.framebuffer >= FB_MAX) return -EINVAL; - if (!registered_fb[con2fb.framebuffer]) + if (!fbcon_registered_fb[con2fb.framebuffer]) request_module("fb%d", con2fb.framebuffer); - if (!registered_fb[con2fb.framebuffer]) { + if (!fbcon_registered_fb[con2fb.framebuffer]) { return -EINVAL; } @@ -3144,10 +3148,10 @@ static ssize_t store_rotate(struct device *device, console_lock(); idx = con2fb_map[fg_console]; - if (idx == -1 || registered_fb[idx] == NULL) + if (idx == -1 || fbcon_registered_fb[idx] == NULL) goto err; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; rotate = simple_strtoul(buf, last, 0); fbcon_rotate(info, rotate); err: @@ -3166,10 +3170,10 @@ static ssize_t store_rotate_all(struct device *device, console_lock(); idx = con2fb_map[fg_console]; - if (idx == -1 || registered_fb[idx] == NULL) + if (idx == -1 || fbcon_registered_fb[idx] == NULL) goto err; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; rotate = simple_strtoul(buf, last, 0); fbcon_rotate_all(info, rotate); err: @@ -3186,10 +3190,10 @@ static ssize_t show_rotate(struct device *device, console_lock(); idx = con2fb_map[fg_console]; - if (idx == -1 || registered_fb[idx] == NULL) + if (idx == -1 || fbcon_registered_fb[idx] == NULL) goto err; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; rotate = fbcon_get_rotate(info); err: console_unlock(); @@ -3206,10 +3210,10 @@ static ssize_t show_cursor_blink(struct device *device, console_lock(); idx = con2fb_map[fg_console]; - if (idx == -1 || registered_fb[idx] == NULL) + if (idx == -1 || fbcon_registered_fb[idx] == NULL) goto err; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; ops = info->fbcon_par; if (!ops) @@ -3232,10 +3236,10 @@ static ssize_t store_cursor_blink(struct device *device, console_lock(); idx = con2fb_map[fg_console]; - if (idx == -1 || registered_fb[idx] == NULL) + if (idx == -1 || fbcon_registered_fb[idx] == NULL) goto err; - info = registered_fb[idx]; + info = fbcon_registered_fb[idx]; if (!info->fbcon_par) goto err; @@ -3295,8 +3299,8 @@ static void fbcon_register_existing_fbs(struct work_struct *work) deferred_takeover = false; logo_shown = FBCON_LOGO_DONTSHOW; - for_each_registered_fb(i) - fbcon_fb_registered(registered_fb[i]); + fbcon_for_each_registered_fb(i) + fbcon_fb_registered(fbcon_registered_fb[i]); console_unlock(); }