From patchwork Tue Apr 5 21:03:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12801987 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 44B93C433EF for ; Tue, 5 Apr 2022 21:04:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0BE2910EED8; Tue, 5 Apr 2022 21:04:01 +0000 (UTC) Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9D20810EED6 for ; Tue, 5 Apr 2022 21:03:59 +0000 (UTC) Received: by mail-wm1-x331.google.com with SMTP id v64-20020a1cac43000000b0038cfd1b3a6dso2391146wme.5 for ; Tue, 05 Apr 2022 14:03:59 -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=NyPCuPft4VaB2bVEt8jlMDRi9/YFFe0dNdOhzBh/pVo=; b=F0HQJ24i4ks7yQx5hR3xUHdrEk++vfZB+I6vxXQIZ+gvJZb71cJIpwJkGuTE1qxUY8 dPfReQUnyZlr1Jx02A211gFq6p0RYy9c5WgrtTY5l9rW+cswOGal9TwuZ6+wl2H0ZMmY pgcmJBcaquPgl7T0boc+KUa/i2PCVRlv+qiVM= 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=NyPCuPft4VaB2bVEt8jlMDRi9/YFFe0dNdOhzBh/pVo=; b=jDosedpkMFL5PrJH+1I5k6zYtzSbelYJiY5coJeQh7JXIbSi4wcqGjg0EEfID5SOz1 AxvcMWR7zt7O5RKGTOdb4B+eH+A7ksLkhmT7AqEENjEsJY7MkwRqSuiceoSupwLgCPad y2oBIkWDA5RySi6/9APrEFRKhZMV8afXteyuUPwOl1WnqoM8P0XQuINmVU1IxNOhdDiL UO6hOPdd3uWaKhrgr59rZYCe9tPW8eJlgjzXCSIFOgWayms1LJmUFS04rA1n/Dy2o3HW JkUGmbQkx36HV+WW5rtWPJ4GrRbBPaDgtxe2pJfOgleFWSaCsHQe6Dkyk7JCc0Y6aKl4 e5uA== X-Gm-Message-State: AOAM532f7NL5yXslvswzjnw4hEe+iHFlf6nqZuVlB0ypVVjI1rguO6N8 OezOAC3HqAlLBtM6kTM6TqID0dHcBVAiwBeH1Lg= X-Google-Smtp-Source: ABdhPJy5CEDzX/GSZ9PpOzupBU5FccZ6aBQUJQDtPxDsf166S1k20pgXiSnB2gHxdDGFN399cLXKKQ== X-Received: by 2002:a05:600c:3d0e:b0:38c:9b5e:52c0 with SMTP id bh14-20020a05600c3d0e00b0038c9b5e52c0mr4509016wmb.3.1649192638129; Tue, 05 Apr 2022 14:03:58 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id az19-20020a05600c601300b0038cadf3aa69sm4858569wmb.36.2022.04.05.14.03.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Apr 2022 14:03:57 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH v3 17/17] fbcon: Maintain a private array of fb_info Date: Tue, 5 Apr 2022 23:03:35 +0200 Message-Id: <20220405210335.3434130-18-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: Du Cheng , Tetsuo Handa , Daniel Vetter , Intel Graphics Development , Claudio Suarez , Greg Kroah-Hartman , Daniel Vetter , Sam Ravnborg Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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. Acked-by: Sam Ravnborg Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Tetsuo Handa Cc: Claudio Suarez Cc: Du Cheng Cc: Greg Kroah-Hartman --- 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 944f514c77ec..6a7d470beec7 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; @@ -518,7 +516,7 @@ 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) @@ -821,7 +819,7 @@ 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; @@ -839,7 +837,7 @@ 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); @@ -931,13 +929,13 @@ 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; @@ -1150,9 +1148,9 @@ 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) { @@ -1179,7 +1177,7 @@ 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; @@ -2098,9 +2096,9 @@ 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; } @@ -2745,7 +2743,7 @@ 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]; @@ -2801,7 +2799,7 @@ 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 @@ -2831,6 +2829,9 @@ 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; @@ -2845,7 +2846,7 @@ 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; } @@ -2861,7 +2862,7 @@ 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(); } @@ -2936,6 +2937,9 @@ 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); @@ -3055,9 +3059,9 @@ 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; } @@ -3124,10 +3128,10 @@ 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: @@ -3146,10 +3150,10 @@ 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: @@ -3166,10 +3170,10 @@ 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(); @@ -3186,10 +3190,10 @@ 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) @@ -3212,10 +3216,10 @@ 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; @@ -3275,8 +3279,8 @@ 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(); }