From patchwork Mon May 6 18:01:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Noralf_Tr=C3=B8nnes?= X-Patchwork-Id: 10931743 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EA29B933 for ; Mon, 6 May 2019 18:02:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D8C802884B for ; Mon, 6 May 2019 18:02:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CD0D328864; Mon, 6 May 2019 18:02:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 3C58B2884B for ; Mon, 6 May 2019 18:02:22 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 04E1389B83; Mon, 6 May 2019 18:02:12 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from smtp.domeneshop.no (smtp.domeneshop.no [IPv6:2a01:5b40:0:3005::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1E07989B65; Mon, 6 May 2019 18:02:10 +0000 (UTC) Received: from 211.81-166-168.customer.lyse.net ([81.166.168.211]:52392 helo=localhost.localdomain) by smtp.domeneshop.no with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.84_2) (envelope-from ) id 1hNhwG-0007OJ-Ag; Mon, 06 May 2019 20:02:08 +0200 From: =?utf-8?q?Noralf_Tr=C3=B8nnes?= To: dri-devel@lists.freedesktop.org Subject: [PATCH v5 02/11] drm/fb-helper: Avoid race with DRM userspace Date: Mon, 6 May 2019 20:01:30 +0200 Message-Id: <20190506180139.6913-3-noralf@tronnes.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190506180139.6913-1-noralf@tronnes.org> References: <20190506180139.6913-1-noralf@tronnes.org> MIME-Version: 1.0 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tronnes.org; s=ds201810; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=MxHEYCJB1V9ekXPqBEyc/RpO8a7QBKfStO6l964aq80=; b=Ag1VxCllTVFp6gVC+GhdcME+wqH5qSlcnRaJW5icvJL+dWyEjk5IaTS7N5ZMQKFVrGwFMjPhkUT67HGtpYcXyRwhwHRHppfaIiQTSg+xrj8B0zPhrobkaXr9ndkGS4YOUICQxtd9z9Ok4h9sNU2SDhVhhHOy02fYHcMNklFAMmsYZXMTNyESlhOf1J5LVG3lv0lPgNPjIka0Iu+DL3SZkZDCPir238MH1WNIaj9Jz27/6ekVbctfFQaozwHmJI6U5z//dL3ZE2Y6hcq8UpGR8jdrq99sfI72jLniq8M09FHPHU0hFw/V8ek2qQyMe8gQUA0ETg7qvlWZVhhYFC3ZPA==; X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP drm_fb_helper_is_bound() is used to check if DRM userspace is in control. This is done by looking at the fb on the primary plane. By the time fb-helper gets around to committing, it's possible that the facts have changed. Avoid this race by holding the drm_device->master_mutex lock while committing. When DRM userspace does its first open, it will now wait until fb-helper is done. The helper will stay away if there's a master. Two igt tests fail with the new 'bail out if master' rule. Work around this by relaxing this rule for drm_fb_helper_restore_fbdev_mode_unlocked() until the tests have been fixed. Add todo entry for this. Locking rule: Always take the fb-helper lock first. v5: drm_fb_helper_restore_fbdev_mode_unlocked(): Use restore_fbdev_mode_force() v2: - Remove drm_fb_helper_is_bound() (Daniel Vetter) - No need to check fb_helper->dev->master in drm_fb_helper_single_fb_probe(), restore_fbdev_mode() has the check. Suggested-by: Daniel Vetter Signed-off-by: Noralf Trønnes Reviewed-by: Daniel Vetter --- Documentation/gpu/todo.rst | 8 +++ drivers/gpu/drm/drm_auth.c | 20 +++++++ drivers/gpu/drm/drm_fb_helper.c | 102 ++++++++++++++++++-------------- drivers/gpu/drm/drm_internal.h | 2 + 4 files changed, 86 insertions(+), 46 deletions(-) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 06ccff9165d5..66f05f4e469f 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -281,6 +281,14 @@ it to use drm_mode_hsync() instead. Contact: Sean Paul +drm_fb_helper tasks +------------------- + +- drm_fb_helper_restore_fbdev_mode_unlocked() should call restore_fbdev_mode() + not the _force variant so it can bail out if there is a master. But first + these igt tests need to be fixed: kms_fbcon_fbt@psr and + kms_fbcon_fbt@psr-suspend. + Core refactorings ================= diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index e88151b65c22..33aa459a1b8f 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -353,3 +353,23 @@ void drm_master_put(struct drm_master **master) *master = NULL; } EXPORT_SYMBOL(drm_master_put); + +/* Used by drm_client and drm_fb_helper */ +bool drm_master_internal_acquire(struct drm_device *dev) +{ + mutex_lock(&dev->master_mutex); + if (dev->master) { + mutex_unlock(&dev->master_mutex); + return false; + } + + return true; +} +EXPORT_SYMBOL(drm_master_internal_acquire); + +/* Used by drm_client and drm_fb_helper */ +void drm_master_internal_release(struct drm_device *dev) +{ + mutex_unlock(&dev->master_mutex); +} +EXPORT_SYMBOL(drm_master_internal_release); diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 45c5128a783b..6b4ce6060984 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -44,6 +44,7 @@ #include "drm_crtc_internal.h" #include "drm_crtc_helper_internal.h" +#include "drm_internal.h" static bool drm_fbdev_emulation = true; module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); @@ -509,7 +510,7 @@ static int restore_fbdev_mode_legacy(struct drm_fb_helper *fb_helper) return ret; } -static int restore_fbdev_mode(struct drm_fb_helper *fb_helper) +static int restore_fbdev_mode_force(struct drm_fb_helper *fb_helper) { struct drm_device *dev = fb_helper->dev; @@ -519,6 +520,21 @@ static int restore_fbdev_mode(struct drm_fb_helper *fb_helper) return restore_fbdev_mode_legacy(fb_helper); } +static int restore_fbdev_mode(struct drm_fb_helper *fb_helper) +{ + struct drm_device *dev = fb_helper->dev; + int ret; + + if (!drm_master_internal_acquire(dev)) + return -EBUSY; + + ret = restore_fbdev_mode_force(fb_helper); + + drm_master_internal_release(dev); + + return ret; +} + /** * drm_fb_helper_restore_fbdev_mode_unlocked - restore fbdev configuration * @fb_helper: driver-allocated fbdev helper, can be NULL @@ -542,7 +558,17 @@ int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper) return 0; mutex_lock(&fb_helper->lock); - ret = restore_fbdev_mode(fb_helper); + /* + * TODO: + * We should bail out here if there is a master by dropping _force. + * Currently these igt tests fail if we do that: + * - kms_fbcon_fbt@psr + * - kms_fbcon_fbt@psr-suspend + * + * So first these tests need to be fixed so they drop master or don't + * have an fd open. + */ + ret = restore_fbdev_mode_force(fb_helper); do_delayed = fb_helper->delayed_hotplug; if (do_delayed) @@ -556,34 +582,6 @@ int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper) } EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked); -static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper) -{ - struct drm_device *dev = fb_helper->dev; - struct drm_crtc *crtc; - int bound = 0, crtcs_bound = 0; - - /* - * Sometimes user space wants everything disabled, so don't steal the - * display if there's a master. - */ - if (READ_ONCE(dev->master)) - return false; - - drm_for_each_crtc(crtc, dev) { - drm_modeset_lock(&crtc->mutex, NULL); - if (crtc->primary->fb) - crtcs_bound++; - if (crtc->primary->fb == fb_helper->fb) - bound++; - drm_modeset_unlock(&crtc->mutex); - } - - if (bound < crtcs_bound) - return false; - - return true; -} - #ifdef CONFIG_MAGIC_SYSRQ /* * restore fbcon display for all kms driver's using this helper, used for sysrq @@ -604,7 +602,7 @@ static bool drm_fb_helper_force_kernel_mode(void) continue; mutex_lock(&helper->lock); - ret = restore_fbdev_mode(helper); + ret = restore_fbdev_mode_force(helper); if (ret) error = true; mutex_unlock(&helper->lock); @@ -663,20 +661,22 @@ static void dpms_legacy(struct drm_fb_helper *fb_helper, int dpms_mode) static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) { struct drm_fb_helper *fb_helper = info->par; + struct drm_device *dev = fb_helper->dev; /* * For each CRTC in this fb, turn the connectors on/off. */ mutex_lock(&fb_helper->lock); - if (!drm_fb_helper_is_bound(fb_helper)) { - mutex_unlock(&fb_helper->lock); - return; - } + if (!drm_master_internal_acquire(dev)) + goto unlock; - if (drm_drv_uses_atomic_modeset(fb_helper->dev)) + if (drm_drv_uses_atomic_modeset(dev)) restore_fbdev_mode_atomic(fb_helper, dpms_mode == DRM_MODE_DPMS_ON); else dpms_legacy(fb_helper, dpms_mode); + + drm_master_internal_release(dev); +unlock: mutex_unlock(&fb_helper->lock); } @@ -1509,6 +1509,7 @@ static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info) int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info) { struct drm_fb_helper *fb_helper = info->par; + struct drm_device *dev = fb_helper->dev; int ret; if (oops_in_progress) @@ -1516,9 +1517,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info) mutex_lock(&fb_helper->lock); - if (!drm_fb_helper_is_bound(fb_helper)) { + if (!drm_master_internal_acquire(dev)) { ret = -EBUSY; - goto out; + goto unlock; } if (info->fix.visual == FB_VISUAL_TRUECOLOR) @@ -1528,7 +1529,8 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info) else ret = setcmap_legacy(cmap, info); -out: + drm_master_internal_release(dev); +unlock: mutex_unlock(&fb_helper->lock); return ret; @@ -1548,12 +1550,13 @@ int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg) { struct drm_fb_helper *fb_helper = info->par; + struct drm_device *dev = fb_helper->dev; struct drm_mode_set *mode_set; struct drm_crtc *crtc; int ret = 0; mutex_lock(&fb_helper->lock); - if (!drm_fb_helper_is_bound(fb_helper)) { + if (!drm_master_internal_acquire(dev)) { ret = -EBUSY; goto unlock; } @@ -1591,11 +1594,12 @@ int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd, } ret = 0; - goto unlock; + break; default: ret = -ENOTTY; } + drm_master_internal_release(dev); unlock: mutex_unlock(&fb_helper->lock); return ret; @@ -1847,15 +1851,18 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var, return -EBUSY; mutex_lock(&fb_helper->lock); - if (!drm_fb_helper_is_bound(fb_helper)) { - mutex_unlock(&fb_helper->lock); - return -EBUSY; + if (!drm_master_internal_acquire(dev)) { + ret = -EBUSY; + goto unlock; } if (drm_drv_uses_atomic_modeset(dev)) ret = pan_display_atomic(var, info); else ret = pan_display_legacy(var, info); + + drm_master_internal_release(dev); +unlock: mutex_unlock(&fb_helper->lock); return ret; @@ -2014,7 +2021,7 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, DRM_INFO("Cannot find any crtc or sizes\n"); /* First time: disable all crtc's.. */ - if (!fb_helper->deferred_setup && !READ_ONCE(fb_helper->dev->master)) + if (!fb_helper->deferred_setup) restore_fbdev_mode(fb_helper); return -EAGAIN; } @@ -3029,6 +3036,7 @@ EXPORT_SYMBOL(drm_fb_helper_initial_config); */ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) { + struct drm_device *dev = fb_helper->dev; int err = 0; if (!drm_fbdev_emulation || !fb_helper) @@ -3041,12 +3049,14 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) return err; } - if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) { + if (!fb_helper->fb || !drm_master_internal_acquire(dev)) { fb_helper->delayed_hotplug = true; mutex_unlock(&fb_helper->lock); return err; } + drm_master_internal_release(dev); + DRM_DEBUG_KMS("\n"); drm_setup_crtcs(fb_helper, fb_helper->fb->width, fb_helper->fb->height); diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index e19ac7ca602d..e6281d9f9c87 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -93,6 +93,8 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); int drm_master_open(struct drm_file *file_priv); void drm_master_release(struct drm_file *file_priv); +bool drm_master_internal_acquire(struct drm_device *dev); +void drm_master_internal_release(struct drm_device *dev); /* drm_sysfs.c */ extern struct class *drm_class;