From patchwork Thu Sep 8 09:51:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Takashi Iwai X-Patchwork-Id: 12969869 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 9CB71ECAAD5 for ; Thu, 8 Sep 2022 09:52:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A67B510EA08; Thu, 8 Sep 2022 09:51:48 +0000 (UTC) Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by gabe.freedesktop.org (Postfix) with ESMTPS id C745610EA05 for ; Thu, 8 Sep 2022 09:51:21 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 6ED0333C1E; Thu, 8 Sep 2022 09:51:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1662630680; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8bQmlmjCrn4YhGnRqtiDDpH2w3JVupr54Crv1J9lwTM=; b=pLQQfJMDTd21UUwvA/wn7i2qwzoOcENYo9NGEFUYMl5jM/DHwdmRfLEl7MY8g7EbfgAYUS ArRUvDHnnjtN2s05bZNKtnxYXVGJ290RQrpwsyt4x/I82NGp+8ImcAYTO0Nuy+zdHgETsG TyPUV1dy9cVEr9jSmNrGKz+VKpoqjiU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1662630680; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8bQmlmjCrn4YhGnRqtiDDpH2w3JVupr54Crv1J9lwTM=; b=NMKMPqUlX8b1JKiMeJPw9SvbPuekuSB1kowwezSKatgliwKx5xBHGuNG+KY7MSoocJlrS/ 0thuObuLFfik7CAw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 5291F13A72; Thu, 8 Sep 2022 09:51:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id iD5sExi7GWNrUgAAMHmgww (envelope-from ); Thu, 08 Sep 2022 09:51:20 +0000 From: Takashi Iwai To: Thomas Zimmermann Subject: [PATCH v3 10/12] drm/udl: Fix inconsistent urbs.count value during udl_free_urb_list() Date: Thu, 8 Sep 2022 11:51:13 +0200 Message-Id: <20220908095115.23396-11-tiwai@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220908095115.23396-1-tiwai@suse.de> References: <20220908095115.23396-1-tiwai@suse.de> 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: Daniel Vetter , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" In the current design, udl_get_urb() may be called asynchronously during the driver freeing its URL list via udl_free_urb_list(). The problem is that the sync is determined by comparing the urbs.count and urbs.available fields, while we clear urbs.count field only once after udl_free_urb_list() finishes, i.e. during udl_free_urb_list(), the state becomes inconsistent. For fixing this inconsistency and also for hardening the locking scheme, this patch does a slight refactoring of the code around udl_get_urb() and udl_free_urb_list(). Now urbs.count is updated in the same spinlock at extracting a URB from the list in udl_free_url_list(). Acked-by: Thomas Zimmermann Signed-off-by: Takashi Iwai --- drivers/gpu/drm/udl/udl_drv.h | 8 +------ drivers/gpu/drm/udl/udl_main.c | 42 +++++++++++++++++++++++----------- 2 files changed, 30 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h index 5923d2e02bc8..d943684b5bbb 100644 --- a/drivers/gpu/drm/udl/udl_drv.h +++ b/drivers/gpu/drm/udl/udl_drv.h @@ -74,13 +74,7 @@ static inline struct usb_device *udl_to_usb_device(struct udl_device *udl) int udl_modeset_init(struct drm_device *dev); struct drm_connector *udl_connector_init(struct drm_device *dev); -struct urb *udl_get_urb_timeout(struct drm_device *dev, long timeout); - -#define GET_URB_TIMEOUT HZ -static inline struct urb *udl_get_urb(struct drm_device *dev) -{ - return udl_get_urb_timeout(dev, GET_URB_TIMEOUT); -} +struct urb *udl_get_urb(struct drm_device *dev); int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len); int udl_sync_pending_urbs(struct drm_device *dev); diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c index de28eeff3155..16aa4a655e7f 100644 --- a/drivers/gpu/drm/udl/udl_main.c +++ b/drivers/gpu/drm/udl/udl_main.c @@ -23,6 +23,8 @@ #define WRITES_IN_FLIGHT (20) #define MAX_VENDOR_DESCRIPTOR_SIZE 256 +static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout); + static int udl_parse_vendor_descriptor(struct udl_device *udl) { struct usb_device *udev = udl_to_usb_device(udl); @@ -146,15 +148,17 @@ void udl_urb_completion(struct urb *urb) static void udl_free_urb_list(struct drm_device *dev) { struct udl_device *udl = to_udl(dev); - int count = udl->urbs.count; struct urb_node *unode; struct urb *urb; DRM_DEBUG("Waiting for completes and freeing all render urbs\n"); /* keep waiting and freeing, until we've got 'em all */ - while (count--) { - urb = udl_get_urb_timeout(dev, MAX_SCHEDULE_TIMEOUT); + while (udl->urbs.count) { + spin_lock_irq(&udl->urbs.lock); + urb = udl_get_urb_locked(udl, MAX_SCHEDULE_TIMEOUT); + udl->urbs.count--; + spin_unlock_irq(&udl->urbs.lock); if (WARN_ON(!urb)) break; unode = urb->context; @@ -164,7 +168,8 @@ static void udl_free_urb_list(struct drm_device *dev) usb_free_urb(urb); kfree(unode); } - udl->urbs.count = 0; + + wake_up_all(&udl->urbs.sleep); } static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size) @@ -228,33 +233,44 @@ static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size) return udl->urbs.count; } -struct urb *udl_get_urb_timeout(struct drm_device *dev, long timeout) +static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout) { - struct udl_device *udl = to_udl(dev); - struct urb_node *unode = NULL; + struct urb_node *unode; - if (!udl->urbs.count) - return NULL; + assert_spin_locked(&udl->urbs.lock); /* Wait for an in-flight buffer to complete and get re-queued */ - spin_lock_irq(&udl->urbs.lock); if (!wait_event_lock_irq_timeout(udl->urbs.sleep, + !udl->urbs.count || !list_empty(&udl->urbs.list), udl->urbs.lock, timeout)) { DRM_INFO("wait for urb interrupted: available: %d\n", udl->urbs.available); - goto unlock; + return NULL; } + if (!udl->urbs.count) + return NULL; + unode = list_first_entry(&udl->urbs.list, struct urb_node, entry); list_del_init(&unode->entry); udl->urbs.available--; -unlock: - spin_unlock_irq(&udl->urbs.lock); return unode ? unode->urb : NULL; } +#define GET_URB_TIMEOUT HZ +struct urb *udl_get_urb(struct drm_device *dev) +{ + struct udl_device *udl = to_udl(dev); + struct urb *urb; + + spin_lock_irq(&udl->urbs.lock); + urb = udl_get_urb_locked(udl, GET_URB_TIMEOUT); + spin_unlock_irq(&udl->urbs.lock); + return urb; +} + int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len) { struct udl_device *udl = to_udl(dev);