From patchwork Wed Nov 17 12:28:28 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Hellstrom X-Patchwork-Id: 332701 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id oAHCTpNx030285 for ; Wed, 17 Nov 2010 12:30:11 GMT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 70217A0EF5 for ; Wed, 17 Nov 2010 04:29:51 -0800 (PST) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from smtp-outbound-2.vmware.com (smtp-outbound-2.vmware.com [65.115.85.73]) by gabe.freedesktop.org (Postfix) with ESMTP id A14D0A0F01 for ; Wed, 17 Nov 2010 04:28:48 -0800 (PST) Received: from mailhost2.vmware.com (mailhost2.vmware.com [10.16.67.167]) by smtp-outbound-2.vmware.com (Postfix) with ESMTP id 9763C50006; Wed, 17 Nov 2010 04:28:48 -0800 (PST) Received: from localhost.localdomain (sslvpn-dhcp28.eng.vmware.com [10.20.254.28]) by mailhost2.vmware.com (Postfix) with ESMTP id 3ADB28E5B8; Wed, 17 Nov 2010 04:28:47 -0800 (PST) From: Thomas Hellstrom To: airlied@redhat.com Subject: [PATCH 2/5] drm/ttm: Don't deadlock on recursive multi-bo reservations Date: Wed, 17 Nov 2010 13:28:28 +0100 Message-Id: <1289996911-14329-3-git-send-email-thellstrom@vmware.com> X-Mailer: git-send-email 1.6.2.5 In-Reply-To: <1289996911-14329-2-git-send-email-thellstrom@vmware.com> References: <1289996911-14329-1-git-send-email-thellstrom@vmware.com> <1289996911-14329-2-git-send-email-thellstrom@vmware.com> Cc: Thomas Hellstrom , dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dri-devel-bounces+patchwork-dri-devel=patchwork.kernel.org@lists.freedesktop.org Errors-To: dri-devel-bounces+patchwork-dri-devel=patchwork.kernel.org@lists.freedesktop.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]); Wed, 17 Nov 2010 12:30:11 +0000 (UTC) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 9ef893d..5d87508 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -223,9 +223,18 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, /** * Deadlock avoidance for multi-bo reserving. */ - if (use_sequence && bo->seq_valid && - (sequence - bo->val_seq < (1 << 31))) { - return -EAGAIN; + if (use_sequence && bo->seq_valid) { + /** + * We've already reserved this one. + */ + if (unlikely(sequence == bo->val_seq)) + return -EDEADLK; + /** + * Already reserved by a thread that will not back + * off for us. We need to back off. + */ + if (unlikely(sequence - bo->val_seq < (1 << 31))) + return -EAGAIN; } if (no_wait) diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h index 95068e6..1e25a40 100644 --- a/include/drm/ttm/ttm_bo_driver.h +++ b/include/drm/ttm/ttm_bo_driver.h @@ -859,6 +859,9 @@ extern void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo); * try again. (only if use_sequence == 1). * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by * a signal. Release all buffer reservations and return to user-space. + * -EBUSY: The function needed to sleep, but @no_wait was true + * -EDEADLK: Bo already reserved using @sequence. This error code will only + * be returned if @use_sequence is set to true. */ extern int ttm_bo_reserve(struct ttm_buffer_object *bo, bool interruptible, @@ -868,11 +871,27 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo, /** * ttm_bo_reserve_locked: * - * Similar to ttm_bo_reserve, but must be called with the glob::lru_lock - * spinlock held, and will not remove reserved buffers from the lru lists. + * @bo: A pointer to a struct ttm_buffer_object. + * @interruptible: Sleep interruptible if waiting. + * @no_wait: Don't sleep while trying to reserve, rather return -EBUSY. + * @use_sequence: If @bo is already reserved, Only sleep waiting for + * it to become unreserved if @sequence < (@bo)->sequence. + * + * Must be called with struct ttm_bo_global::lru_lock held, + * and will not remove reserved buffers from the lru lists. * The function may release the LRU spinlock if it needs to sleep. + * Otherwise identical to ttm_bo_reserve. + * + * Returns: + * -EAGAIN: The reservation may cause a deadlock. + * Release all buffer reservations, wait for @bo to become unreserved and + * try again. (only if use_sequence == 1). + * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by + * a signal. Release all buffer reservations and return to user-space. + * -EBUSY: The function needed to sleep, but @no_wait was true + * -EDEADLK: Bo already reserved using @sequence. This error code will only + * be returned if @use_sequence is set to true. */ - extern int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, bool interruptible, bool no_wait, bool use_sequence,