From patchwork Mon Aug 10 08:51:38 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 6980731 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id A13579F39D for ; Mon, 10 Aug 2015 08:52:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B85922078E for ; Mon, 10 Aug 2015 08:52:12 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 7726A2078D for ; Mon, 10 Aug 2015 08:52:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E18F46E30D; Mon, 10 Aug 2015 01:52:10 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [87.106.93.118]) by gabe.freedesktop.org (Postfix) with ESMTP id B0BA06E305 for ; Mon, 10 Aug 2015 01:52:09 -0700 (PDT) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 43408773-1500048 for multiple; Mon, 10 Aug 2015 09:51:54 +0100 Received: by haswell.alporthouse.com (sSMTP sendmail emulation); Mon, 10 Aug 2015 09:51:43 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Mon, 10 Aug 2015 09:51:38 +0100 Message-Id: <1439196700-20045-1-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.5.0 X-Originating-IP: 78.156.65.138 X-Country: code=GB country="United Kingdom" ip=78.156.65.138 Subject: [Intel-gfx] [PATCH v3 1/3] drm/i915: Only update the current userptr worker X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The userptr worker allows for a slight race condition where upon there may two or more threads calling get_user_pages for the same object. When we have the array of pages, then we serialise the update of the object. However, the worker should only overwrite the obj->userptr.work pointer if and only if it is the active one. Currently we clear it for a secondary worker with the effect that we may rarely force a second lookup. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/i915_gem_userptr.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index d11901d590ac..800a5394aa1e 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -571,25 +571,25 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) struct get_pages_work *work = container_of(_work, typeof(*work), work); struct drm_i915_gem_object *obj = work->obj; struct drm_device *dev = obj->base.dev; - const int num_pages = obj->base.size >> PAGE_SHIFT; + const int npages = obj->base.size >> PAGE_SHIFT; struct page **pvec; int pinned, ret; ret = -ENOMEM; pinned = 0; - pvec = kmalloc(num_pages*sizeof(struct page *), + pvec = kmalloc(npages*sizeof(struct page *), GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY); if (pvec == NULL) - pvec = drm_malloc_ab(num_pages, sizeof(struct page *)); + pvec = drm_malloc_ab(npages, sizeof(struct page *)); if (pvec != NULL) { struct mm_struct *mm = obj->userptr.mm->mm; down_read(&mm->mmap_sem); - while (pinned < num_pages) { + while (pinned < npages) { ret = get_user_pages(work->task, mm, obj->userptr.ptr + pinned * PAGE_SIZE, - num_pages - pinned, + npages - pinned, !obj->userptr.read_only, 0, pvec + pinned, NULL); if (ret < 0) @@ -601,20 +601,20 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) } mutex_lock(&dev->struct_mutex); - if (obj->userptr.work != &work->work) { - ret = 0; - } else if (pinned == num_pages) { - ret = __i915_gem_userptr_set_pages(obj, pvec, num_pages); - if (ret == 0) { - list_add_tail(&obj->global_list, &to_i915(dev)->mm.unbound_list); - obj->get_page.sg = obj->pages->sgl; - obj->get_page.last = 0; - - pinned = 0; + if (obj->userptr.work == &work->work) { + if (pinned == npages) { + ret = __i915_gem_userptr_set_pages(obj, pvec, npages); + if (ret == 0) { + list_add_tail(&obj->global_list, + &to_i915(dev)->mm.unbound_list); + obj->get_page.sg = obj->pages->sgl; + obj->get_page.last = 0; + pinned = 0; + } } + obj->userptr.work = ERR_PTR(ret); } - obj->userptr.work = ERR_PTR(ret); obj->userptr.workers--; drm_gem_object_unreference(&obj->base); mutex_unlock(&dev->struct_mutex);