From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82395C433FE for ; Thu, 14 Oct 2021 12:05:15 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 507A660E96 for ; Thu, 14 Oct 2021 12:05:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 507A660E96 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C7A946E0D4; Thu, 14 Oct 2021 12:05:14 +0000 (UTC) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id 381746E0D4; Thu, 14 Oct 2021 12:05:14 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10136"; a="214823909" X-IronPort-AV: E=Sophos;i="5.85,372,1624345200"; d="scan'208";a="214823909" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2021 05:05:13 -0700 X-IronPort-AV: E=Sophos;i="5.85,372,1624345200"; d="scan'208";a="481235759" Received: from thanners-mobl.ger.corp.intel.com (HELO [10.252.62.140]) ([10.252.62.140]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2021 05:05:12 -0700 To: Tvrtko Ursulin , intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org References: <20211013104123.1877827-1-maarten.lankhorst@linux.intel.com> <8625e3ca-57f8-e387-1742-808e3599786f@linux.intel.com> From: Maarten Lankhorst Message-ID: Date: Thu, 14 Oct 2021 14:05:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <8625e3ca-57f8-e387-1742-808e3599786f@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Subject: Re: [Intel-gfx] [PATCH] drm/i915: Use dma_resv_iter for waiting in i915_gem_object_wait_reservation. X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Op 14-10-2021 om 10:37 schreef Tvrtko Ursulin: > > On 13/10/2021 11:41, Maarten Lankhorst wrote: >> No memory should be allocated when calling i915_gem_object_wait, >> because it may be called to idle a BO when evicting memory. >> >> Fix this by using dma_resv_iter helpers to call >> i915_gem_object_wait_fence() on each fence, which cleans up the code a lot. >> Also remove dma_resv_prune, it's questionably. >> >> This will result in the following lockdep splat. > > > >> @@ -37,56 +36,17 @@ i915_gem_object_wait_reservation(struct dma_resv *resv, >>                    unsigned int flags, >>                    long timeout) >>   { >> -    struct dma_fence *excl; >> -    bool prune_fences = false; >> - >> -    if (flags & I915_WAIT_ALL) { >> -        struct dma_fence **shared; >> -        unsigned int count, i; >> -        int ret; >> +    struct dma_resv_iter cursor; >> +    struct dma_fence *fence; >>   -        ret = dma_resv_get_fences(resv, &excl, &count, &shared); >> -        if (ret) >> -            return ret; >> - >> -        for (i = 0; i < count; i++) { >> -            timeout = i915_gem_object_wait_fence(shared[i], >> -                                 flags, timeout); >> -            if (timeout < 0) >> -                break; >> +    dma_resv_iter_begin(&cursor, resv, flags & I915_WAIT_ALL); >> +    dma_resv_for_each_fence_unlocked(&cursor, fence) { >>   -            dma_fence_put(shared[i]); >> -        } >> - >> -        for (; i < count; i++) >> -            dma_fence_put(shared[i]); >> -        kfree(shared); >> - >> -        /* >> -         * If both shared fences and an exclusive fence exist, >> -         * then by construction the shared fences must be later >> -         * than the exclusive fence. If we successfully wait for >> -         * all the shared fences, we know that the exclusive fence >> -         * must all be signaled. If all the shared fences are >> -         * signaled, we can prune the array and recover the >> -         * floating references on the fences/requests. >> -         */ >> -        prune_fences = count && timeout >= 0; >> -    } else { >> -        excl = dma_resv_get_excl_unlocked(resv); >> +        timeout = i915_gem_object_wait_fence(fence, flags, timeout); >> +        if (timeout <= 0) >> +            break; > > You have another change in behaviour here, well a bug really. When userspace passes in zero timeout you fail to report activity in other than the first fence. Hmm, not necessarily, passing 0 to i915_gem_object_wait_fence timeout = 0 is a special case and means test only. It will return 1 on success. Of course it is still broken, I sent a reply to könig about it, hope it will get fixed and respun. :) ~Maarten