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 X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37444C433FF for ; Mon, 5 Aug 2019 15:46:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02CD12086D for ; Mon, 5 Aug 2019 15:46:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tEGanAP7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728680AbfHEPqC (ORCPT ); Mon, 5 Aug 2019 11:46:02 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:41816 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726847AbfHEPqC (ORCPT ); Mon, 5 Aug 2019 11:46:02 -0400 Received: by mail-wr1-f68.google.com with SMTP id c2so81679492wrm.8 for ; Mon, 05 Aug 2019 08:46:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=XU22kvabM0UAeUTon64K6xj93zNYGy477hyrLlnkqqs=; b=tEGanAP7V+39A/ck+Ix+YYs2iIz2rRrLG3XU2C8x50EPhssYveTxIH5YLXv1iO8NLP Lz439rOUOqi8fXqe4wfoWU2uGi9eXaUfCcF2bVNF3EATqzeUy6KBWm6gt78IINvpszPt qyztvbL0349xAwgCDsqhK8Ixv51qLMO7qDYQBNWVCQAvUxWW2iba0f/Zu/xMMyXl8sRn BBrYi5gfunSpGZ8dBDo2QlyRO/sBtG31jV9VvfbYOhAAq0m7eb6a9LzjtQvXwudBmNT+ voSa/3e+xAeaoMeVdUEotFwLUZnZj+Lgt+n1BoOEt3B44baXnBKBbSlhu/kjU1nK2CMJ ktew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=XU22kvabM0UAeUTon64K6xj93zNYGy477hyrLlnkqqs=; b=X+0kPhCTAQrgnOeT/CJj1UVhBvjWRv5R/LOaqAv1Gk6KAu/evkegED8xUNikFp25hE /CMlwvB81GQkp+xRV84wibyjy9D2iSFSG2sR7i7xXNRpZGPzybo/Ob5CvfM8BvpI37pt TVqFMgIkomrN+OWYCZMv6QxjyNNIpZajjHYn3oCOmL/LTIzh05ym3Y2tNxCi2SqstApH lyvGhOUBUhre0A8vcr5gVgtNN+I65JYrufE1zHSuqGSbkMjKX4QONYzIlLdScbv8DXFM 5v3XxT/3P0lXvglvtMHGBYk8/VdJMMJIcWojqfpeHYSbrecveg15b/4GmelvQQQYM9PS iCcg== X-Gm-Message-State: APjAAAV89fjxzj1bvkfMUGlXwqoXiB3Vt7FHyB016TL2aifcJlYdHCVG /Jqn1nPfiSUbLxV+IwBSMCA= X-Google-Smtp-Source: APXvYqzHdYFy9XMLdFXHPaQajeeRSYmmHeXb+ImtY7dbzuQuBVRElYCX9hzmLr8fW66jkiqAFEWqKA== X-Received: by 2002:adf:dfc5:: with SMTP id q5mr18757753wrn.142.1565019959731; Mon, 05 Aug 2019 08:45:59 -0700 (PDT) Received: from abel.fritz.box ([2a02:908:1252:fb60:fdbd:6233:4990:5a8d]) by smtp.gmail.com with ESMTPSA id 91sm171836865wrp.3.2019.08.05.08.45.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Aug 2019 08:45:59 -0700 (PDT) From: "=?UTF-8?q?Christian=20K=C3=B6nig?=" X-Google-Original-From: =?UTF-8?q?Christian=20K=C3=B6nig?= To: intel-gfx@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, chris@chris-wilson.co.uk Subject: [PATCH 5/5] dma-buf: nuke reservation_object seq number Date: Mon, 5 Aug 2019 17:45:54 +0200 Message-Id: <20190805154554.3476-5-christian.koenig@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190805154554.3476-1-christian.koenig@amd.com> References: <20190805154554.3476-1-christian.koenig@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org The only remaining use for this is to protect against setting a new exclusive fence while we grab both exclusive and shared. That can also be archived by looking if the exclusive fence has changed or not after completing the operation. Signed-off-by: Christian König --- drivers/dma-buf/dma-buf.c | 14 ++--- drivers/dma-buf/reservation.c | 58 +++++++------------ .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 8 +-- drivers/gpu/drm/i915/gem/i915_gem_busy.c | 11 ++-- include/linux/reservation.h | 3 - 5 files changed, 33 insertions(+), 61 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index f45bfb29ef96..c4ee4ccbfc40 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -199,7 +199,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) struct reservation_object_list *fobj; struct dma_fence *fence_excl; __poll_t events; - unsigned shared_count, seq; + unsigned shared_count; dmabuf = file->private_data; if (!dmabuf || !dmabuf->resv) @@ -214,16 +214,16 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) return 0; retry: - seq = read_seqcount_begin(&resv->seq); rcu_read_lock(); + fence_excl = rcu_dereference(resv->fence_excl); fobj = rcu_dereference(resv->fence); if (fobj) shared_count = fobj->shared_count; else shared_count = 0; - fence_excl = rcu_dereference(resv->fence_excl); - if (read_seqcount_retry(&resv->seq, seq)) { + + if (rcu_dereference(resv->fence_excl) != fence_excl) { rcu_read_unlock(); goto retry; } @@ -1157,7 +1157,6 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) struct reservation_object *robj; struct reservation_object_list *fobj; struct dma_fence *fence; - unsigned seq; int count = 0, attach_count, shared_count, i; size_t size = 0; @@ -1189,12 +1188,11 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) robj = buf_obj->resv; while (true) { - seq = read_seqcount_begin(&robj->seq); rcu_read_lock(); + fence = rcu_dereference(robj->fence_excl); fobj = rcu_dereference(robj->fence); shared_count = fobj ? fobj->shared_count : 0; - fence = rcu_dereference(robj->fence_excl); - if (!read_seqcount_retry(&robj->seq, seq)) + if (rcu_dereference(robj->fence_excl) != fence) break; rcu_read_unlock(); } diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c index 69c826553c72..d8ed6235a3eb 100644 --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -49,12 +49,6 @@ DEFINE_WD_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class); -struct lock_class_key reservation_seqcount_class; -EXPORT_SYMBOL(reservation_seqcount_class); - -const char reservation_seqcount_string[] = "reservation_seqcount"; -EXPORT_SYMBOL(reservation_seqcount_string); - /** * reservation_object_init - initialize a reservation object * @obj: the reservation object @@ -62,9 +56,6 @@ EXPORT_SYMBOL(reservation_seqcount_string); void reservation_object_init(struct reservation_object *obj) { ww_mutex_init(&obj->lock, &reservation_ww_class); - - __seqcount_init(&obj->seq, reservation_seqcount_string, - &reservation_seqcount_class); RCU_INIT_POINTER(obj->fence, NULL); RCU_INIT_POINTER(obj->fence_excl, NULL); } @@ -251,12 +242,10 @@ void reservation_object_add_excl_fence(struct reservation_object *obj, dma_fence_get(fence); preempt_disable(); - write_seqcount_begin(&obj->seq); - /* write_seqcount_begin provides the necessary memory barrier */ RCU_INIT_POINTER(obj->fence_excl, fence); + /* pointer update must be visible before we modify the shared_count */ if (old) - old->shared_count = 0; - write_seqcount_end(&obj->seq); + smp_store_mb(old->shared_count, 0); preempt_enable(); /* inplace update, no shared fences */ @@ -340,11 +329,8 @@ int reservation_object_copy_fences(struct reservation_object *dst, old = reservation_object_get_excl(dst); preempt_disable(); - write_seqcount_begin(&dst->seq); - /* write_seqcount_begin provides the necessary memory barrier */ RCU_INIT_POINTER(dst->fence_excl, new); - RCU_INIT_POINTER(dst->fence, dst_list); - write_seqcount_end(&dst->seq); + rcu_assign_pointer(dst->fence, dst_list); preempt_enable(); if (src_list) @@ -380,18 +366,14 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj, do { struct reservation_object_list *fobj; - unsigned int i, seq; + unsigned int i; size_t sz = 0; shared_count = i = 0; rcu_read_lock(); - seq = read_seqcount_begin(&obj->seq); - - fence_excl = rcu_dereference(obj->fence_excl); - if (fence_excl && !dma_fence_get_rcu(fence_excl)) - goto unlock; + fence_excl = dma_fence_get_rcu_safe(&obj->fence_excl); fobj = rcu_dereference(obj->fence); if (fobj) sz += sizeof(*shared) * fobj->shared_max; @@ -428,7 +410,8 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj, } } - if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) { + if (i != shared_count || + rcu_dereference(obj->fence_excl) != fence_excl) { while (i--) dma_fence_put(shared[i]); dma_fence_put(fence_excl); @@ -472,18 +455,17 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj, bool wait_all, bool intr, unsigned long timeout) { - struct dma_fence *fence; - unsigned seq, shared_count; + struct dma_fence *fence, *fence_excl; long ret = timeout ? timeout : 1; + unsigned shared_count; int i; retry: shared_count = 0; - seq = read_seqcount_begin(&obj->seq); rcu_read_lock(); i = -1; - fence = rcu_dereference(obj->fence_excl); + fence = fence_excl = rcu_dereference(obj->fence_excl); if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { if (!dma_fence_get_rcu(fence)) goto unlock_retry; @@ -524,13 +506,13 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj, } } + if (rcu_dereference(obj->fence_excl) != fence_excl) { + dma_fence_put(fence); + goto unlock_retry; + } + rcu_read_unlock(); if (fence) { - if (read_seqcount_retry(&obj->seq, seq)) { - dma_fence_put(fence); - goto retry; - } - ret = dma_fence_wait_timeout(fence, intr, ret); dma_fence_put(fence); if (ret > 0 && wait_all && (i + 1 < shared_count)) @@ -575,14 +557,15 @@ reservation_object_test_signaled_single(struct dma_fence *passed_fence) bool reservation_object_test_signaled_rcu(struct reservation_object *obj, bool test_all) { - unsigned seq, shared_count; + struct dma_fence *fence_excl; + unsigned shared_count; int ret; rcu_read_lock(); retry: + fence_excl = rcu_dereference(obj->fence_excl); ret = true; shared_count = 0; - seq = read_seqcount_begin(&obj->seq); if (test_all) { unsigned i; @@ -603,12 +586,11 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj, break; } - if (read_seqcount_retry(&obj->seq, seq)) + if (rcu_dereference(obj->fence_excl) != fence_excl) goto retry; } if (!shared_count) { - struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl); if (fence_excl) { ret = reservation_object_test_signaled_single( @@ -616,7 +598,7 @@ bool reservation_object_test_signaled_rcu(struct reservation_object *obj, if (ret < 0) goto retry; - if (read_seqcount_retry(&obj->seq, seq)) + if (rcu_dereference(obj->fence_excl) != fence_excl) goto retry; } } diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c index 1d3ee9c42f7e..a2a2ae592f20 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c @@ -251,12 +251,8 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo, new->shared_max = old->shared_max; new->shared_count = k; - /* Install the new fence list, seqcount provides the barriers */ - preempt_disable(); - write_seqcount_begin(&resv->seq); - RCU_INIT_POINTER(resv->fence, new); - write_seqcount_end(&resv->seq); - preempt_enable(); + /* Install the new fence list */ + rcu_assign_pointer(resv->fence, new); /* Drop the references to the removed fences or move them to ef_list */ for (i = j, k = 0; i < old->shared_count; ++i) { diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c index 6ad93a09968c..6e8a6e4f39ff 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c @@ -83,7 +83,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data, struct drm_i915_gem_busy *args = data; struct drm_i915_gem_object *obj; struct reservation_object_list *list; - unsigned int seq; + struct dma_fence *fence_excl; int err; err = -ENOENT; @@ -110,11 +110,9 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data, * */ retry: - seq = raw_read_seqcount(&obj->base.resv->seq); - /* Translate the exclusive fence to the READ *and* WRITE engine */ - args->busy = - busy_check_writer(rcu_dereference(obj->base.resv->fence_excl)); + fence_excl = rcu_dereference(obj->base.resv->fence_excl); + args->busy = busy_check_writer(fence_excl); /* Translate shared fences to READ set of engines */ list = rcu_dereference(obj->base.resv->fence); @@ -129,7 +127,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data, } } - if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq)) + if (args->busy && + rcu_dereference(obj->base.resv->fence_excl) != fence_excl) goto retry; err = 0; diff --git a/include/linux/reservation.h b/include/linux/reservation.h index 56b782fec49b..2b0b2a1aeae2 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -46,8 +46,6 @@ #include extern struct ww_class reservation_ww_class; -extern struct lock_class_key reservation_seqcount_class; -extern const char reservation_seqcount_string[]; /** * struct reservation_object_list - a list of shared fences @@ -71,7 +69,6 @@ struct reservation_object_list { */ struct reservation_object { struct ww_mutex lock; - seqcount_t seq; struct dma_fence __rcu *fence_excl; struct reservation_object_list __rcu *fence; -- 2.17.1