From patchwork Wed Aug 9 16:53:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Boris Brezillon X-Patchwork-Id: 13348186 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 03954C001B0 for ; Wed, 9 Aug 2023 16:53:42 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 673A310E46D; Wed, 9 Aug 2023 16:53:37 +0000 (UTC) Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by gabe.freedesktop.org (Postfix) with ESMTPS id DF93D10E469 for ; Wed, 9 Aug 2023 16:53:35 +0000 (UTC) Received: from localhost.localdomain (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by madras.collabora.co.uk (Postfix) with ESMTPSA id 0A8606607207; Wed, 9 Aug 2023 17:53:34 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1691600014; bh=et4jqipkVmssatdTyKRQlEK5mzAyY+19v1DvfrwdiX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X1hl8TJs8URYOHtq/bj5sOGUrp96IA7m18Kzn+LWM6hlM2l0x9ffKE1CnXMo2UzfJ i/hFBrxGolFk+MyRWM9dwOPEO+F7sKTvx1RXHKP9TduaW6O6DeVCFJUfw+jI+4ZSZS attOtg2zQxK0LnR1gCyudS3Sjp4Rcmid/XU0YRgWh/Wn4okGxfWDWZQRCCragAdQZ2 eW2nArexAKBuCa+AkTduCvuii50LSg8okEqId7m/DsI7TELCedSPbyxoC/rP/PyQe0 qoVdl9rVYoAhN4T3oeiJWdD/XxPUrLqbpAs6A+NLKfUH6uZsgspEqQUanl/ochJ8ZO bkrx5e4ZuUbHA== From: Boris Brezillon To: dri-devel@lists.freedesktop.org Subject: [PATCH v2 01/15] drm/shmem-helper: Make pages_use_count an atomic_t Date: Wed, 9 Aug 2023 18:53:14 +0200 Message-ID: <20230809165330.2451699-2-boris.brezillon@collabora.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809165330.2451699-1-boris.brezillon@collabora.com> References: <20230809165330.2451699-1-boris.brezillon@collabora.com> 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: Nicolas Boichat , Daniel Stone , Neil Armstrong , Liviu Dudau , Steven Price , Boris Brezillon , =?utf-8?b?Q2zDqW1lbnQgUMOp?= =?utf-8?b?cm9u?= , "Marty E . Plummer" , Robin Murphy , Faith Ekstrand Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This way we can grab a pages ref without acquiring the resv lock when pages_use_count > 0. Need to implement asynchronous map using the drm_gpuva_mgr when the map/unmap operation triggers a mapping split, requiring the new left/right regions to grab an additional page ref to guarantee that the pages stay pinned when the middle section is unmapped. Signed-off-by: Boris Brezillon --- drivers/gpu/drm/drm_gem_shmem_helper.c | 28 +++++++++++++------------ drivers/gpu/drm/lima/lima_gem.c | 2 +- drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 +- include/drm/drm_gem_shmem_helper.h | 2 +- 4 files changed, 18 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index a783d2245599..ca6938ea1b82 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -155,7 +155,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) if (shmem->pages) drm_gem_shmem_put_pages(shmem); - drm_WARN_ON(obj->dev, shmem->pages_use_count); + drm_WARN_ON(obj->dev, atomic_read(&shmem->pages_use_count)); dma_resv_unlock(shmem->base.resv); } @@ -172,14 +172,14 @@ static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) dma_resv_assert_held(shmem->base.resv); - if (shmem->pages_use_count++ > 0) + if (atomic_inc_return(&shmem->pages_use_count) > 1) return 0; pages = drm_gem_get_pages(obj); if (IS_ERR(pages)) { drm_dbg_kms(obj->dev, "Failed to get pages (%ld)\n", PTR_ERR(pages)); - shmem->pages_use_count = 0; + atomic_set(&shmem->pages_use_count, 0); return PTR_ERR(pages); } @@ -210,10 +210,10 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem) dma_resv_assert_held(shmem->base.resv); - if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count)) + if (drm_WARN_ON_ONCE(obj->dev, !atomic_read(&shmem->pages_use_count))) return; - if (--shmem->pages_use_count > 0) + if (atomic_dec_return(&shmem->pages_use_count) > 0) return; #ifdef CONFIG_X86 @@ -263,6 +263,10 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem) drm_WARN_ON(obj->dev, obj->import_attach); + /* If we are the first owner, we need to grab the lock. */ + if (atomic_inc_not_zero(&shmem->pages_use_count)) + return 0; + ret = dma_resv_lock_interruptible(shmem->base.resv, NULL); if (ret) return ret; @@ -286,6 +290,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem) drm_WARN_ON(obj->dev, obj->import_attach); + /* If we are the last owner, we need to grab the lock. */ + if (atomic_add_unless(&shmem->pages_use_count, -1, 1)) + return; + dma_resv_lock(shmem->base.resv, NULL); drm_gem_shmem_unpin_locked(shmem); dma_resv_unlock(shmem->base.resv); @@ -543,18 +551,12 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma) drm_WARN_ON(obj->dev, obj->import_attach); - dma_resv_lock(shmem->base.resv, NULL); - /* * We should have already pinned the pages when the buffer was first * mmap'd, vm_open() just grabs an additional reference for the new * mm the vma is getting copied into (ie. on fork()). */ - if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count)) - shmem->pages_use_count++; - - dma_resv_unlock(shmem->base.resv); - + drm_WARN_ON_ONCE(obj->dev, atomic_inc_return(&shmem->pages_use_count) == 1); drm_gem_vm_open(vma); } @@ -632,7 +634,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem, if (shmem->base.import_attach) return; - drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count); + drm_printf_indent(p, indent, "pages_use_count=%u\n", atomic_read(&shmem->pages_use_count)); drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count); drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr); } diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c index 4f9736e5f929..0116518b1601 100644 --- a/drivers/gpu/drm/lima/lima_gem.c +++ b/drivers/gpu/drm/lima/lima_gem.c @@ -47,7 +47,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) } bo->base.pages = pages; - bo->base.pages_use_count = 1; + atomic_set(&bo->base.pages_use_count, 1); mapping_set_unevictable(mapping); } diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index c0123d09f699..f66e63bf743e 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -487,7 +487,7 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, goto err_unlock; } bo->base.pages = pages; - bo->base.pages_use_count = 1; + atomic_set(&bo->base.pages_use_count, 1); } else { pages = bo->base.pages; if (pages[page_offset]) { diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index bf0c31aa8fbe..0661f87d3bda 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -37,7 +37,7 @@ struct drm_gem_shmem_object { * Reference count on the pages table. * The pages are put when the count reaches zero. */ - unsigned int pages_use_count; + atomic_t pages_use_count; /** * @madv: State for madvise