From patchwork Sun Sep 3 17:07:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Osipenko X-Patchwork-Id: 13373300 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 B420BCA0FE9 for ; Sun, 3 Sep 2023 17:09:13 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5630010E112; Sun, 3 Sep 2023 17:09:12 +0000 (UTC) Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by gabe.freedesktop.org (Postfix) with ESMTPS id DF94910E0FF for ; Sun, 3 Sep 2023 17:08:55 +0000 (UTC) Received: from workpc.. (109-252-153-31.dynamic.spd-mgts.ru [109.252.153.31]) (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: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id 6B46C66072B5; Sun, 3 Sep 2023 18:08:53 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1693760934; bh=Beunc+mcO9wcz3oaeRK21W7oP8OXFEtJrBh9G3jJNXw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ISdjD8eE29K3nwkheXywz+1PkycH+ZX+hGqDg9w6Hl0jWQ+vGyjy+G9B+9Q92mrPn aVjxBK5qcdKRcU1nIVRi82VydWmhfgkGIjGYMtK6AlUQT2b0ZcctVNI8G5OBjnUgqR ynHvQLApwnUsfrAhq5R7t8QU1bnWmvxQbpdmi7qX0+VdTUqsqweem0KPUtIbqReK8h dqH/GjVvUa/3GvBgBWEXzBdUJ8rwy5oxERCUbH9UsItVrwcyQ62tvZwDOVDE1ZRXEl yz5u2PPB/K6xnvvn4U2PXbuWkhpPMvGSid8CrAdwOWpszUDRf6dt9apK0Lm2vvA1j8 23ZawegxyzDrA== From: Dmitry Osipenko To: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , =?utf-8?q?Christian_K=C3=B6nig?= , Qiang Yu , Steven Price , Boris Brezillon , Emma Anholt , Melissa Wen Subject: [PATCH v16 12/20] drm/shmem-helper: Add and use lockless drm_gem_shmem_get_pages() Date: Sun, 3 Sep 2023 20:07:28 +0300 Message-ID: <20230903170736.513347-13-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230903170736.513347-1-dmitry.osipenko@collabora.com> References: <20230903170736.513347-1-dmitry.osipenko@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: kernel@collabora.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Add lockless drm_gem_shmem_get_pages() helper that skips taking reservation lock if pages_use_count is non-zero, leveraging from atomicity of the refcount_t. Make drm_gem_shmem_mmap() to utilize the new helper. Suggested-by: Boris Brezillon Signed-off-by: Dmitry Osipenko Reviewed-by: Boris Brezillon --- drivers/gpu/drm/drm_gem_shmem_helper.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index a0faef3e762d..d93ebfef20c7 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -227,6 +227,20 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) } EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) +{ + int ret; + + if (refcount_inc_not_zero(&shmem->pages_use_count)) + return 0; + + dma_resv_lock(shmem->base.resv, NULL); + ret = drm_gem_shmem_get_pages_locked(shmem); + dma_resv_unlock(shmem->base.resv); + + return ret; +} + static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) { int ret; @@ -610,10 +624,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct return ret; } - dma_resv_lock(shmem->base.resv, NULL); - ret = drm_gem_shmem_get_pages_locked(shmem); - dma_resv_unlock(shmem->base.resv); - + ret = drm_gem_shmem_get_pages(shmem); if (ret) return ret;