From patchwork Mon Sep 23 10:34:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 13809493 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 4685CCF9C69 for ; Mon, 23 Sep 2024 10:34:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A97B210E3D4; Mon, 23 Sep 2024 10:34:31 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 5433C10E3D4 for ; Mon, 23 Sep 2024 10:34:30 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 67A1BFEC; Mon, 23 Sep 2024 03:34:59 -0700 (PDT) Received: from e112269-lin.cambridge.arm.com (e112269-lin.cambridge.arm.com [10.1.194.64]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 50CF23F71A; Mon, 23 Sep 2024 03:34:29 -0700 (PDT) From: Steven Price To: Boris Brezillon , Liviu Dudau Cc: Steven Price , dri-devel@lists.freedesktop.org Subject: [PATCH] drm/panthor: Fix race when converting group handle to group object Date: Mon, 23 Sep 2024 11:34:06 +0100 Message-Id: <20240923103406.2509906-1-steven.price@arm.com> X-Mailer: git-send-email 2.39.5 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" XArray provides it's own internal lock which protects the internal array when entries are being simultaneously added and removed. However there is still a race between retrieving the pointer from the XArray and incrementing the reference count. To avoid this race simply hold the internal XArray lock when incrementing the reference count, this ensures there cannot be a racing call to xa_erase(). Fixes: de8548813824 ("drm/panthor: Add the scheduler logical block") Signed-off-by: Steven Price Reviewed-by: Boris Brezillon Reviewed-by: Liviu Dudau --- drivers/gpu/drm/panthor/panthor_sched.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c index 42afdf0ddb7e..0dbeebcf23b4 100644 --- a/drivers/gpu/drm/panthor/panthor_sched.c +++ b/drivers/gpu/drm/panthor/panthor_sched.c @@ -3242,6 +3242,18 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle) return 0; } +static struct panthor_group *group_from_handle(struct panthor_group_pool *pool, + u32 group_handle) +{ + struct panthor_group *group; + + xa_lock(&pool->xa); + group = group_get(xa_load(&pool->xa, group_handle)); + xa_unlock(&pool->xa); + + return group; +} + int panthor_group_get_state(struct panthor_file *pfile, struct drm_panthor_group_get_state *get_state) { @@ -3253,7 +3265,7 @@ int panthor_group_get_state(struct panthor_file *pfile, if (get_state->pad) return -EINVAL; - group = group_get(xa_load(&gpool->xa, get_state->group_handle)); + group = group_from_handle(gpool, get_state->group_handle); if (!group) return -EINVAL; @@ -3384,7 +3396,7 @@ panthor_job_create(struct panthor_file *pfile, job->call_info.latest_flush = qsubmit->latest_flush; INIT_LIST_HEAD(&job->node); - job->group = group_get(xa_load(&gpool->xa, group_handle)); + job->group = group_from_handle(gpool, group_handle); if (!job->group) { ret = -EINVAL; goto err_put_job;