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 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 08465CF9C6B for ; Wed, 25 Sep 2024 14:29:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C6B7210E836; Wed, 25 Sep 2024 14:29:33 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="NbgzwPyi"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) by gabe.freedesktop.org (Postfix) with ESMTPS id B0E9F10E836 for ; Wed, 25 Sep 2024 14:29:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1727274573; x=1758810573; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=+8A8VM+p41FY4vQC1848ybWZziJjyrnjaS+NkPOsBlE=; b=NbgzwPyi6hN2aT3DEyT5LomNNXpEmf+0R2nJLqL8RLxODxs37DbeExAE EreGsir6ec16KyRm0D434kfjslfIzio93A9U/+ZIc/RY6Svq5ZikRAXgl T3i/09moWbBb6fU3pgVeutlmhHeNa5PEZ62qU7LMbuYW7rwdkvgvkHg3W jqWn56D6qVWFDt4vqI0ykHFu6FoCm2wOLFBbz1+sd2Qd5QJfMRomRFIMl BbXBcosVu/Eoo9jX19zdUTKGDn+kTapOzUxrS6cumBj7lDNkxZGxM/kcQ k+vYLe9rjfy/8wypb0nrG2yw6yBp6QtAWWnlpjxYOVarOXqhQeahQdXIE A==; X-CSE-ConnectionGUID: YwMXKT9vSTich2UgcnvnDg== X-CSE-MsgGUID: aiQ/+YEeQACs2agJCEfBdA== X-IronPort-AV: E=McAfee;i="6700,10204,11206"; a="37683168" X-IronPort-AV: E=Sophos;i="6.10,257,1719903600"; d="scan'208";a="37683168" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2024 07:29:23 -0700 X-CSE-ConnectionGUID: pYwNmG2QRNuBI9P9XkqjoA== X-CSE-MsgGUID: Aibjc9aqTReQKKsjz3cIzA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,257,1719903600"; d="scan'208";a="102622174" Received: from mlehtone-mobl.ger.corp.intel.com (HELO [10.245.244.236]) ([10.245.244.236]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2024 07:29:22 -0700 Message-ID: <0a1bbe76-c0ba-4d6e-aae7-0ff723bc334f@intel.com> Date: Wed, 25 Sep 2024 15:29:20 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] drm/xe: Take ref to job and job's fence in xe_sched_job_arm To: Matthew Brost , intel-xe@lists.freedesktop.org References: <20240924184541.2992459-1-matthew.brost@intel.com> Content-Language: en-GB From: Matthew Auld In-Reply-To: <20240924184541.2992459-1-matthew.brost@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On 24/09/2024 19:45, Matthew Brost wrote: > Fixes two possible races: > > - Submission to hardware signals job's fence before dma_fence_get at end > of run_job > - TDR fires and signals fence + free job before run_job completes > > Taking refs in xe_sched_job_arm to job and job's fence solves these by > ensure all refs collected before entering the DRM scheduler. The refs > are dropped in run_job and DRM scheduler respectfully. Safe as once > xe_sched_job_arm is called execution of job through DRM sched is > guaranteed. > > v2: > - Take job ref on resubmit (Matt Auld) > > Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2811 Maybe also: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2843 ? > Signed-off-by: Matthew Brost > Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") > Cc: Matthew Auld > Cc: # v6.8+ > --- > drivers/gpu/drm/xe/xe_execlist.c | 4 +++- > drivers/gpu/drm/xe/xe_gpu_scheduler.c | 17 +++++++++++++++++ > drivers/gpu/drm/xe/xe_gpu_scheduler.h | 6 +----- > drivers/gpu/drm/xe/xe_guc_submit.c | 11 +++++++---- > drivers/gpu/drm/xe/xe_sched_job.c | 5 ++--- > drivers/gpu/drm/xe/xe_sched_job_types.h | 1 - > 6 files changed, 30 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/xe/xe_execlist.c b/drivers/gpu/drm/xe/xe_execlist.c > index f3b71fe7a96d..b70706c9caf2 100644 > --- a/drivers/gpu/drm/xe/xe_execlist.c > +++ b/drivers/gpu/drm/xe/xe_execlist.c > @@ -309,11 +309,13 @@ execlist_run_job(struct drm_sched_job *drm_job) > struct xe_sched_job *job = to_xe_sched_job(drm_job); > struct xe_exec_queue *q = job->q; > struct xe_execlist_exec_queue *exl = job->q->execlist; > + struct dma_fence *fence = job->fence; > > q->ring_ops->emit_job(job); > xe_execlist_make_active(exl); > + xe_sched_job_put(job); > > - return dma_fence_get(job->fence); > + return fence; > } > > static void execlist_job_free(struct drm_sched_job *drm_job) > diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c > index c518d1d16d82..7ea0c8e9e7a9 100644 > --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c > +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c > @@ -4,6 +4,7 @@ > */ > > #include "xe_gpu_scheduler.h" > +#include "xe_sched_job.h" > > static void xe_sched_process_msg_queue(struct xe_gpu_scheduler *sched) > { > @@ -106,3 +107,19 @@ void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched, > list_add_tail(&msg->link, &sched->msgs); > xe_sched_process_msg_queue(sched); > } > + > +/** > + * xe_sched_resubmit_jobs() - Resubmit scheduler jobs > + * @sched: Xe GPU scheduler > + * > + * Take a ref all jobs on scheduler and resubmit. > + */ > +void xe_sched_resubmit_jobs(struct xe_gpu_scheduler *sched) > +{ > + struct drm_sched_job *s_job; > + > + list_for_each_entry(s_job, &sched->base.pending_list, list) > + xe_sched_job_get(to_xe_sched_job(s_job)); /* Paired with put in run_job */ > + > + drm_sched_resubmit_jobs(&sched->base); > +} > diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.h b/drivers/gpu/drm/xe/xe_gpu_scheduler.h > index cee9c6809fc0..ecbe5dd6664e 100644 > --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.h > +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.h > @@ -26,6 +26,7 @@ void xe_sched_add_msg(struct xe_gpu_scheduler *sched, > struct xe_sched_msg *msg); > void xe_sched_add_msg_locked(struct xe_gpu_scheduler *sched, > struct xe_sched_msg *msg); > +void xe_sched_resubmit_jobs(struct xe_gpu_scheduler *sched); > > static inline void xe_sched_msg_lock(struct xe_gpu_scheduler *sched) > { > @@ -47,11 +48,6 @@ static inline void xe_sched_tdr_queue_imm(struct xe_gpu_scheduler *sched) > drm_sched_tdr_queue_imm(&sched->base); > } > > -static inline void xe_sched_resubmit_jobs(struct xe_gpu_scheduler *sched) > -{ > - drm_sched_resubmit_jobs(&sched->base); > -} > - > static inline bool > xe_sched_invalidate_job(struct xe_sched_job *job, int threshold) > { > diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c > index fbbe6a487bbb..689279fdef80 100644 > --- a/drivers/gpu/drm/xe/xe_guc_submit.c > +++ b/drivers/gpu/drm/xe/xe_guc_submit.c > @@ -766,6 +766,7 @@ guc_exec_queue_run_job(struct drm_sched_job *drm_job) > struct xe_guc *guc = exec_queue_to_guc(q); > struct xe_device *xe = guc_to_xe(guc); > bool lr = xe_exec_queue_is_lr(q); > + struct dma_fence *fence = NULL; > > xe_assert(xe, !(exec_queue_destroyed(q) || exec_queue_pending_disable(q)) || > exec_queue_banned(q) || exec_queue_suspended(q)); > @@ -782,12 +783,14 @@ guc_exec_queue_run_job(struct drm_sched_job *drm_job) > > if (lr) { > xe_sched_job_set_error(job, -EOPNOTSUPP); > - return NULL; > - } else if (test_and_set_bit(JOB_FLAG_SUBMIT, &job->fence->flags)) { > - return job->fence; > + dma_fence_put(job->fence); /* Drop ref from xe_sched_job_arm */ > } else { > - return dma_fence_get(job->fence); > + fence = job->fence; > } > + > + xe_sched_job_put(job); /* Pairs with get from xe_sched_job_arm */ Only doubt is job being destroyed here. I think you were saying that guc_exec_queue_free_job(drm_job) can potentially happen before run_job() completes. But if that's the case can't the refcount reach zero here, and then caller of run_job() goes down in flames, since the drm_job is no longer a valid pointer, assuming the put() here frees the memory for it? > + > + return fence; > } > > static void guc_exec_queue_free_job(struct drm_sched_job *drm_job) > diff --git a/drivers/gpu/drm/xe/xe_sched_job.c b/drivers/gpu/drm/xe/xe_sched_job.c > index eeccc1c318ae..d0f4b908411f 100644 > --- a/drivers/gpu/drm/xe/xe_sched_job.c > +++ b/drivers/gpu/drm/xe/xe_sched_job.c > @@ -280,16 +280,15 @@ void xe_sched_job_arm(struct xe_sched_job *job) > fence = &chain->base; > } > > - job->fence = fence; > + xe_sched_job_get(job); /* Pairs with put in run_job */ > + job->fence = dma_fence_get(fence); /* Pairs with put in scheduler */ > drm_sched_job_arm(&job->drm); > } > > void xe_sched_job_push(struct xe_sched_job *job) > { > - xe_sched_job_get(job); > trace_xe_sched_job_exec(job); > drm_sched_entity_push_job(&job->drm); > - xe_sched_job_put(job); > } > > /** > diff --git a/drivers/gpu/drm/xe/xe_sched_job_types.h b/drivers/gpu/drm/xe/xe_sched_job_types.h > index 0d3f76fb05ce..8ed95e1a378f 100644 > --- a/drivers/gpu/drm/xe/xe_sched_job_types.h > +++ b/drivers/gpu/drm/xe/xe_sched_job_types.h > @@ -40,7 +40,6 @@ struct xe_sched_job { > * @fence: dma fence to indicate completion. 1 way relationship - job > * can safely reference fence, fence cannot safely reference job. > */ > -#define JOB_FLAG_SUBMIT DMA_FENCE_FLAG_USER_BITS > struct dma_fence *fence; > /** @user_fence: write back value when BB is complete */ > struct {