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 163BBC433F5 for ; Wed, 16 Feb 2022 11:54:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 38A1A10EA34; Wed, 16 Feb 2022 11:54:41 +0000 (UTC) Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6478610E999; Wed, 16 Feb 2022 11:54:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1645012480; x=1676548480; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=xj4HoD+9u0FMw8ZZdWCf3ehitqJtDMtcGbBS9QDZq7w=; b=HrzlZo7a/49wJHC0xo4C0c62MMfBVs1NwdqXxaxiTA+aQBbrUpiFh/7W +2Eob6QyxKuGh983acpfNKHKnYM5BhOSeYpUWE+oG4UYkcUsfNx8hlQrJ s7CK+0mmQoAXbizqPsxJc5NwjyI4N13kvno//UWZgoBEfV6plqpVeUOzK z1mOkWXakXF8URlf4wBPfvB630rDLfCtyFJCz//r0aHgUReWUVmQbO8xm suiqKzJBavNHiONChVnp2rEEh38+mQIiR6R6Y3XfNk9WNosCu06ShmlOC d7GqYh2oqPe55qHpxrEoOAfw/mKi0xoWYzv5DKVdZKG+sDRwCZVcWMYbp g==; X-IronPort-AV: E=McAfee;i="6200,9189,10259"; a="275167479" X-IronPort-AV: E=Sophos;i="5.88,373,1635231600"; d="scan'208";a="275167479" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Feb 2022 03:54:39 -0800 X-IronPort-AV: E=Sophos;i="5.88,373,1635231600"; d="scan'208";a="502992438" Received: from sphadnis-mobl1.amr.corp.intel.com (HELO [10.212.82.113]) ([10.212.82.113]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Feb 2022 03:54:38 -0800 Message-ID: <10cd355a-cc30-ac88-bed1-adcf91b033db@linux.intel.com> Date: Wed, 16 Feb 2022 11:54:35 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-US To: "Ceraolo Spurio, Daniele" , intel-gfx@lists.freedesktop.org References: <20220215011123.734572-1-daniele.ceraolospurio@intel.com> <5de141fa-014f-e95f-7dc8-74d95a9c6b14@linux.intel.com> <02e89fe1-a97d-1587-ea78-1e3a4518c649@intel.com> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc In-Reply-To: <02e89fe1-a97d-1587-ea78-1e3a4518c649@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Intel-gfx] [PATCH] drm/i915/guc: Initialize GuC submission locks and queues early X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 15/02/2022 16:39, Ceraolo Spurio, Daniele wrote: > On 2/15/2022 1:09 AM, Tvrtko Ursulin wrote: >> >> On 15/02/2022 01:11, Daniele Ceraolo Spurio wrote: >>> Move initialization of submission-related spinlock, lists and workers to >>> init_early. This fixes an issue where if the GuC init fails we might >>> still try to get the lock in the context cleanup code. Note that it is >> >> What's the worst case impact on non-debug builds aka is Fixes: required? > > There is no lock contention in this scenario and nothing is done within > the locked section (because submission is not initialized and all > contexts are marked as invalid), so no problems from the fact that the > lock doesn't work. Is that enough to avoid a fixes tag? If the "lock doesn't work" is benign due no chance of touching uninitialised memory and then deadlocking then it's good. I just couldn't read that part from the commit message and did not have time to go dig into the code. Regards, Tvrtko > Daniele > >> >> Regards, >> >> Tvrtko >> >>> safe to call the GuC context cleanup code even if the init failed >>> because all contexts are initialized with an invalid GuC ID, which will >>> cause the GuC side of the cleanup to be skipped, so it is easier to just >>> make sure the variables are initialized than to special case the cleanup >>> to handle the case when they're not. >>> >>> References: https://gitlab.freedesktop.org/drm/intel/-/issues/4932 >>> Signed-off-by: Daniele Ceraolo Spurio >>> Cc: Matthew Brost >>> Cc: John Harrison >>> --- >>>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 27 ++++++++++--------- >>>   1 file changed, 14 insertions(+), 13 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c >>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c >>> index b3a429a92c0da..2160da2c83cbf 100644 >>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c >>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c >>> @@ -1818,24 +1818,11 @@ int intel_guc_submission_init(struct >>> intel_guc *guc) >>>        */ >>>       GEM_BUG_ON(!guc->lrc_desc_pool); >>>   -    xa_init_flags(&guc->context_lookup, XA_FLAGS_LOCK_IRQ); >>> - >>> -    spin_lock_init(&guc->submission_state.lock); >>> -    INIT_LIST_HEAD(&guc->submission_state.guc_id_list); >>> -    ida_init(&guc->submission_state.guc_ids); >>> - INIT_LIST_HEAD(&guc->submission_state.destroyed_contexts); >>> -    INIT_WORK(&guc->submission_state.destroyed_worker, >>> -          destroyed_worker_func); >>> -    INIT_WORK(&guc->submission_state.reset_fail_worker, >>> -          reset_fail_worker_func); >>> - >>>       guc->submission_state.guc_ids_bitmap = >>>           bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL); >>>       if (!guc->submission_state.guc_ids_bitmap) >>>           return -ENOMEM; >>>   -    spin_lock_init(&guc->timestamp.lock); >>> -    INIT_DELAYED_WORK(&guc->timestamp.work, guc_timestamp_ping); >>>       guc->timestamp.ping_delay = (POLL_TIME_CLKS / >>> gt->clock_frequency + 1) * HZ; >>>       guc->timestamp.shift = gpm_timestamp_shift(gt); >>>   @@ -3831,6 +3818,20 @@ static bool __guc_submission_selected(struct >>> intel_guc *guc) >>>     void intel_guc_submission_init_early(struct intel_guc *guc) >>>   { >>> +    xa_init_flags(&guc->context_lookup, XA_FLAGS_LOCK_IRQ); >>> + >>> +    spin_lock_init(&guc->submission_state.lock); >>> +    INIT_LIST_HEAD(&guc->submission_state.guc_id_list); >>> +    ida_init(&guc->submission_state.guc_ids); >>> + INIT_LIST_HEAD(&guc->submission_state.destroyed_contexts); >>> +    INIT_WORK(&guc->submission_state.destroyed_worker, >>> +          destroyed_worker_func); >>> +    INIT_WORK(&guc->submission_state.reset_fail_worker, >>> +          reset_fail_worker_func); >>> + >>> +    spin_lock_init(&guc->timestamp.lock); >>> +    INIT_DELAYED_WORK(&guc->timestamp.work, guc_timestamp_ping); >>> + >>>       guc->submission_state.num_guc_ids = GUC_MAX_LRC_DESCRIPTORS; >>>       guc->submission_supported = __guc_submission_supported(guc); >>>       guc->submission_selected = __guc_submission_selected(guc); >