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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 987DBC54EE9 for ; Mon, 19 Sep 2022 15:28:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229968AbiISP22 (ORCPT ); Mon, 19 Sep 2022 11:28:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229919AbiISP2H (ORCPT ); Mon, 19 Sep 2022 11:28:07 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7E3DBF53; Mon, 19 Sep 2022 08:28:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663601286; x=1695137286; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=u4l9l32AEn0lwr5hQNu6et9ZUSUu5/s1P/GSY7BqxV8=; b=RBr9dMYEkscYPNxREFPPOpEd1OQIgaltUJ5sZqgQyN/3GtHOWun5Ut56 uA2izqgn1r3iC20tNj73q2z2AqxibrgmMUMrG4QscgjAx39J8qf26ZNkx d5A8KmXst8eblGNMk6zrOgWtVI2cIo0ElGM+2XW5cHMZqX4VRIJDhfIfi XN2mal5tbthxVoTECC/Pczs8Cvgd17fvS7c0MMvGNkMYqvmeNSe8ft0VO C08zJ6Q8njb8UeymO94K4FkCYUJk6NI84Upbluzz08sIY+zViL4+weSR8 pDT3IlqJC+5OwIezm+gv6TxNjhl11wpZQytApV/2WNv/X1gUz8z3EZS0o w==; X-IronPort-AV: E=McAfee;i="6500,9779,10475"; a="361168317" X-IronPort-AV: E=Sophos;i="5.93,328,1654585200"; d="scan'208";a="361168317" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2022 08:28:05 -0700 X-IronPort-AV: E=Sophos;i="5.93,328,1654585200"; d="scan'208";a="569693701" Received: from djiang5-mobl2.amr.corp.intel.com (HELO [10.212.95.27]) ([10.212.95.27]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2022 08:28:05 -0700 Message-ID: Date: Mon, 19 Sep 2022 08:28:04 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.2.2 Subject: Re: [PATCH] dmaengine: idxd: Set workqueue state to disabled before trying to re-enable Content-Language: en-US To: Jerry Snitselaar Cc: linux-kernel@vger.kernel.org, Fenghua Yu , Vinod Koul , dmaengine@vger.kernel.org, Fengqian Gao , "Shen, Xiaochen" References: <20220824192913.2425634-1-jsnitsel@redhat.com> <1417f4ce-2573-5c88-6c92-fda5c57ebceb@intel.com> <20220824211625.mfcyefi5yvasdt4r@cantor> <36ecf274-7be1-f50e-8ac0-9e99bc9ef556@intel.com> <20220917170524.23wxvkhieroyrofd@cantor> From: Dave Jiang In-Reply-To: <20220917170524.23wxvkhieroyrofd@cantor> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 9/17/2022 10:05 AM, Jerry Snitselaar wrote: > On Wed, Aug 24, 2022 at 03:19:51PM -0700, Dave Jiang wrote: >> On 8/24/2022 3:07 PM, Jerry Snitselaar wrote: >>> On Wed, 2022-08-24 at 14:59 -0700, Dave Jiang wrote: >>>> On 8/24/2022 2:16 PM, Jerry Snitselaar wrote: >>>>> On Wed, Aug 24, 2022 at 01:29:03PM -0700, Dave Jiang wrote: >>>>>> On 8/24/2022 12:29 PM, Jerry Snitselaar wrote: >>>>>>> For a software reset idxd_device_reinit() is called, which will >>>>>>> walk >>>>>>> the device workqueues to see which ones were enabled, and try >>>>>>> to >>>>>>> re-enable them. It keys off wq->state being iDXD_WQ_ENABLED, >>>>>>> but the >>>>>>> first thing idxd_enable_wq() will do is see that the state of >>>>>>> the >>>>>>> workqueue is enabled, and return 0 instead of attempting to >>>>>>> issue >>>>>>> a command to enable the workqueue. >>>>>>> >>>>>>> So once a workqueue is found that needs to be re-enabled, >>>>>>> set the state to disabled prior to calling idxd_enable_wq(). >>>>>>> This would accurately reflect the state if the enable fails >>>>>>> as well. >>>>>>> >>>>>>> Cc: Fenghua Yu >>>>>>> Cc: Dave Jiang >>>>>>> Cc: Vinod Koul >>>>>>> Cc: dmaengine@vger.kernel.org >>>>>>> Fixes: bfe1d56091c1 ("dmaengine: idxd: Init and probe for Intel >>>>>>> data accelerators") >>>>>>> Signed-off-by: Jerry Snitselaar >>>>>>> --- >>>>>>>    drivers/dma/idxd/irq.c | 1 + >>>>>>>    1 file changed, 1 insertion(+) >>>>>>> >>>>>>> diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c >>>>>>> index 743ead5ebc57..723eeb5328d6 100644 >>>>>>> --- a/drivers/dma/idxd/irq.c >>>>>>> +++ b/drivers/dma/idxd/irq.c >>>>>>> @@ -52,6 +52,7 @@ static void idxd_device_reinit(struct >>>>>>> work_struct *work) >>>>>>>                 struct idxd_wq *wq = idxd->wqs[i]; >>>>>>>                 if (wq->state == IDXD_WQ_ENABLED) { >>>>>>> +                       wq->state = IDXD_WQ_DISABLED; >>>>>> Might be better off to insert this line in >>>>>> idxd_wq_disable_cleanup(). I >>>>>> think that should put it in sane state. >>>>> I don't think that is called in the code path that I was lookng at. >>>>> I've been >>>>> looking at this bit of process_misc_interrupts(): >>>>> >>>>> halt: >>>>>         gensts.bits = ioread32(idxd->reg_base + >>>>> IDXD_GENSTATS_OFFSET); >>>>>         if (gensts.state == IDXD_DEVICE_STATE_HALT) { >>>>>                 idxd->state = IDXD_DEV_HALTED; >>>>>                 if (gensts.reset_type == >>>>> IDXD_DEVICE_RESET_SOFTWARE) { >>>>>                         /* >>>>>                          * If we need a software reset, we will >>>>> throw the work >>>>>                          * on a system workqueue in order to allow >>>>> interrupts >>>>>                          * for the device command completions. >>>>>                          */ >>>>>                         INIT_WORK(&idxd->work, idxd_device_reinit); >>>>>                         queue_work(idxd->wq, &idxd->work); >>>>>                 } else { >>>>>                         idxd->state = IDXD_DEV_HALTED; >>>>>                         idxd_wqs_quiesce(idxd); >>>>>                         idxd_wqs_unmap_portal(idxd); >>>>>                         spin_lock(&idxd->dev_lock); >>>>>                         idxd_device_clear_state(idxd); >>>>>                         dev_err(&idxd->pdev->dev, >>>>>                                 "idxd halted, need %s.\n", >>>>>                                 gensts.reset_type == >>>>> IDXD_DEVICE_RESET_FLR ? >>>>>                                 "FLR" : "system reset"); >>>>>                         spin_unlock(&idxd->dev_lock); >>>>>                         return -ENXIO; >>>>>                 } >>>>>         } >>>>> >>>>>         return 0; >>>>> } >>>>> >>>>> So it sees that the device is halted, and sticks >>>>> idxd_device_reinint() on that >>>>> workqueue. The idxd_device_reinit() has this loop to re-enable the >>>>> idxd wqs: >>>> idxd_device_reinit() should called idxd_device_reset() first. And >>>> that >>>> should at some point call idxd_wq_disable_cleanup() and clean up the >>>> states. >>>> >>>> https://elixir.bootlin.com/linux/v6.0-rc2/source/drivers/dma/idxd/irq.c#L42 >>>> >>>> https://elixir.bootlin.com/linux/v6.0-rc2/source/drivers/dma/idxd/device.c#L725 >>>> >>>> https://elixir.bootlin.com/linux/v6.0-rc2/source/drivers/dma/idxd/device.c#L711 >>>> >>>> https://elixir.bootlin.com/linux/v6.0-rc2/source/drivers/dma/idxd/device.c#L376 >>>> >>>> So if we stick the wq state reset in there, it should show up as >>>> "disabled" by the time we try to enable the WQs again. Does that look >>>> reasonable? >>>> >>> Ah, yeah I see that now. So, if it does set the state to disabled in >>> idxd_wq_disable_cleanup(), does it have another means to track which >>> wqs need to be re-enabled for that loop that happens after the >>> idxd_device_reset() call? >> Oh I see what you mean... So we can either do what you did or create a mask >> and mark the WQ that are "enabled" before reset. Maybe that's cleaner rather >> than relying on the side effect of the WQ state isn't cleared? Thoughts? >> > Circling back to this. Since max_wqs could theoretically go up to 2^8, I guess > this would need to be done with the bitmap_* functions? Hi Jerry, I wouldn't say never but I doubt any time soon for 2^8. DSA 1.0 has 8 WQs, and 2.0 (spec just went public) has 16. But yes we can use bitmap to be future proof. Are you currently working on a fix for this? Just don't want to duplicate effort if you already have something going. Thank you! > > Regards, > Jerry > >>>>>         for (i = 0; i < idxd->max_wqs; i++) { >>>>>                 struct idxd_wq *wq = idxd->wqs[i]; >>>>> >>>>>                 if (wq->state == IDXD_WQ_ENABLED) { >>>>>                         wq->state = IDXD_WQ_DISABLED; >>>>>                         rc = idxd_wq_enable(wq); >>>>>                         if (rc < 0) { >>>>>                                 dev_warn(dev, "Unable to re-enable >>>>> wq %s\n", >>>>>                                          dev_name(wq_confdev(wq))); >>>>>                         } >>>>>                 } >>>>>         } >>>>> >>>>> Once you go into idxd_wq_enable() though you get this check at the >>>>> beginning: >>>>> >>>>>         if (wq->state == IDXD_WQ_ENABLED) { >>>>>                 dev_dbg(dev, "WQ %d already enabled\n", wq->id); >>>>>                 return 0; >>>>>         } >>>>> >>>>> So IIUC it sees the device is halted, goes to reset it, figures out >>>>> a wq >>>>> should be re-enabled, calls idxd_wq_enable() which hits the check, >>>>> returns >>>>> 0 and the wq is never really re-enabled, though it will still have >>>>> wq state >>>>> set to IDXD_WQ_ENABLED. >>>>> >>>>> Or am I missing something? >>>>> >>>>> Regards, >>>>> Jerry >>>>> >>>>>>>                         rc = idxd_wq_enable(wq); >>>>>>>                         if (rc < 0) { >>>>>>>                                 dev_warn(dev, "Unable to re- >>>>>>> enable wq %s\n",