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Message-ID: <5a9c38ec-1dc2-40d3-99eb-02b87be660a6@linux.intel.com>
Date: Thu, 18 Jan 2024 08:46:50 +0800
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Cc: baolu.lu@linux.intel.com, linux-pci@vger.kernel.org,
 iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v10 0/5] fix vt-d hard lockup when hotplug ATS capable
 device
Content-Language: en-US
To: Ethan Zhao <haifeng.zhao@linux.intel.com>, kevin.tian@intel.com,
 bhelgaas@google.com, dwmw2@infradead.org, will@kernel.org,
 robin.murphy@arm.com, lukas@wunner.de
References: <20231228170206.720675-1-haifeng.zhao@linux.intel.com>
 <1a2a4069-c737-4a3c-a2f6-cce06823331b@linux.intel.com>
 <3ee904e9-8a93-4bd9-8df7-6294885589e4@linux.intel.com>
 <42f7848a-0262-4871-b5dc-0e87beebfd11@linux.intel.com>
 <dcd27bc8-5eca-41ae-bb86-fd8e657ccfed@linux.intel.com>
 <d72d0a12-f3a4-4b4d-8b3b-5e59937a21d3@linux.intel.com>
From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <d72d0a12-f3a4-4b4d-8b3b-5e59937a21d3@linux.intel.com>
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On 1/17/24 5:00 PM, Ethan Zhao wrote:
> +       /*
> +        * If the ATS invalidation target device is gone this moment 
> (surprise
> +        * removed, died, no response) don't try this request again. this
> +        * request will not get valid result anymore. but the request was
> +        * already submitted to hardware and we predict to get a ITE in
> +        * followed batch of request, if so, it will get handled then.
> +        */
> +       if (target_pdev && !pci_device_is_present(target_pdev))
> +               return -EINVAL;

Again, we should not ignore the error triggered by the current request.
Do not leave it to the next one. The WAIT descriptor is a fence. Handle
everything within its boundary.

Best regards,
baolu