From: Bart Van Assche <bvanassche@acm.org>
To: Adrian Hunter <adrian.hunter@intel.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: "James E . J . Bottomley" <jejb@linux.ibm.com>,
Bean Huo <huobean@gmail.com>, Avri Altman <avri.altman@wdc.com>,
Alim Akhtar <alim.akhtar@samsung.com>,
Can Guo <cang@codeaurora.org>,
Asutosh Das <asutoshd@codeaurora.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Wei Li <liwei213@huawei.com>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH V4 1/3] scsi: ufs: Fix error handler clear ua deadlock
Date: Mon, 20 Sep 2021 13:33:33 -0700 [thread overview]
Message-ID: <75ad3b8f-5bc9-c9e0-71fe-1c7c0c3c58a4@acm.org> (raw)
In-Reply-To: <85faef6e-d136-c0ec-cdc2-4a9e6c6223ee@intel.com>
On 9/20/21 10:30 AM, Adrian Hunter wrote:
> On 17/09/21 8:58 pm, Bart Van Assche wrote:
>> The same comment applies to the commands sent by ufshcd_probe_hba() I think.
>> If you would like to address this issue, how about passing the flag
>> BLK_MQ_REQ_RESERVED to the blk_get_request() call in ufshcd_exec_dev_cmd()?
>> The following additional changes are required to make this work:
>> * Add a 'reserved_tags' member to struct scsi_host_template, e.g. close to
>> tag_alloc_policy.
>> * Modify scsi_mq_setup_tags() such that it copies the reserved_tags value
>> from the host template into tag_set->reserved_tags.
>> * Set 'reserved_tags' in the UFS driver SCSI host template.
>
> I think these things only happen on the reset path, so all the slots should
> be free, even if all the tags are allocated. With some care, it might be
> possible simply to grab a free slot.
Hmm ... my understanding is that ufshcd_try_to_abort_task() may fail and hence
that it is not guaranteed that there will be free slot. Anyway, I'm fine with
the patch in its current shape and implementing the mechanism explained in my
previous email at a later time.
Bart.
next prev parent reply other threads:[~2021-09-20 20:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 17:02 [PATCH V4 0/3] scsi: ufs: Let devices remain runtime suspended during system suspend Adrian Hunter
2021-09-16 17:02 ` [PATCH V4 1/3] scsi: ufs: Fix error handler clear ua deadlock Adrian Hunter
2021-09-17 16:09 ` Bart Van Assche
2021-09-17 17:39 ` Adrian Hunter
2021-09-17 17:58 ` Bart Van Assche
2021-09-20 17:30 ` Adrian Hunter
2021-09-20 20:33 ` Bart Van Assche [this message]
2021-09-16 17:02 ` [PATCH V4 2/3] scsi: ufs: Fix runtime PM dependencies getting broken Adrian Hunter
2021-09-16 17:02 ` [PATCH V4 3/3] scsi: ufs: Let devices remain runtime suspended during system suspend Adrian Hunter
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