From: Can Guo <cang@codeaurora.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
andy.teng@mediatek.com, jejb@linux.ibm.com,
chun-hung.wu@mediatek.com, kuohong.wang@mediatek.com,
linux-kernel@vger.kernel.org, asutoshd@codeaurora.org,
Avri Altman <Avri.Altman@wdc.com>,
linux-mediatek@lists.infradead.org, peter.wang@mediatek.com,
alim.akhtar@samsung.com, matthias.bgg@gmail.com,
Stanley Chu <stanley.chu@mediatek.com>,
chaotian.jing@mediatek.com, cc.chou@mediatek.com,
linux-arm-kernel@lists.infradead.org, beanhuo@micron.com
Subject: Re: [PATCH v4] scsi: ufs: Cleanup completed request without interrupt notification
Date: Fri, 31 Jul 2020 16:00:28 +0800 [thread overview]
Message-ID: <8b0a158a7c3ee2165e09290996521ffc@codeaurora.org> (raw)
In-Reply-To: <97f1dfb0-41b6-0249-3e82-cae480b0efb6@acm.org>
Hi Bart,
On 2020-07-31 12:06, Bart Van Assche wrote:
> On 2020-07-30 18:30, Stanley Chu wrote:
>> On Mon, 2020-07-27 at 11:18 +0000, Avri Altman wrote:
>>> Looks good to me.
>>> But better wait and see if Bart have any further reservations.
>>
>> Would you have any further suggestions?
>
> Today is the first time that I took a look at ufshcd_abort(). The
> approach of that function looks wrong to me. This is how I think that a
> SCSI LLD abort handler should work:
> (1) Serialize against the completion path
> (__ufshcd_transfer_req_compl()) such that it cannot happen that the
> abort handler and the regular completion path both call
> cmd->scsi_done(cmd) at the same time. I'm not sure whether an existing
> synchronization object can be used for this purpose or whether a new
> synchronization object has to be introduced to serialize scsi_done()
> calls from __ufshcd_transfer_req_compl() and ufshcd_abort().
> (2) While holding that synchronization object, check whether the SCSI
> command is still outstanding. If so, submit a SCSI abort TMR to the
> device.
> (3) If the command has been aborted, call scsi_done() and return
> SUCCESS. If aborting failed and the command is still in progress,
> return
> FAILED.
>
> An example is available in srp_abort() in
> drivers/infiniband/ulp/srp/ib_srp.c.
>
> Bart.
AFAIK, sychronization of scsi_done is not a problem here, because scsi
layer
use the atomic state, namely SCMD_STATE_COMPLETE, of a scsi cmd to
prevent
the concurrency of abort and real completion of it.
Check func scsi_times_out(), hope it helps.
enum blk_eh_timer_return scsi_times_out(struct request *req)
{
...
if (rtn == BLK_EH_DONE) {
/*
* Set the command to complete first in order to prevent
a real
* completion from releasing the command while error
handling
* is using it. If the command was already completed,
then the
* lower level driver beat the timeout handler, and it
is safe
* to return without escalating error recovery.
*
* If timeout handling lost the race to a real
completion, the
* block layer may ignore that due to a fake timeout
injection,
* so return RESET_TIMER to allow error handling another
shot
* at this command.
*/
if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
return BLK_EH_RESET_TIMER;
if (scsi_abort_command(scmd) != SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT);
scsi_eh_scmd_add(scmd);
}
}
}
Thanks,
Can Guo.
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek
next prev parent reply other threads:[~2020-07-31 9:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-24 14:02 [PATCH v4] scsi: ufs: Cleanup completed request without interrupt notification Stanley Chu
2020-07-27 11:18 ` Avri Altman
2020-07-31 1:30 ` Stanley Chu
2020-07-31 4:06 ` Bart Van Assche
2020-07-31 8:00 ` Can Guo [this message]
2020-07-31 16:51 ` Bart Van Assche
2020-07-31 23:17 ` Can Guo
2020-08-03 3:00 ` Stanley Chu
2020-08-03 5:14 ` Can Guo
2020-08-03 5:27 ` Stanley Chu
2020-08-03 3:12 ` Bart Van Assche
2020-08-03 5:07 ` Can Guo
2020-08-04 10:01 ` Can Guo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8b0a158a7c3ee2165e09290996521ffc@codeaurora.org \
--to=cang@codeaurora.org \
--cc=Avri.Altman@wdc.com \
--cc=alim.akhtar@samsung.com \
--cc=andy.teng@mediatek.com \
--cc=asutoshd@codeaurora.org \
--cc=beanhuo@micron.com \
--cc=bvanassche@acm.org \
--cc=cc.chou@mediatek.com \
--cc=chaotian.jing@mediatek.com \
--cc=chun-hung.wu@mediatek.com \
--cc=jejb@linux.ibm.com \
--cc=kuohong.wang@mediatek.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=matthias.bgg@gmail.com \
--cc=peter.wang@mediatek.com \
--cc=stanley.chu@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).