From: Martin Kepplinger <martin.kepplinger@puri.sm> To: Alan Stern <stern@rowland.harvard.edu> Cc: James Bottomley <James.Bottomley@hansenpartnership.com>, Bart Van Assche <bvanassche@acm.org>, Can Guo <cang@codeaurora.org>, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@puri.sm Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release Date: Mon, 10 Aug 2020 14:03:17 +0200 [thread overview] Message-ID: <60150284-be13-d373-5448-651b72a7c4c9@puri.sm> (raw) In-Reply-To: <20200809152643.GA277165@rowland.harvard.edu> On 09.08.20 17:26, Alan Stern wrote: > On Sun, Aug 09, 2020 at 11:20:22AM +0200, Martin Kepplinger wrote: >> Hey Alan, I'm really glad for that, I suspected some of this but I have >> little experience in scsi/block layers, so that is super helpful. >> >> I'd appreciate an opinion on the below workaround that *seems* to work >> now (let's see, I had thought so before :) >> >> Whether or not this helps to find a real solution, let's see. But >> integration of such a flag in the error handling paths is what's >> interesting for now: >> >> >> --- a/drivers/scsi/scsi_error.c >> +++ b/drivers/scsi/scsi_error.c >> @@ -565,6 +565,17 @@ int scsi_check_sense(struct scsi_cmnd *scmd) >> return NEEDS_RETRY; >> } >> } >> + if (scmd->device->expecting_media_change) { >> + if (sshdr.asc == 0x28 && sshdr.ascq == 0x00) { >> + /* clear expecting_media_change in >> + * scsi_noretry_cmd() because we need >> + * to override possible "failfast" overrides >> + * that block readahead can cause. >> + */ >> + return NEEDS_RETRY; > > This is a somewhat fragile approach. You don't know for certain that > scsi_noretry_cmd will be called. Also, scsi_noretry_cmd can be called > from other places. > > It would be better to clear the expecting_media_change flag just before > returning from scsi_decide_disposition. That way its use is localized > to one routine, not spread out between two. > > Alan Stern > Hi Alan, maybe you're right. I initially just thought that I'd allow for specific error codes in scsi_noretry_cmd() to return non-NULL (BUS_BUSY, PARITY, ERROR) despite having the flag set. The below version works equally fine for me but I'm not sure if it's actually more safe. James, when exposing a new writable sysfs option like "suspend_no_media_change"(?) that drivers can check before setting the new "expecting_media_change" flag (during resume), would this addition make sense to you? thanks, martin --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -565,6 +565,18 @@ int scsi_check_sense(struct scsi_cmnd *scmd) return NEEDS_RETRY; } } + if (scmd->device->expecting_media_change) { + if (sshdr.asc == 0x28 && sshdr.ascq == 0x00) { + /* + * clear the expecting_media_change in + * scsi_decide_disposition() because we + * need to catch possible "fail fast" overrides + * that block readahead can cause. + */ + return NEEDS_RETRY; + } + } + /* * we might also expect a cc/ua if another LUN on the target * reported a UA with an ASC/ASCQ of 3F 0E - @@ -1944,9 +1956,19 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd) * the request was not marked fast fail. Note that above, * even if the request is marked fast fail, we still requeue * for queue congestion conditions (QUEUE_FULL or BUSY) */ - if ((++scmd->retries) <= scmd->allowed - && !scsi_noretry_cmd(scmd)) { - return NEEDS_RETRY; + if ((++scmd->retries) <= scmd->allowed) { + /* + * but scsi_noretry_cmd() cannot override the + * expecting_media_change flag. + */ + if (!scsi_noretry_cmd(scmd) || + scmd->device->expecting_media_change) { + scmd->device->expecting_media_change = 0; + return NEEDS_RETRY; + } else { + /* marked fast fail and not expected. */ + return SUCCESS; + } } else { /* * no more retries - report this one back to upper level. diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index d90fefffe31b..bb583e403b81 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -3642,6 +3642,8 @@ static int sd_resume(struct device *dev) if (!sdkp) /* E.g.: runtime resume at the start of sd_probe() */ return 0; + sdkp->device->expecting_media_change = 1; + if (!sdkp->device->manage_start_stop) return 0; diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index bc5909033d13..f5fc1af68e00 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -169,6 +169,7 @@ struct scsi_device { * this device */ unsigned expecting_cc_ua:1; /* Expecting a CHECK_CONDITION/UNIT_ATTN * because we did a bus reset. */ + unsigned expecting_media_change:1; unsigned use_10_for_rw:1; /* first try 10-byte read / write */ unsigned use_10_for_ms:1; /* first try 10-byte mode sense/select */ unsigned set_dbd_for_ms:1; /* Set "DBD" field in mode sense */ --
next prev parent reply other threads:[~2020-08-10 12:03 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-23 11:10 Martin Kepplinger 2020-06-24 13:33 ` Bart Van Assche 2020-06-25 8:16 ` Martin Kepplinger 2020-06-25 14:52 ` Alan Stern 2020-06-26 3:53 ` Bart Van Assche 2020-06-26 15:07 ` Bart Van Assche 2020-06-26 15:44 ` Alan Stern 2020-06-28 2:37 ` Bart Van Assche 2020-06-28 13:10 ` Alan Stern 2020-06-29 9:42 ` Martin Kepplinger 2020-06-29 16:15 ` Alan Stern 2020-06-29 16:56 ` Bart Van Assche 2020-06-29 17:40 ` Alan Stern 2020-06-30 3:33 ` Martin Kepplinger 2020-06-30 13:38 ` Alan Stern 2020-06-30 15:59 ` Bart Van Assche 2020-06-30 18:02 ` Alan Stern 2020-06-30 19:23 ` Bart Van Assche 2020-06-30 19:38 ` Alan Stern 2020-06-30 23:31 ` Bart Van Assche 2020-07-01 0:49 ` Alan Stern 2020-07-06 16:41 ` Alan Stern 2020-07-28 7:02 ` Martin Kepplinger 2020-07-28 20:02 ` Alan Stern 2020-07-29 14:12 ` Martin Kepplinger 2020-07-29 14:32 ` Alan Stern 2020-07-29 14:44 ` Martin K. Petersen 2020-07-29 14:56 ` Alan Stern 2020-07-29 14:46 ` James Bottomley 2020-07-29 14:53 ` James Bottomley 2020-07-29 15:40 ` Martin Kepplinger 2020-07-29 15:44 ` James Bottomley 2020-07-29 16:43 ` Martin Kepplinger 2020-07-29 18:25 ` Alan Stern 2020-07-29 18:29 ` James Bottomley 2020-07-30 8:52 ` Martin Kepplinger 2020-07-30 8:54 ` Martin Kepplinger 2020-07-30 15:10 ` Alan Stern 2020-08-04 9:39 ` Martin Kepplinger 2020-08-07 9:51 ` Martin Kepplinger 2020-08-07 14:30 ` Alan Stern 2020-08-08 6:59 ` Martin Kepplinger 2020-08-08 15:05 ` Alan Stern 2020-08-09 9:20 ` Martin Kepplinger 2020-08-09 15:26 ` Alan Stern 2020-08-10 12:03 ` Martin Kepplinger [this message] 2020-08-10 14:13 ` Alan Stern 2020-08-11 7:55 ` Martin Kepplinger 2020-08-11 13:48 ` Alan Stern 2020-08-23 14:57 ` [PATCH] block: Fix bug in runtime-resume handling Alan Stern 2020-08-24 17:48 ` Bart Van Assche 2020-08-24 20:13 ` Alan Stern 2020-08-26 7:48 ` Martin Kepplinger 2020-08-27 17:42 ` Martin Kepplinger 2020-08-27 20:29 ` Alan Stern 2020-08-29 7:24 ` Martin Kepplinger 2020-08-29 15:26 ` Alan Stern 2020-08-29 16:33 ` Martin Kepplinger 2020-08-29 18:56 ` Alan Stern 2020-08-30 0:38 ` Bart Van Assche 2020-08-30 1:06 ` Alan Stern 2020-07-29 15:40 ` [PATCH] scsi: sd: add runtime pm to open / release Alan Stern 2020-07-29 15:49 ` James Bottomley 2020-07-29 16:17 ` Alan Stern 2020-07-29 15:52 ` Martin Kepplinger 2020-07-29 18:10 ` Douglas Gilbert 2020-07-30 8:05 ` Martin Kepplinger 2020-07-30 15:14 ` Alan Stern
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=60150284-be13-d373-5448-651b72a7c4c9@puri.sm \ --to=martin.kepplinger@puri.sm \ --cc=James.Bottomley@hansenpartnership.com \ --cc=bvanassche@acm.org \ --cc=cang@codeaurora.org \ --cc=kernel@puri.sm \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-scsi@vger.kernel.org \ --cc=martin.petersen@oracle.com \ --cc=stern@rowland.harvard.edu \ --subject='Re: [PATCH] scsi: sd: add runtime pm to open / release' \ /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
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.