From: Martin Kepplinger <martin.kepplinger@puri.sm> To: James Bottomley <James.Bottomley@HansenPartnership.com>, Alan Stern <stern@rowland.harvard.edu> Cc: 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: Thu, 30 Jul 2020 10:52:14 +0200 [thread overview] Message-ID: <d3fe36a9-b785-a5c4-c90d-b8fa10f4272f@puri.sm> (raw) In-Reply-To: <1596047349.4356.84.camel@HansenPartnership.com> On 29.07.20 20:29, James Bottomley wrote: > On Wed, 2020-07-29 at 14:25 -0400, Alan Stern wrote: >> On Wed, Jul 29, 2020 at 06:43:48PM +0200, Martin Kepplinger wrote: > [...] >>>>> --- a/drivers/scsi/scsi_error.c >>>>> +++ b/drivers/scsi/scsi_error.c >>>>> @@ -554,16 +554,8 @@ int scsi_check_sense(struct scsi_cmnd >>>>> *scmd) >>>>> * so that we can deal with it there. >>>>> */ >>>>> if (scmd->device->expecting_cc_ua) { >>>>> - /* >>>>> - * Because some device does not queue >>>>> unit >>>>> - * attentions correctly, we carefully >>>>> check >>>>> - * additional sense code and qualifier >>>>> so as >>>>> - * not to squash media change unit >>>>> attention. >>>>> - */ >>>>> - if (sshdr.asc != 0x28 || sshdr.ascq != >>>>> 0x00) >>>>> { >>>>> - scmd->device->expecting_cc_ua = >>>>> 0; >>>>> - return NEEDS_RETRY; >>>>> - } >>>>> + scmd->device->expecting_cc_ua = 0; >>>>> + return NEEDS_RETRY; >>>> >>>> Well, yes, but you can't do this because it would lose us media >>>> change events in the non-suspend/resume case which we really >>>> don't want. That's why I was suggesting a new flag. >>>> >>>> James >>> >>> also if I set expecting_cc_ua in resume() only, like I did? >> >> That wouldn't make any difference. The information sent by your >> card reader has sshdr.asc == 0x28 and sshdr.ascq == 0x00 (you can see >> it in the log). So because of the code here in scsi_check_sense(), >> which you can't change, the Unit Attention sent by the card reader >> would not be retried even if you do set the flag in resume(). > > But if we had a new flag, like expecting_media_change, you could set > that in resume and we could condition the above test in the code on it > and reset it and do a retry if it gets set. I'm not saying we have to > do it this way, but it sounds like we have to do something in the > kernel, so I think the flag will become necessary but there might be a > bit of policy based dance around how it gets set in the kernel (to > avoid losing accurate media change events). > > James > Maybe I should just start a new discussion with a patch, but the below is what makes sense to me (when I understand you correctly) and seems to work. I basically add a new flag, so that the old flags behave unchanged and only call it during *runtime* resume for SD cards: --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -553,15 +553,21 @@ int scsi_check_sense(struct scsi_cmnd *scmd) * information that we should pass up to the upper-level driver * so that we can deal with it there. */ - if (scmd->device->expecting_cc_ua) { + if (scmd->device->expecting_cc_ua || + scmd->device->expecting_media_change) { /* * Because some device does not queue unit * attentions correctly, we carefully check * additional sense code and qualifier so as - * not to squash media change unit attention. + * not to squash media change unit attention; + * unless expecting_media_change is set, indicating + * that the media (most likely) didn't change + * but a device only believes so (for example + * because of suspend/resume). */ - if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) { - scmd->device->expecting_cc_ua = 0; + if ((sshdr.asc != 0x28 || sshdr.ascq != 0x00) || + scmd->device->expecting_media_change) { + scmd->device->expecting_media_change = 0; return NEEDS_RETRY; } } diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index d90fefffe31b..b647fab2b663 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -114,6 +114,7 @@ static void sd_shutdown(struct device *); static int sd_suspend_system(struct device *); static int sd_suspend_runtime(struct device *); static int sd_resume(struct device *); +static int sd_resume_runtime(struct device *); static void sd_rescan(struct device *); static blk_status_t sd_init_command(struct scsi_cmnd *SCpnt); static void sd_uninit_command(struct scsi_cmnd *SCpnt); @@ -574,7 +575,7 @@ static const struct dev_pm_ops sd_pm_ops = { .poweroff = sd_suspend_system, .restore = sd_resume, .runtime_suspend = sd_suspend_runtime, - .runtime_resume = sd_resume, + .runtime_resume = sd_resume_runtime, }; static struct scsi_driver sd_template = { @@ -3652,6 +3653,21 @@ static int sd_resume(struct device *dev) return ret; } +static int sd_resume_runtime(struct device *dev) +{ + struct scsi_disk *sdkp = dev_get_drvdata(dev); + + /* Some SD cardreaders report media change when resuming from suspend + * because they can't keep track during suspend. */ + + /* XXX This is not unproblematic though: We won't notice when a card + * was really changed during runtime suspend! We basically rely on users + * to unmount or suspend before doing so. */ + sdkp->device->expecting_media_change = 1; + + return sd_resume(dev); +} + /** * init_sd - entry point for this driver (both when built in or when * a module). diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index bc5909033d13..8c8f053f71c8 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -169,6 +169,8 @@ 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; /* Expecting media change ASC/ASCQ + when it actually doesn't change */ 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:[~2020-07-30 8:52 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 [this message] 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 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
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