From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D3BEC433E3 for ; Thu, 30 Jul 2020 08:52:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECA3C21744 for ; Thu, 30 Jul 2020 08:52:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728732AbgG3Iwx (ORCPT ); Thu, 30 Jul 2020 04:52:53 -0400 Received: from comms.puri.sm ([159.203.221.185]:54804 "EHLO comms.puri.sm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726273AbgG3Iwv (ORCPT ); Thu, 30 Jul 2020 04:52:51 -0400 Received: from localhost (localhost [127.0.0.1]) by comms.puri.sm (Postfix) with ESMTP id D98EFE03D2; Thu, 30 Jul 2020 01:52:20 -0700 (PDT) Received: from comms.puri.sm ([127.0.0.1]) by localhost (comms.puri.sm [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3-zm5usp4V4V; Thu, 30 Jul 2020 01:52:20 -0700 (PDT) Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release To: James Bottomley , Alan Stern Cc: Bart Van Assche , Can Guo , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@puri.sm References: <20200706164135.GE704149@rowland.harvard.edu> <20200728200243.GA1511887@rowland.harvard.edu> <20200729143213.GC1530967@rowland.harvard.edu> <1596033995.4356.15.camel@linux.ibm.com> <1596034432.4356.19.camel@HansenPartnership.com> <1596037482.4356.37.camel@HansenPartnership.com> <20200729182515.GB1580638@rowland.harvard.edu> <1596047349.4356.84.camel@HansenPartnership.com> From: Martin Kepplinger Autocrypt: addr=martin.kepplinger@puri.sm; keydata= mQINBFULfZABEADRxJqDOYAHfrp1w8Egcv88qoru37k1x0Ugy8S6qYtKLAAt7boZW+q5gPv3 Sj2KjfkWA7gotXpASN21OIfE/puKGwhDLAySY1DGNMQ0gIVakUO0ji5GJPjeB9JlmN5hbA87 Si9k3yKQQfv7Cf9Lr1iZaV4A4yjLP/JQMImaCVdC5KyqJ98Luwci1GbsLIGX3EEjfg1+MceO dnJTKZpBAKd1J7S2Ib3dRwvALdiD7zqMGqkw5xrtwasatS7pc6o/BFgA9GxbeIzKmvW/hc3Q amS/sB12BojyzdUJ3TnIoAqvwKTGcv5VYo2Z+3FV+/MJVXPo8cj2vmfxQx1WG4n6X0pK4X8A BkCKw2N/evMZblNqAzzGVtoJvqQYkzQ20Fm+d3wFl6lS1db4MB+kU13G8kEIE22Q3i6kx4NA N49FLlPeDabGfJUyDaZp5pmKdcd7/FIGH/HjShjx7g+LKSwWNMkDygr4WARAP4h8zYDZuNqe ofPvMLqJxHeexBPIGF/+OwMyTvM7otP5ODuFmq6OqjNPf1irJmkiFv3yEa+Ip0vZzwl4XvrZ U0IKjSy2rbRLg22NsJT0XVZJbutIXYSvIHGqSxzzfiOOLnRjR++fbeEoVlRJ4NZHDKCh3pJv LNd+j03jXr4Rm058YLgO7164yr7FhMZniBJw6z648rk8/8gGPQARAQABtC1NYXJ0aW4gS2Vw cGxpbmdlciA8bWFydGluLmtlcHBsaW5nZXJAcHVyaS5zbT6JAk4EEwEIADgWIQTyCCuID55C OTRobj9QA5jfWrOH0wUCXPSlkwIbAwULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRBQA5jf 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linux-scsi@vger.kernel.org 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 */