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Date:   Sat, 10 Jun 2023 08:03:59 -0700
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Subject: Re: Fwd: Waking up from resume locks up on sr device
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To:     Bagas Sanjaya <bagasdotme@gmail.com>, Pavel Machek <pavel@ucw.cz>,
        Damien Le Moal <dlemoal@kernel.org>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <len.brown@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kees Cook <keescook@chromium.org>,
        Tony Luck <tony.luck@intel.com>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Thorsten Leemhuis <linux@leemhuis.info>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Phillip Potter <phil@philpotter.co.uk>,
        Joe Breuer <linux-kernel@jmbreuer.net>,
        Linux Power Management <linux-pm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Hardening <linux-hardening@vger.kernel.org>,
        Linux Regressions <regressions@lists.linux.dev>,
        Linux SCSI <linux-scsi@vger.kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        Dan Williams <dan.j.williams@intel.com>,
        Hannes Reinecke <hare@suse.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Martin Kepplinger <martin.kepplinger@puri.sm>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>
References: <2d1fdf6d-682c-a18d-2260-5c5ee7097f7d@gmail.com>
 <5513e29d-955a-f795-21d6-ec02a2e2e128@gmail.com>
 <ZIQ6bkau3j6qGef8@duo.ucw.cz>
 <07d6e2e7-a50a-8cf4-5c5d-200551bd6687@gmail.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <07d6e2e7-a50a-8cf4-5c5d-200551bd6687@gmail.com>
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On 6/10/23 06:27, Bagas Sanjaya wrote:
> On 6/10/23 15:55, Pavel Machek wrote:
>>>> #regzbot introduced: v5.0..v6.4-rc5 https://bugzilla.kernel.org/show_bug.cgi?id=217530
>>>> #regzbot title: Waking up from resume locks up on SCSI CD/DVD drive
>>>>
>>> The reporter had found the culprit (via bisection), so:
>>>
>>> #regzbot introduced: a19a93e4c6a98c
>> Maybe cc the authors of that commit?
> 
> Ah! I forgot to do that! Thanks anyway.

Hi Damien,

Why does the ATA code call scsi_rescan_device() before system resume has
finished? Would ATA devices still work with the patch below applied?

Thanks,

Bart.


diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6a959c993dd8..be3971b7fd27 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1629,6 +1629,20 @@ void scsi_rescan_device(struct device *dev)
  {
  	struct scsi_device *sdev = to_scsi_device(dev);

+#ifdef CONFIG_PM_SLEEP
+	/*
+	 * The ATA subsystem may call scsi_rescan_device() before resuming has
+	 * finished. If this happens, prevent a deadlock on the device_lock()
+	 * call by skipping rescanning.
+	 */
+	if (dev->power.is_suspended)
+		return;
+#endif
+
+	/*
+	 * Serialize scsi_driver.rescan() calls and scsi_driver.gendrv.remove()
+	 * calls.
+	 */
  	device_lock(dev);

  	scsi_attach_vpd(sdev);