Hi,
looking at your last patch I noticed something.
I think it fails to work if we hit a peculiar race condition.
It looks to me like we can get the following:
task A
pre_reset()
--> calling scsi_block_requests()
task B
shutdown()
--> setting the shutdown flag
post_reset()
--> checking the flag -> do nothing -> deadlock
So we need in addition something like the below patch.
What do you think?
Regards
Oliver
>From 68cc8940d7dde8e2a48217d8086cd692809e7980 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <[email protected]>
Date: Mon, 15 Jan 2018 13:56:59 +0100
Subject: [PATCH] UAS: fix race between post_reset() and shutdown()
Disconnect due to shutdown can happen after pre_reset() has been called. Thus
the host
must be unblocked even in the shutdown case.
Signed-off-by: Oliver Neukum <[email protected]>
---
drivers/usb/storage/uas.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 338133a239df..d5ed1e581fb5 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -1046,10 +1046,11 @@ static int uas_post_reset(struct usb_interface *intf)
struct Scsi_Host *shost = usb_get_intfdata(intf);
struct uas_dev_info *devinfo = (struct uas_dev_info *)shost->hostdata;
unsigned long flags;
- int err;
+ int err = 1;
+ /* We may have lost the race and shutdown after pre_reset() */
if (devinfo->shutdown)
- return 0;
+ goto skip;
err = uas_configure_endpoints(devinfo);
if (err && err != ENODEV)
@@ -1062,6 +1063,7 @@ static int uas_post_reset(struct usb_interface *intf)
scsi_report_bus_reset(shost, 0);
spin_unlock_irqrestore(shost->host_lock, flags);
+skip:
scsi_unblock_requests(shost);
return err ? 1 : 0;
--
2.13.6
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