Bug 31790

Summary:	Retry on EIO on opening /dev/console
Product:	ConsoleKit	Reporter:	Martin Pitt <martin.pitt>
Component:	Daemon	Assignee:	william.jon.mccann
Status:	NEW ---	QA Contact:
Severity:	normal
Priority:	medium	CC:	cjwatson
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	git formatted patch

Description Martin Pitt 2010-11-20 09:01:58 UTC

As reported in https://launchpad.net/bugs/544139, ConsoleKit sometimes fails to track the active VT. This particular case was tracked down to a race condition that happens if you try to open /dev/console while the current TTY is currently being closed. This yields an -EIO error, in which case CK should just try again.

For a more detailled summary of the problem from a kernel perspective, please see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245 .

We have carried this patch for some months now and also backported it to previous stable releases. It was confirmed to fix the problem and we didn't get any negative feedback about it.

Comment 1 Martin Pitt 2010-11-20 09:04:40 UTC

Created attachment 40437 [details] [review]
git formatted patch

Patch by Colin Watson.

Comment 2 Lennart Poettering 2011-02-16 15:47:05 UTC

Grrr, sleep loops are evil. I wonder if we should just ignore this bug until the BKL is gone. Seems the issue is gone on .38 anyway.

Comment 3 Lennart Poettering 2011-02-18 05:05:53 UTC

Hmm, so I have discussed this with some folks, and it seems we do need something like this as the kernel will not help us here.

However, I don't think the patch is acceptable: there are other reasons why EIO might be returned. Since we cannot distuingish the error causes we need at least a safe way out. My suggestion would be to retry opening 20 times and then give up. In systemd I have settled to use 20 times with 50ms in between, totalling to 1s in total.

Could you please update the patch? I'll then merge it.

Comment 4 Lennart Poettering 2011-05-02 17:21:09 UTC

OK, I merged the patch now nonetheless. We should get fixed this properly one day (i.e. only retry a max number), so leaving this bug open.

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