linux-kernel - Re: [Xen-devel] [PATCH 1/2] xenbus: don't bail early from xenbus_dev_request_and

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Date:	Thu, 07 Jul 2016 06:09:32 -0600
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<david.vrabel@...rix.com>
Cc:	<xen-devel@...ts.xenproject.org>, <boris.ostrovsky@...cle.com>,
	"Juergen Gross" <JGross@...e.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 1/2] xenbus: don't bail early from
 xenbus_dev_request_and_reply()

>>> On 07.07.16 at 13:36, <david.vrabel@...rix.com> wrote:
> On 07/07/16 08:32, Jan Beulich wrote:
>> We must not skip the transaction_end() call for a failed
>> XS_TRANSACTION_START. The removed code fragment got introduced by
>> commit 027bd7e899 ("xen/xenbus: Avoid synchronous wait on XenBus
>> stalling shutdown/restart") without its description really indicating
>> why it was added (and hence I can't identify whether a more complex
>> change might be needed here).
> 
> If sending the XS_TRANSACTION_END message failed, then the transaction
> is still open and transaction_end() should not be called.
> 
> However, if sending an XS_TRANSACTION_START failed, then
> transaction_end() should be called.
> 
> So, yes a more complex fix is needed here.

Well, both of the things you name are what happens with the patch
in place. So if those two conditions are all that needs to be satisfied,
then no more complex change is needed afaict (and was the behavior
before the cross referenced commit) - the question really is whether
that other commit meant to deal with something _beyond_ those two
things.

Jan