Re: [Xen-devel] [PATCH] xenconsole: merge pty access check into when it is opened

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/12/13 11:51, Ian Jackson wrote:
> Andrew Cooper writes ("Re: [Xen-devel] [PATCH] xenconsole: merge pty access 
> check into when it is opened"):
>> On 01/12/2013 23:14, Matthew Daley wrote:
>>> On Mon, Dec 2, 2013 at 12:41 AM, Andrew Cooper
>>> <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> access() can fail for many more reasons than just EACCES.  I would skip
>>>> the errno check entirely and always print the error.
>>> err() doesn't return though (calls exit()). Given that, is always
>>> calling it still acceptable?
> ...
>> Even as the patch currently stands, the behaviour of the loop has
>> changed. Before, it would eat any error from access(), and only die in
>> the toctou case where open() subsequently failed.
> I had the impression there is sometimes a race during domain startup,
> between a toolstack invoking xenconsole and xenconsoled allocating the
> pty.
>
> Ian.

In which case the xenstore path should be NULL and we wander around loop
and wait on the watch again.

~Andrew



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