Re: valid task structure and wake_up_process

On 4/14/08, Arjan van de Ven <arjan@xxxxxxxxxxxxx> wrote:
On Mon, 14 Apr 2008 13:36:42 -0500
"Shirish Pargaonkar" <shirishpargaonkar@xxxxxxxxx> wrote:

How do I check whether a task is valid before calling
wake_up_process() with that task structure pointer?

Hi,

how did you get the pointer you got?

That part (the guy who gave you the pointer) should have taken a reference on the task basically,
or otherwise locked against the task going away.

In giving you advice it would help tremendously if you actually posted your code...





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Thanks.

This is cifs code fs/cifs.

In cifs_demultiplex_thread, in fs/cifs/connect.c, it calls wake_up_process in
a thread cifsd.

The task struct ptr is stored in mid as current when sending a request. So this
could a command such as ls or some other application.
A request was sent but a reply was not received or reply was processed late
before the process went away and we have a probably freed task structure
being treated as valid in cifs_demultiplex_thread.

So I thought of checking validity of task structure before calling
wake_up_process.

Regards,

Shirish
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