Re: [PATCH] signals: check_kill_permission: don't check creds if same_thread_group()

From: David Howells
Date: Tue May 18 2010 - 09:52:49 EST


Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> Yes, but both current_cred() and same_thread_group(current, t) call
> get_current(), and gcc doesn't cache the result because we call
> audit_signal_info() in between.

Sorry, yes. I was reading get_current() as current_cred() for some reason.

However, you are _still_ calling get_current() twice... So that bit of your
changelog isn't really correct.

In fact, get_current() should be __attribute_const__ since it can't change
whilst you're looking at it, except within switch_to(), probably in a piece of
assembly code, so gcc should be free to cache it as long as it likes.

David
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