signals: check_kill_permission: don't check creds if same_thread_group()
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From: David Howells on 18 May 2010 05:00 Oleg Nesterov <oleg(a)redhat.com> wrote: > Also, move "cred = current_cred()" down to avoid calling get_current() > twice. I don't see what you mean by this. same_thread_group() doesn't call current_cred(), so why this change? David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: David Howells on 18 May 2010 10:00
Oleg Nesterov <oleg(a)redhat.com> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |