On 06/07, Eric Paris wrote:

On Tue, 2011-06-07 at 19:19 +0200, Oleg Nesterov wrote:

quoted

With or without this patch, can't we call audit_syscall_exit() twice
if there is something else in _TIF_WORK_SYSCALL_EXIT mask apart from
SYSCALL_AUDIT ? First time it is called from asm, then from
syscall_trace_leave(), no?

For example. The task has TIF_SYSCALL_AUDIT and nothing else, it does
system_call->auditsys->system_call_fastpath. What if it gets, say,
TIF_SYSCALL_TRACE before ret_from_sys_call?

No harm is done calling twice.  The first call will do the real work and
cleanup.  It will set a flag in the audit data that the work has been
done (in_syscall == 0) thus the second call will then not do any real
work and won't have anything to clean up.

Hmm... and I assume context->previous != NULL is not possible on x86_64.
OK, thanks.

And I guess, all CONFIG_AUDITSYSCALL code in entry.S is only needed to
microoptimize the case when TIF_SYSCALL_AUDIT is the only reason for the
slow path. I wonder if it really makes the measureble difference...

Oleg.