Hello everyone, Exception handlers which may run on IST stack disable and enable preemption twice. For example do_int3() [1]. This one calls ist_enter() which disables preemption with preempt_disable() every time without any conditions. And later do_int3() calls preempt_disable() again [2] before do_trap().
Of course we decrement preemption counter in the end of such exception handlers twice too. But what's actual purpose of doing this two times? [1] https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/arch/x86/kernel/traps.c?id=refs/tags/next-20161117#n530 [2] https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/arch/x86/kernel/traps.c?id=refs/tags/next-20161117#n566 Thank you.
