Messages in this thread | | | Date | Mon, 4 Aug 2008 22:01:23 +0200 | From | "Dmitry Adamushko" <> | Subject | Re: [rfc-patch, bugfix] x86-microcode |
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2008/8/4 Max Krasnyansky <maxk@qualcomm.com>: > Dmitry Adamushko wrote: >> Hi, >> >> >> [ consider it a pre-release and RFC... I'm a bit in hurry now and just send what I have got by this moment. >> Although, I expect it to be workable ] >> >> >> this change is supposed to fix bug#11197 (note, its name "Oops in microcode sysfs registration" is misleading) >> >> The problem description can be found here: >> http://www.ussg.iu.edu/hypermail/linux/kernel/0807.3/3791.html >> or >> http://lkml.org/lkml/2008/7/24/260 >> >> perhaps it does look quite bulky for -rc, although it's mainly move-redesign-some-bits of the code and >> I tried to preserve the original logic (even if it looked like a possible optimizations might had been applied) >> as much as possible. >> >> The basic idea is that we introduce another mechanism to run ucode-updates on a target cpu >> and replace set_cpus_allowed_ptr() in (1) cpu-hotplug events and (2) module load. >> >> >> [1/2] x86-microcode: generic updates >> >> Basically, it introduces microcode_update_cpu() which can be run either from start_secondary() >> (perhaps via a function pointer) or scheduled via keventd ([2/2]) and reworks the logic of cpu-hotplug events. >> >> [2/2] x86-microcode: do updates via workqueue > > Looks good to me. You did not change the old interface which still does > set_cpus_allowed_ptr() (ie racy against sched_setaffinity())
ah, right. I've only fixed reload_store() vs. cpu_down().
sched_setaffinity() calls get_online_cpus() so a pair of cpu_maps_update_begin() + cpu_hotplug_begin() would need to be used by the following code:
old_mask = p->cpus_allowed; set_cpus_allowed_ptr(p, new_mask); // do_something set_cpus_allowed_ptr(p, old_mask);
or we'd introduce another mutex to be used in both cases... but I think we just can get rid of most of use-cases (if not all) by replacing them with schedule_work_on().
> > Max >
-- Best regards, Dmitry Adamushko
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