Messages in this thread | | | Date | Wed, 30 Sep 2015 13:53:47 +0200 | From | Peter Zijlstra <> | Subject | Re: Re: [V4 PATCH 3/4] kexec: Fix race between panic() and crash_kexec() called directly |
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On Mon, Sep 28, 2015 at 07:08:19AM +0000, 河合英宏 / KAWAI,HIDEHIRO wrote: > > >> kernel/kexec_core.c:899:3: note: in expansion of macro 'atomic_xchg' > > atomic_xchg(&panic_cpu, -1); > > ^ > > I changed to use atomic_xchg() instead of atomic_set() in V3 > because atomic_set() doesn't mean memory barrier. However, > I thought again and there is no need of barrier; there is no > problem if a competitor sees old value of panic_cpu or new one. > So, atomic_set() is sufficient and using it will remove this warning. > > I will resend the fixed version later.
So if you rely on the memory barrier; you should have also put a comment on explaining the ordering requirements.
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