Messages in this thread | | | Date | Fri, 25 Nov 2016 16:17:24 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCHv4 6/6] printk: remove zap_locks() function |
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On Fri, Nov 25, 2016 at 04:01:13PM +0100, Petr Mladek wrote: > On Fri 2016-10-28 00:49:33, Sergey Senozhatsky wrote: > > 2) Since commit cf9b1106c81c ("printk/nmi: flush NMI messages on the > > system panic") panic attempts to zap the `logbuf_lock' spin_lock to > > successfully flush nmi messages to `logbuf'. > > Note that the same code is newly used to flush also the printk_safe > per-CPU buffers. It means that logbuf_lock is zapped also when > flushing these new buffers. >
Note that (raw_)spin_lock_init() as done here and in printk_nmi_flush_on_panic() can wreck the lock state and doesn't ensure a subsequent spin_lock() of said lock will actually work.
The very best solution is to simply ignore the lock in panic situations rather than trying to wreck it.
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