Messages in this thread | | | Date | Mon, 14 Mar 2016 13:45:36 +0900 | From | Byungchul Park <> | Subject | Re: [PATCH v6 1/2] printk: Factor out buffering and irq work queuing in printk_deferred |
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On Mon, Mar 14, 2016 at 10:21:57AM +0900, Sergey Senozhatsky wrote: > Hello Byungchul, > > Sorry, I'll make sure I Cc you next time. Jan Kara's updated patch set > > http://marc.info/?l=linux-kernel&m=145787625506342
Hello Sergey,
It would be appreciated if you or Jan Cc me from now.
> > it's quite close to what you have done in this patch, but Jan's > patch also solves a number of more likely to happen cases. > > have time to take a look?
I checked it now. I hope it will be accepted, then I can work mine based on the Jan's patch.
> > the lock debug patch in your series is different. can we settle > down async printk first and then return to it? it's not so simple... > > > On (03/11/16 19:37), Byungchul Park wrote: > [..] > > int printk_deferred(const char *fmt, ...) > > { > > va_list args; > > int r; > > > > preempt_disable(); > > + > > va_start(args, fmt); > > - r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); > > + r = vprintk_deferred(fmt, args); > > va_end(args); > > + printk_pending_output(); > > > > - __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); > > - irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); > > preempt_enable(); > > > > return r; > > vprintk_deferred() does vprintk_emit()->{spin_lock()} again? cosole_lock() is > moved out of sight, but logbug_lock is still there. wouldn't this (in the worst
We have to ensure the critical section by logbug_lock will not call printk() or try to obtain the lock again. Current code works well in those regards. logbuf_lock is not the thing we have to care when considering the problem this patch deal with.
What do you think?
> case) result in endless loop after all? sorry if I'm missing something.
As long as we ensure it, the endless loop by logbuf_lock cannot happen.
> > -ss
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