Messages in this thread | | | Date | Tue, 10 Jun 2014 09:57:36 -0700 | Subject | Re: [RFC PATCH 00/11] printk: safe printing in NMI context | From | Linus Torvalds <> |
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On Tue, Jun 10, 2014 at 9:46 AM, Frederic Weisbecker <fweisbec@gmail.com> wrote: > > There is also a big risk that if we push back this bugfix, nobody will actually do > that desired rewrite. > > Lets be crazy and Cc Linus on that.
Quite frankly, I hate seeing something like this:
kernel/printk/printk.c | 1218 +++++++++++++++++++++++++----------
for something that is stupid and broken. Printing from NMI context isn't really supposed to work, and we all *know* it's not supposed to work.
I'd much rather disallow it, and if there is one or two places that really want to print a warning and know that they are in NMI context, have a special workaround just for them, with something that does *not* try to make printk in general work any better.
Dammit, NMI context is special. I absolutely refuse to buy into the broken concept that we should make more stuff work in NMI context. Hell no, we should *not* try to make more crap work in NMI. NMI people should be careful.
Make a trivial "printk_nmi()" wrapper that tries to do a trylock on logbuf_lock, and *maybe* the existing sequence of
if (console_trylock_for_printk()) console_unlock();
then works for actually triggering the printout. But the wrapper should be 15 lines of code for "if possible, try to print things", and *not* a thousand lines of changes.
Linus
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