Messages in this thread | | | Subject | Re: [PATCH 3/6] bitmap_parselist: rework input string parser | From | Mike Travis <> | Date | Tue, 26 Mar 2019 14:58:45 -0700 |
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On 3/26/2019 2:09 PM, Yuri Norov wrote: > + Mike Travis <travis@sgi.com> > + Thomas Gleixner <tglx@linutronix.de> > > ---------------------------------------------------------------------- > On Tue, Mar 26, 2019 at 12:07:45AM +0300, Yury Norov wrote: >>> The requirement for this rework is to keep the __bitmap_parselist() >>> copy-less and single-pass but make it more readable and maintainable by >>> splitting into logical parts and removing explicit nested cycles and >>> opaque local variables. >>> >>> __bitmap_parselist() can parse userspace inputs and therefore we cannot >>> use simple_strtoul() to parse numbers. > >> So, all above depends to what memory we access kernel / user space. >> Perhaps we can get copy of memory of a given size and then parse it in kernel space always? > >> -- >> With Best Regards, >> Andy Shevchenko > > What I missed during rework is that we have only one caller of *parselist_user - > it's write_irq_affinity() introduced by Mike Travis in kernel/irq/proc.c. It doesn't look > like a hot path as it's file operations handler. If no objections from Mike or Thomas,
No objections from me as long as you can still change irq affinity using a cpulist instead of a cpumask.
Thanks, Mike Travis
> I think it would make sense to copy_from_user() the userspace data at the beginning > in sake of simplicity of __bitmap_parselist(), as you suggested above. > > Yury >
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