Messages in this thread | | | From | Yuri Norov <> | Subject | Re: [PATCH 3/6] bitmap_parselist: rework input string parser | Date | Tue, 26 Mar 2019 21:09:18 +0000 |
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+ 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, 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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