+ Mike Travis <[email protected]> + Thomas Gleixner <[email protected]>
---------------------------------------------------------------------- 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
