Commit 592e2545 authored Nov 03, 2017 by Jan Kara Committed by Dan Williams Nov 03, 2017

mm: Handle 0 flags in _calc_vm_trans() macro



_calc_vm_trans() does not handle the situation when some of the passed
flags are 0 (which can happen if these VM flags do not make sense for
the architecture). Improve the _calc_vm_trans() macro to return 0 in
such situation. Since all passed flags are constant, this does not add
any runtime overhead.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

parent 8a5776a5

include/linux/mman.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -63,8 +63,9 @@ static inline bool arch_validate_prot(unsigned long prot)
		* ("bit1" and "bit2" must be single bits)
		*/
		#define _calc_vm_trans(x, bit1, bit2) \
		((!(bit1) \|\| !(bit2)) ? 0 : \
		((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
		: ((x) & (bit1)) / ((bit1) / (bit2)))
		: ((x) & (bit1)) / ((bit1) / (bit2))))

		/*
		* Combine the mmap "prot" argument into "vm_flags" used internally.

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