Commit b9f5c38e authored Jan 12, 2026 by Ben Horgan Committed by Catalin Marinas Jan 16, 2026

arm_mpam: Use non-atomic bitops when modifying feature bitmap



In the test__props_mismatch() kunit test we rely on the struct mpam_props
being packed to ensure memcmp doesn't consider packing. Making it packed
reduces the alignment of the features bitmap and so breaks a requirement
for the use of atomics. As we don't rely on the set/clear of these bits
being atomic, just make them non-atomic.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Fixes: 8c90dc68 ("arm_mpam: Probe the hardware features resctrl supports")
Reviewed-by: Gavin Shan <gshan@redhat.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent b5a69c48

drivers/resctrl/mpam_internal.h

+6 −2

Original line number	Diff line number	Diff line
		@@ -200,8 +200,12 @@ struct mpam_props {
		} PACKED_FOR_KUNIT;

		#define mpam_has_feature(_feat, x) test_bit(_feat, (x)->features)
		#define mpam_set_feature(_feat, x) set_bit(_feat, (x)->features)
		#define mpam_clear_feature(_feat, x) clear_bit(_feat, (x)->features)
		/*
		* The non-atomic get/set operations are used because if struct mpam_props is
		* packed, the alignment requirements for atomics aren't met.
		*/
		#define mpam_set_feature(_feat, x) __set_bit(_feat, (x)->features)
		#define mpam_clear_feature(_feat, x) __clear_bit(_feat, (x)->features)

		/* The values for MSMON_CFG_MBWU_FLT.RWBW */
		enum mon_filter_options {