Commit 9dd04ec6 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: intel_pstate: Always read hwp_cap_cached with READ_ONCE() 



Because intel_pstate_get_hwp_max() which updates hwp_cap_cached
may run in parallel with the readers of it, annotate all of the
read accesses to it with READ_ONCE().

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarChen Yu <yu.c.chen@intel.com>
parent 7c53f6b6

drivers/cpufreq/intel_pstate.c

+7 −6
Original line number Diff line number Diff line
@@ -914,7 +914,7 @@ static void intel_pstate_hwp_offline(struct cpudata *cpu) 
	}



	value &= ~GENMASK_ULL(31, 0);

	min_perf = HWP_LOWEST_PERF(cpu->hwp_cap_cached);

	min_perf = HWP_LOWEST_PERF(READ_ONCE(cpu->hwp_cap_cached));



	/* Set hwp_max = hwp_min */

	value |= HWP_MAX_PERF(min_perf);
@@ -1750,6 +1750,7 @@ static int hwp_boost_hold_time_ns = 3 * NSEC_PER_MSEC; 
static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu)

{

	u64 hwp_req = READ_ONCE(cpu->hwp_req_cached);

	u64 hwp_cap = READ_ONCE(cpu->hwp_cap_cached);

	u32 max_limit = (hwp_req & 0xff00) >> 8;

	u32 min_limit = (hwp_req & 0xff);

	u32 boost_level1;
@@ -1776,14 +1777,14 @@ static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu) 
		cpu->hwp_boost_min = min_limit;



	/* level at half way mark between min and guranteed */

	boost_level1 = (HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) + min_limit) >> 1;

	boost_level1 = (HWP_GUARANTEED_PERF(hwp_cap) + min_limit) >> 1;



	if (cpu->hwp_boost_min < boost_level1)

		cpu->hwp_boost_min = boost_level1;

	else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(cpu->hwp_cap_cached))

		cpu->hwp_boost_min = HWP_GUARANTEED_PERF(cpu->hwp_cap_cached);

	else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) &&

		 max_limit != HWP_GUARANTEED_PERF(cpu->hwp_cap_cached))

	else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(hwp_cap))

		cpu->hwp_boost_min = HWP_GUARANTEED_PERF(hwp_cap);

	else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(hwp_cap) &&

		 max_limit != HWP_GUARANTEED_PERF(hwp_cap))

		cpu->hwp_boost_min = max_limit;

	else

		return;