Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [PATCH v1 4/5] cpufreq: intel_pstate: Get rid of unnecessary READ_ONCE() annotations | Date | Thu, 21 Mar 2024 20:33:02 +0100 |
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Drop a redundant check involving READ_ONCE() from notify_hwp_interrupt() and make it check hwp_active without READ_ONCE() which is not necessary, because that variable is only set once during the early initialization of the driver.
In order to make that clear, annotate hwp_active with __ro_after_init.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> --- drivers/cpufreq/intel_pstate.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-)
Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -292,7 +292,7 @@ struct pstate_funcs { static struct pstate_funcs pstate_funcs __read_mostly; -static int hwp_active __read_mostly; +static bool hwp_active __ro_after_init; static int hwp_mode_bdw __read_mostly; static bool per_cpu_limits __read_mostly; static bool hwp_boost __read_mostly; @@ -1640,7 +1640,7 @@ void notify_hwp_interrupt(void) unsigned long flags; u64 value; - if (!READ_ONCE(hwp_active) || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) + if (!hwp_active || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) return; rdmsrl_safe(MSR_HWP_STATUS, &value); @@ -1653,14 +1653,6 @@ void notify_hwp_interrupt(void) goto ack_intr; /* - * Currently we never free all_cpu_data. And we can't reach here - * without this allocated. But for safety for future changes, added - * check. - */ - if (unlikely(!READ_ONCE(all_cpu_data))) - goto ack_intr; - - /* * The free is done during cleanup, when cpufreq registry is failed. * We wouldn't be here if it fails on init or switch status. But for * future changes, added check. @@ -3464,7 +3456,7 @@ static int __init intel_pstate_init(void * deal with it. */ if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || hwp_forced) { - WRITE_ONCE(hwp_active, 1); + hwp_active = true; hwp_mode_bdw = id->driver_data; intel_pstate.attr = hwp_cpufreq_attrs; intel_cpufreq.attr = hwp_cpufreq_attrs;
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