From 5ab666e09541e64ce2fd73411c3b5b9e4ad334b1 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 27 Jun 2016 23:47:15 +0200 Subject: [PATCH 1/3] intel_pstate: Do not clear utilization update hooks on policy changes intel_pstate_set_policy() is invoked by the cpufreq core during driver initialization, on changes of policy attributes (minimim and maximum frequency, for example) via sysfs and via CPU notifications from the platform firmware. On some platforms the latter may occur relatively often. Commit bb6ab52f2bef (intel_pstate: Do not set utilization update hook too early) made intel_pstate_set_policy() clear the CPU's utilization update hook before updating the policy attributes for it (and set the hook again after doind that), but that involves invoking synchronize_sched() and adds overhead to the CPU notifications mentioned above and to the sched-RCU handling in general. That extra overhead is arguably not necessary, because updating policy attributes when the CPU's utilization update hook is active should not lead to any adverse effects, so drop the clearing of the hook from intel_pstate_set_policy() and make it check if the hook has been set already when attempting to set it. Fixes: bb6ab52f2bef (intel_pstate: Do not set utilization update hook too early) Reported-by: Jisheng Zhang Tested-by: Jisheng Zhang Tested-by: Doug Smythies Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index fe9dc17ea873..1fa1a32928d7 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -1400,6 +1400,9 @@ static void intel_pstate_set_update_util_hook(unsigned int cpu_num) { struct cpudata *cpu = all_cpu_data[cpu_num]; + if (cpu->update_util_set) + return; + /* Prevent intel_pstate_update_util() from using stale data. */ cpu->sample.time = 0; cpufreq_add_update_util_hook(cpu_num, &cpu->update_util, @@ -1440,8 +1443,6 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) if (!policy->cpuinfo.max_freq) return -ENODEV; - intel_pstate_clear_update_util_hook(policy->cpu); - pr_debug("set_policy cpuinfo.max %u policy->max %u\n", policy->cpuinfo.max_freq, policy->max); From ca5eda5d3db6026080cff267459625c87c43e9ab Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 27 Jun 2016 14:50:13 +0900 Subject: [PATCH 2/3] cpufreq: dt: call of_node_put() before error out If of_match_node() fails, this init function bails out without calling of_node_put(). Also change of_node_put(of_root) to of_node_put(np); both of them hold the same pointer, but it seems better to call of_node_put() against the node returned by of_find_node_by_path(). Signed-off-by: Masahiro Yamada Acked-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq-dt-platdev.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c index 3646b143bbf5..0bb44d5b5df4 100644 --- a/drivers/cpufreq/cpufreq-dt-platdev.c +++ b/drivers/cpufreq/cpufreq-dt-platdev.c @@ -79,15 +79,16 @@ static const struct of_device_id machines[] __initconst = { static int __init cpufreq_dt_platdev_init(void) { struct device_node *np = of_find_node_by_path("/"); + const struct of_device_id *match; if (!np) return -ENODEV; - if (!of_match_node(machines, np)) + match = of_match_node(machines, np); + of_node_put(np); + if (!match) return -ENODEV; - of_node_put(of_root); - return PTR_ERR_OR_ZERO(platform_device_register_simple("cpufreq-dt", -1, NULL, 0)); } From 742c87bf27d3b715820da6f8a81d6357adbf18f8 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 28 Jun 2016 03:29:29 +0200 Subject: [PATCH 3/3] cpufreq: Avoid false-positive WARN_ON()s in cpufreq_update_policy() CPU notifications from the firmware coming in when cpufreq is suspended cause cpufreq_update_current_freq() to return 0 which triggers the WARN_ON() in cpufreq_update_policy() for no reason. Avoid that by checking cpufreq_suspended before calling cpufreq_update_current_freq(). Fixes: c9d9c929e674 (cpufreq: Abort cpufreq_update_current_freq() for cpufreq_suspended set) Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Cc: 4.6+ # 4.6+ --- drivers/cpufreq/cpufreq.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 9009295f5134..5617c7087d77 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2261,6 +2261,10 @@ int cpufreq_update_policy(unsigned int cpu) * -> ask driver for current freq and notify governors about a change */ if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { + if (cpufreq_suspended) { + ret = -EAGAIN; + goto unlock; + } new_policy.cur = cpufreq_update_current_freq(policy); if (WARN_ON(!new_policy.cur)) { ret = -EIO;