Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756283AbbGGKqK (ORCPT ); Tue, 7 Jul 2015 06:46:10 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:36377 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752304AbbGGKp7 (ORCPT ); Tue, 7 Jul 2015 06:45:59 -0400 Date: Tue, 7 Jul 2015 16:15:53 +0530 From: Viresh Kumar To: Pan Xinhui Cc: "linux-kernel@vger.kernel.org" , linux-pm@vger.kernel.org, rjw@rjwysocki.net, "mnipxh@163.com" , "yanmin_zhang@linux.intel.com" Subject: Re: [PATCH] acpi-cpufreq: replace per_cpu with driver_data of policy Message-ID: <20150707104553.GN14598@linux> References: <559BA9FF.7050702@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <559BA9FF.7050702@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7107 Lines: 215 On 07-07-15, 18:29, Pan Xinhui wrote: > > Now policy has field of driver_data, we can use it to get rid of per_cpu > acpi_cpufreq_data. Instead: "Drivers can store their internal per-policy information in policy->driver_data, lets use it." > we have benefits after this replacing. 1) memory saving. 2) policy is s/we/We Also these points can be kept in separate lines :) > shared by several cpus, per_cpu seems not correct. useing *driver_data* using > is more reasonable. 3) fix a memory leak in acpi_cpufreq_cpu_exit. Not just that. You are also fixing NULL pointer dereferences if wrong or uninitialized per-cpu data is used, because of a recent hotplug of policy->cpu. > as > policy->cpu might change after cpu hotplug. So sometimes we cant't free > *data*, use *driver_data* to fix it. 4) fix a zero return value of > get_cur_freq_on_cpu. Only per_cpu(policy->cpu) is set to *data*, if we > try to get cpufreq on other cpus, we get zero instead of correct values. > Use *driver_data* to fix it. > > Signed-off-by: Pan Xinhui > --- > drivers/cpufreq/acpi-cpufreq.c | 38 +++++++++++++++++++++++--------------- > 1 file changed, 23 insertions(+), 15 deletions(-) > > diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c > index 0136dfc..7f662dd 100644 > --- a/drivers/cpufreq/acpi-cpufreq.c > +++ b/drivers/cpufreq/acpi-cpufreq.c > @@ -72,8 +72,6 @@ struct acpi_cpufreq_data { > cpumask_var_t freqdomain_cpus; > }; > > -static DEFINE_PER_CPU(struct acpi_cpufreq_data *, acfreq_data); > - > /* acpi_perf_data is a pointer to percpu data. */ > static struct acpi_processor_performance __percpu *acpi_perf_data; > > @@ -144,7 +142,7 @@ static int _store_boost(int val) > > static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf) > { > - struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu); > + struct acpi_cpufreq_data *data = policy->driver_data; > > return cpufreq_show_cpus(data->freqdomain_cpus, buf); > } > @@ -327,7 +325,8 @@ static void drv_write(struct drv_cmd *cmd) > put_cpu(); > } > > -static u32 get_cur_val(const struct cpumask *mask) > +static u32 get_cur_val(const struct cpumask *mask, > + struct acpi_cpufreq_data *data) Run checkpatch --strict to see some alignment warnings here.. > { > struct acpi_processor_performance *perf; > struct drv_cmd cmd; > @@ -335,7 +334,7 @@ static u32 get_cur_val(const struct cpumask *mask) > if (unlikely(cpumask_empty(mask))) > return 0; > > - switch (per_cpu(acfreq_data, cpumask_first(mask))->cpu_feature) { > + switch (data->cpu_feature) { > case SYSTEM_INTEL_MSR_CAPABLE: > cmd.type = SYSTEM_INTEL_MSR_CAPABLE; > cmd.addr.msr.reg = MSR_IA32_PERF_CTL; > @@ -346,7 +345,7 @@ static u32 get_cur_val(const struct cpumask *mask) > break; > case SYSTEM_IO_CAPABLE: > cmd.type = SYSTEM_IO_CAPABLE; > - perf = per_cpu(acfreq_data, cpumask_first(mask))->acpi_data; > + perf = data->acpi_data; > cmd.addr.io.port = perf->control_register.address; > cmd.addr.io.bit_width = perf->control_register.bit_width; > break; > @@ -364,19 +363,26 @@ static u32 get_cur_val(const struct cpumask *mask) > > static unsigned int get_cur_freq_on_cpu(unsigned int cpu) > { > - struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu); > + struct acpi_cpufreq_data *data; > + struct cpufreq_policy *policy; > unsigned int freq; > unsigned int cached_freq; > > pr_debug("get_cur_freq_on_cpu (%d)\n", cpu); > > + policy = cpufreq_cpu_get(cpu); > + if (unlikely(!policy)) > + return 0; > + > + data = policy->driver_data; Do + cpufreq_cpu_put(policy); right here. No need of doing this towards the end. > if (unlikely(data == NULL || > data->acpi_data == NULL || data->freq_table == NULL)) { Maybe this if you like: if (unlikely(! data || !data->acpi_data || !data->freq_table)) return 0; > + cpufreq_cpu_put(policy); > return 0; > } > > cached_freq = data->freq_table[data->acpi_data->state].frequency; And this freq_table thing gives you opportunity to write another patch :) policy already have: policy->freq_table :) > - freq = extract_freq(get_cur_val(cpumask_of(cpu)), data); > + freq = extract_freq(get_cur_val(cpumask_of(cpu), data), data); > if (freq != cached_freq) { > /* > * The dreaded BIOS frequency change behind our back. > @@ -385,6 +391,8 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu) > data->resume = 1; > } > > + cpufreq_cpu_put(policy); > + > pr_debug("cur freq = %u\n", freq); > > return freq; > @@ -397,7 +405,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq, > unsigned int i; > > for (i = 0; i < 100; i++) { > - cur_freq = extract_freq(get_cur_val(mask), data); > + cur_freq = extract_freq(get_cur_val(mask, data), data); > if (cur_freq == freq) > return 1; > udelay(10); > @@ -408,7 +416,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq, > static int acpi_cpufreq_target(struct cpufreq_policy *policy, > unsigned int index) > { > - struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu); > + struct acpi_cpufreq_data *data = policy->driver_data; > struct acpi_processor_performance *perf; > struct drv_cmd cmd; > unsigned int next_perf_state = 0; /* Index into perf table */ > @@ -673,7 +681,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) > } > > data->acpi_data = per_cpu_ptr(acpi_perf_data, cpu); > - per_cpu(acfreq_data, cpu) = data; > + policy->driver_data = data; > > if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) > acpi_cpufreq_driver.flags |= CPUFREQ_CONST_LOOPS; > @@ -843,19 +851,19 @@ err_free_mask: > free_cpumask_var(data->freqdomain_cpus); > err_free: > kfree(data); > - per_cpu(acfreq_data, cpu) = NULL; > + policy->driver_data = NULL; > > return result; > } > > static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy) > { > - struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu); > + struct acpi_cpufreq_data *data = policy->driver_data; > > pr_debug("acpi_cpufreq_cpu_exit\n"); > > if (data) { > - per_cpu(acfreq_data, policy->cpu) = NULL; > + policy->driver_data = NULL; > acpi_processor_unregister_performance(data->acpi_data, > policy->cpu); > free_cpumask_var(data->freqdomain_cpus); > @@ -868,7 +876,7 @@ static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy) > > static int acpi_cpufreq_resume(struct cpufreq_policy *policy) > { > - struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu); > + struct acpi_cpufreq_data *data = policy->driver_data; > > pr_debug("acpi_cpufreq_resume\n"); Rest looks fine. -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/