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Message-ID: <CAKohpo=u9hHtp94A_KLKupi9de+eZYCWQfEdUV-NS+iryH-gHw@mail.gmail.com>
Date: Fri, 11 Apr 2014 09:54:20 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Stratos Karafotis <stratosk@...aphore.gr>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org >> LKML" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] cpufreq: Introduce macros for cpufreq_frequency_table iteration
On 11 April 2014 03:31, Stratos Karafotis <stratosk@...aphore.gr> wrote:
> This patch intoduces 2 macros which can be used for iteration
> over cpufreq_frequency_table:
>
> - cpufreq_for_each_entry: iterate over each entry of the table
> - cpufreq_for_each_valid_entry: iterate over each entry of the
> table that contains a valid frequency.
>
> It should have no functional changes.
>
> Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>
> ---
>
> I found about 20 occurrences in various drivers that these macros
> can be used. I will proceed with the necessary changes if you
> approve something like this.
>
> Thanks in advance for your time,
Thanks for your time and I find it useful enough. So its a yes from
me :)
But, have you tested this yet?
> Stratos Karafotis.
> ---
>
> drivers/cpufreq/freq_table.c | 54 ++++++++++++++++++++------------------------
> include/linux/cpufreq.h | 29 ++++++++++++++++++++++++
> 2 files changed, 53 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
> index 08e7bbc..19bf0c4 100644
> --- a/drivers/cpufreq/freq_table.c
> +++ b/drivers/cpufreq/freq_table.c
> @@ -21,22 +21,18 @@
> int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
> struct cpufreq_frequency_table *table)
> {
> + struct cpufreq_frequency_table *pos;
> unsigned int min_freq = ~0;
> unsigned int max_freq = 0;
> - unsigned int i;
>
> - for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
> - unsigned int freq = table[i].frequency;
> - if (freq == CPUFREQ_ENTRY_INVALID) {
> - pr_debug("table entry %u is invalid, skipping\n", i);
> + cpufreq_for_each_valid_entry(pos, table) {
> + unsigned int freq = pos->frequency;
move the definition part to the top of this routine, we don't need
to create freq for every iteration here. It was bad earlier as well :)
>
> - continue;
> - }
> if (!cpufreq_boost_enabled()
> - && (table[i].flags & CPUFREQ_BOOST_FREQ))
> + && (pos->flags & CPUFREQ_BOOST_FREQ))
> continue;
>
> - pr_debug("table entry %u: %u kHz\n", i, freq);
> + pr_debug("table entry %lu: %u kHz\n", pos - table, freq);
> if (freq < min_freq)
> min_freq = freq;
> if (freq > max_freq)
> @@ -57,7 +53,8 @@ EXPORT_SYMBOL_GPL(cpufreq_frequency_table_cpuinfo);
> int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
> struct cpufreq_frequency_table *table)
> {
> - unsigned int next_larger = ~0, freq, i = 0;
> + struct cpufreq_frequency_table *pos;
> + unsigned int next_larger = ~0, freq;
> bool found = false;
>
> pr_debug("request for verification of policy (%u - %u kHz) for cpu %u\n",
> @@ -65,9 +62,9 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
>
> cpufreq_verify_within_cpu_limits(policy);
>
> - for (; freq = table[i].frequency, freq != CPUFREQ_TABLE_END; i++) {
> - if (freq == CPUFREQ_ENTRY_INVALID)
> - continue;
> + cpufreq_for_each_valid_entry(pos, table) {
> + freq = pos->frequency;
> +
> if ((freq >= policy->min) && (freq <= policy->max)) {
> found = true;
> break;
> @@ -118,7 +115,8 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
> .driver_data = ~0,
> .frequency = 0,
> };
> - unsigned int i;
> + struct cpufreq_frequency_table *pos;
> + unsigned int i = 0;
>
> pr_debug("request for target %u kHz (relation: %u) for cpu %u\n",
> target_freq, relation, policy->cpu);
> @@ -132,10 +130,10 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
> break;
> }
>
> - for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
> - unsigned int freq = table[i].frequency;
> - if (freq == CPUFREQ_ENTRY_INVALID)
> - continue;
> + cpufreq_for_each_valid_entry(pos, table) {
> + unsigned int freq = pos->frequency;
same here.
> +
> + i = pos - table;
> if ((freq < policy->min) || (freq > policy->max))
> continue;
> switch (relation) {
> @@ -184,8 +182,7 @@ EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
> int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
> unsigned int freq)
> {
> - struct cpufreq_frequency_table *table;
> - int i;
> + struct cpufreq_frequency_table *pos, *table;
>
> table = cpufreq_frequency_get_table(policy->cpu);
> if (unlikely(!table)) {
> @@ -193,9 +190,9 @@ int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
> return -ENOENT;
> }
>
> - for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
> - if (table[i].frequency == freq)
> - return i;
> + cpufreq_for_each_entry(pos, table) {
use cpufreq_for_each_valid_entry() here as well.
> + if (pos->frequency == freq)
> + return pos - table;
> }
>
> return -EINVAL;
> @@ -208,16 +205,13 @@ EXPORT_SYMBOL_GPL(cpufreq_frequency_table_get_index);
> static ssize_t show_available_freqs(struct cpufreq_policy *policy, char *buf,
> bool show_boost)
> {
> - unsigned int i = 0;
> ssize_t count = 0;
> - struct cpufreq_frequency_table *table = policy->freq_table;
> + struct cpufreq_frequency_table *pos, *table = policy->freq_table;
>
> if (!table)
> return -ENODEV;
>
> - for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
> - if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
> - continue;
> + cpufreq_for_each_valid_entry(pos, table) {
> /*
> * show_boost = true and driver_data = BOOST freq
> * display BOOST freqs
> @@ -229,10 +223,10 @@ static ssize_t show_available_freqs(struct cpufreq_policy *policy, char *buf,
> * show_boost = false and driver_data != BOOST freq
> * display NON BOOST freqs
> */
> - if (show_boost ^ (table[i].flags & CPUFREQ_BOOST_FREQ))
> + if (show_boost ^ (pos->flags & CPUFREQ_BOOST_FREQ))
> continue;
>
> - count += sprintf(&buf[count], "%d ", table[i].frequency);
> + count += sprintf(&buf[count], "%d ", pos->frequency);
> }
> count += sprintf(&buf[count], "\n");
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 5ae5100..1c221c8 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -468,6 +468,35 @@ struct cpufreq_frequency_table {
> * order */
> };
>
> +static inline bool validate_entry(struct cpufreq_frequency_table *pos)
> +{
> + while (pos->frequency != CPUFREQ_TABLE_END)
> + if (pos->frequency == CPUFREQ_ENTRY_INVALID)
> + pos++;
This is why I asked you if you have tested it or not.
pos is a local variable here and so pos++ wouldn't reflect in the parent
function. But your code will still work as we will check again for the next
INVALID frequency.
Another important thing: This routine is going to be used from a Macro
and so making it inline is very *inefficient*. We are going to use it from
Atleast 20-25 places (as you mentioned) and we definitely aren't looking
to have so many copies of this one :)
So, you should move this to cpufreq.c
> + else
> + return true;
> + return false;
> +}
> +
> +/*
> + * cpufreq_for_each_entry - iterate over a cpufreq_frequency_table
> + * @pos: the cpufreq_frequency_table * to use as a loop cursor.
> + * @table: the cpufreq_frequency_table * to iterate over.
> + */
> +
> +#define cpufreq_for_each_entry(pos, table) \
> + for (pos = table; pos->frequency != CPUFREQ_TABLE_END; pos++)
> +
> +/*
> + * cpufreq_for_each_valid_entry - iterate over a cpufreq_frequency_table
> + * exluding CPUFREQ_ENTRY_INVALID frequencies.
> + * @pos: the cpufreq_frequency_table * to use as a loop cursor.
> + * @table: the cpufreq_frequency_table * to iterate over.
> + */
> +
> +#define cpufreq_for_each_valid_entry(pos, table) \
> + for (pos = table; validate_entry(pos); pos++)
> +
> int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
> struct cpufreq_frequency_table *table);
Otherwise looks fine. Please update all drivers as well :)
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