| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <534818EB.3080406@semaphore.gr>
Date: Fri, 11 Apr 2014 19:31:39 +0300
From: Stratos Karafotis <stratosk@...aphore.gr>
To: Viresh Kumar <viresh.kumar@...aro.org>
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 11/04/2014 07:24 πμ, Viresh Kumar wrote:
> 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.
Of course, you are right!
Yes, I partially tested it. But my frequency table didn't contain an
invalid entry. I will fix it.
> 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
OK, I will do it. I was thinking about performance but as you mentioned
20 copies are too much. :)
>> + 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 :)
>
I will prepare the patches with your suggestions.
Thank you very much for your review!
Stratos
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists