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SubjectRe: [PATCH] PM / devfreq: Add debugfs support with devfreq_summary file
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Hi Nathan,

On 12/30/19 12:26 PM, Nathan Chancellor wrote:
> Hi Chanwoo,
>
> On Thu, Dec 26, 2019 at 03:07:49PM +0900, Chanwoo Choi wrote:
>> Add debugfs interface to provide debugging information of devfreq device.
>> It contains 'devfreq_summary' entry to show the summary of registered
>> devfreq devices as following: And the additional debugfs file will be added.
>> - /sys/kernel/debug/devfreq/devfreq_summary
>>
>> [For example on Exynos5422-based Odroid-XU3 board]
>> - In order to show the multiple governors on devfreq_summay result,
>> change the governor of devfreq0 from simple_ondemand to userspace.
>>
>> $ cat /sys/kernel/debug/devfreq/devfreq_summary
>> dev name dev parent dev governor cur_freq min_freq max_freq
>> ------------------------------ ---------- ---------- --------------- ------------ ------------ ------------
>> 10c20000.memory-controller devfreq0 userspace 165000000 165000000 825000000
>> soc:bus_wcore devfreq1 simple_ondemand 400000000 84000000 400000000
>> soc:bus_noc devfreq2 devfreq1 passive 100000000 67000000 100000000
>> soc:bus_fsys_apb devfreq3 devfreq1 passive 200000000 100000000 200000000
>> soc:bus_fsys devfreq4 devfreq1 passive 200000000 100000000 200000000
>> soc:bus_fsys2 devfreq5 devfreq1 passive 150000000 75000000 150000000
>> soc:bus_mfc devfreq6 devfreq1 passive 333000000 96000000 333000000
>> soc:bus_gen devfreq7 devfreq1 passive 267000000 89000000 267000000
>> soc:bus_peri devfreq8 devfreq1 passive 67000000 67000000 67000000
>> soc:bus_g2d devfreq9 devfreq1 passive 333000000 84000000 333000000
>> soc:bus_g2d_acp devfreq10 devfreq1 passive 267000000 67000000 267000000
>> soc:bus_jpeg devfreq11 devfreq1 passive 300000000 75000000 300000000
>> soc:bus_jpeg_apb devfreq12 devfreq1 passive 167000000 84000000 167000000
>> soc:bus_disp1_fimd devfreq13 devfreq1 passive 200000000 120000000 200000000
>> soc:bus_disp1 devfreq14 devfreq1 passive 300000000 120000000 300000000
>> soc:bus_gscl_scaler devfreq15 devfreq1 passive 300000000 150000000 300000000
>> soc:bus_mscl devfreq16 devfreq1 passive 400000000 84000000 400000000
>>
>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>> drivers/devfreq/devfreq.c | 65 +++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 65 insertions(+)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index acd21345a070..d7177cc0a914 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -10,6 +10,7 @@
>> #include <linux/kernel.h>
>> #include <linux/kmod.h>
>> #include <linux/sched.h>
>> +#include <linux/debugfs.h>
>> #include <linux/errno.h>
>> #include <linux/err.h>
>> #include <linux/init.h>
>> @@ -33,6 +34,7 @@
>> #define HZ_PER_KHZ 1000
>>
>> static struct class *devfreq_class;
>> +static struct dentry *devfreq_debugfs;
>>
>> /*
>> * devfreq core provides delayed work based load monitoring helper
>> @@ -1670,6 +1672,62 @@ static struct attribute *devfreq_attrs[] = {
>> };
>> ATTRIBUTE_GROUPS(devfreq);
>>
>> +static int devfreq_summary_show(struct seq_file *s, void *data)
>> +{
>> + struct devfreq *devfreq;
>> + struct devfreq *parent_devfreq;
>> + unsigned long cur_freq, min_freq, max_freq;
>> +
>> + seq_printf(s, "%-30s %-10s %-10s %-15s %-12s %-12s %-12s\n",
>> + "dev name",
>> + "dev",
>> + "parent dev",
>> + "governor",
>> + "cur_freq",
>> + "min_freq",
>> + "max_freq");
>> + seq_printf(s, "%-30s %-10s %-10s %-15s %-12s %-12s %-12s\n",
>> + "------------------------------",
>> + "----------",
>> + "----------",
>> + "---------------",
>> + "------------",
>> + "------------",
>> + "------------");
>> +
>> + mutex_lock(&devfreq_list_lock);
>> +
>
> The 0day team has been doing builds with Clang and it pointed out that
> when CONFIG_DEVFREQ_GOV_PASSIVE is unset, parent_devfreq is always
> uninitialized. The else branch should probably be eliminated, moving the
> parent_devfreq NULL initialization above the if preprocessor directive.
>
> The full report is below.

Thanks for the report. I'll fix it as following:

struct devfreq *parent_devfreq = NULL;

>
>> + list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
>> +#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
>> + if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
>> + DEVFREQ_NAME_LEN)) {
>> + struct devfreq_passive_data *data = devfreq->data;
>> + parent_devfreq = data->parent;
>> + } else {
>> + parent_devfreq = NULL;
>> + }
>> +#endif
>> + mutex_lock(&devfreq->lock);
>> + cur_freq = devfreq->previous_freq,
>> + get_freq_range(devfreq, &min_freq, &max_freq);
>> + mutex_unlock(&devfreq->lock);
>> +
>> + seq_printf(s, "%-30s %-10s %-10s %-15s %-12ld %-12ld %-12ld\n",
>> + dev_name(devfreq->dev.parent),
>> + dev_name(&devfreq->dev),
>> + parent_devfreq ? dev_name(&parent_devfreq->dev) : "",
>> + devfreq->governor_name,
>> + cur_freq,
>> + min_freq,
>> + max_freq);
>> + }
>> +
>> + mutex_unlock(&devfreq_list_lock);
>> +
>> + return 0;
>> +}
>> +DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
>> +
>> static int __init devfreq_init(void)
>> {
>> devfreq_class = class_create(THIS_MODULE, "devfreq");
>> @@ -1686,6 +1744,13 @@ static int __init devfreq_init(void)
>> }
>> devfreq_class->dev_groups = devfreq_groups;
>>
>> + devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
>> + if (PTR_ERR(devfreq_debugfs) != -ENODEV && IS_ERR(devfreq_debugfs))
>> + pr_warn("%s: couldn't create debugfs dir\n", __FILE__);
>> +
>> + debugfs_create_file("devfreq_summary", 0444, devfreq_debugfs, NULL,
>> + &devfreq_summary_fops);
>> +
>> return 0;
>> }
>> subsys_initcall(devfreq_init);
>> --
>> 2.17.1
>>
>
> Cheers,
> Nathan
>
> On Thu, Dec 26, 2019 at 11:47:26PM +0800, kbuild test robot wrote:
>> CC: kbuild-all@lists.01.org
>> In-Reply-To: <20191226060749.13881-1-cw00.choi@samsung.com>
>> References: <20191226060749.13881-1-cw00.choi@samsung.com>
>> TO: Chanwoo Choi <cw00.choi@samsung.com>
>>
>> Hi Chanwoo,
>>
>> I love your patch! Perhaps something to improve:
>>
>> [auto build test WARNING on linux/master]
>> [also build test WARNING on linus/master v5.5-rc3 next-20191220]
>> [if your patch is applied to the wrong git tree, please drop us a note to help
>> improve the system. BTW, we also suggest to use '--base' option to specify the
>> base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
>>
>> url: https://protect2.fireeye.com/url?k=aa57311e-f7cb307e-aa56ba51-0cc47a31307c-5e67a2de952cf65a&u=https://github.com/0day-ci/linux/commits/Chanwoo-Choi/PM-devfreq-Add-debugfs-support-with-devfreq_summary-file/20191226-140227
>> base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 1522d9da40bdfe502c91163e6d769332897201fa
>> config: arm64-defconfig (attached as .config)
>> compiler: clang version 10.0.0 (git://gitmirror/llvm_project c5b4a2386b51a18daad7e42040c685c2e9708c47)
>> reproduce:
>> wget https://protect2.fireeye.com/url?k=e9857e19-b4197f79-e984f556-0cc47a31307c-e0c94321f498a093&u=https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>> chmod +x ~/bin/make.cross
>> # save the attached .config to linux build tree
>> make.cross ARCH=arm64
>>
>> If you fix the issue, kindly add following tag
>> Reported-by: kbuild test robot <lkp@intel.com>
>>
>> All warnings (new ones prefixed by >>):
>>
>>>> drivers/devfreq/devfreq.c:1653:4: warning: variable 'parent_devfreq' is uninitialized when used here [-Wuninitialized]
>> parent_devfreq ? dev_name(&parent_devfreq->dev) : "",
>> ^~~~~~~~~~~~~~
>> drivers/devfreq/devfreq.c:1613:32: note: initialize the variable 'parent_devfreq' to silence this warning
>> struct devfreq *parent_devfreq;
>> ^
>> = NULL
>> 1 warning generated.
>>
>> vim +/parent_devfreq +1653 drivers/devfreq/devfreq.c
>>
>> 1609
>> 1610 static int devfreq_summary_show(struct seq_file *s, void *data)
>> 1611 {
>> 1612 struct devfreq *devfreq;
>> 1613 struct devfreq *parent_devfreq;
>> 1614 unsigned long cur_freq, min_freq, max_freq;
>> 1615
>> 1616 seq_printf(s, "%-30s %-10s %-10s %-15s %-12s %-12s %-12s\n",
>> 1617 "dev name",
>> 1618 "dev",
>> 1619 "parent dev",
>> 1620 "governor",
>> 1621 "cur_freq",
>> 1622 "min_freq",
>> 1623 "max_freq");
>> 1624 seq_printf(s, "%-30s %-10s %-10s %-15s %-12s %-12s %-12s\n",
>> 1625 "------------------------------",
>> 1626 "----------",
>> 1627 "----------",
>> 1628 "---------------",
>> 1629 "------------",
>> 1630 "------------",
>> 1631 "------------");
>> 1632
>> 1633 mutex_lock(&devfreq_list_lock);
>> 1634
>> 1635 list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
>> 1636 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
>> 1637 if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
>> 1638 DEVFREQ_NAME_LEN)) {
>> 1639 struct devfreq_passive_data *data = devfreq->data;
>> 1640 parent_devfreq = data->parent;
>> 1641 } else {
>> 1642 parent_devfreq = NULL;
>> 1643 }
>> 1644 #endif
>> 1645 mutex_lock(&devfreq->lock);
>> 1646 cur_freq = devfreq->previous_freq,
>> 1647 get_freq_range(devfreq, &min_freq, &max_freq);
>> 1648 mutex_unlock(&devfreq->lock);
>> 1649
>> 1650 seq_printf(s, "%-30s %-10s %-10s %-15s %-12ld %-12ld %-12ld\n",
>> 1651 dev_name(devfreq->dev.parent),
>> 1652 dev_name(&devfreq->dev),
>>> 1653 parent_devfreq ? dev_name(&parent_devfreq->dev) : "",
>> 1654 devfreq->governor_name,
>> 1655 cur_freq,
>> 1656 min_freq,
>> 1657 max_freq);
>> 1658 }
>> 1659
>> 1660 mutex_unlock(&devfreq_list_lock);
>> 1661
>> 1662 return 0;
>> 1663 }
>> 1664 DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
>> 1665
>>
>> ---
>> 0-DAY kernel test infrastructure Open Source Technology Center
>> https://protect2.fireeye.com/url?k=f6f1d925-ab6dd845-f6f0526a-0cc47a31307c-7e8a6c295935ff12&u=https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation
>>
>
>


--
Best Regards,
Chanwoo Choi
Samsung Electronics

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