| 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: <20ebd8e0-f74c-335c-4af8-35c3dc81902f@gmail.com>
Date: Tue, 14 Jan 2020 04:45:39 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Chanwoo Choi <cw00.choi@...sung.com>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: leonard.crestez@....com, lukasz.luba@....com, a.swigon@...sung.com,
m.szyprowski@...sung.com, enric.balletbo@...labora.com,
hl@...k-chips.com, bjorn.andersson@...aro.org,
jcrouse@...eaurora.org, chanwoo@...nel.org,
myungjoo.ham@...sung.com, kyungmin.park@...sung.com
Subject: Re: [PATCH v3] PM / devfreq: Add debugfs support with devfreq_summary
file
14.01.2020 04:45, Chanwoo Choi пишет:
> 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
>
> [Detailed description of each field of 'devfreq_summary' debugfs file]
> - dev_name : Device name of h/w.
> - dev : Device name made by devfreq core.
> - parent_dev : If devfreq device uses the passive governor,
> show parent devfreq device name. Otherwise, show 'null'.
> - governor : Devfreq governor.
> - polling_ms : If devfreq device uses the simple_ondemand governor,
> polling_ms is necessary for the period. (unit: millisecond)
> - cur_freq_Hz : Current Frequency (unit: Hz)
> - old_freq_Hz : Frequency before changing. (unit: Hz)
> - new_freq_Hz : Frequency after changed. (unit: Hz)
>
> [For example on Exynos5422-based Odroid-XU3 board]
> $ cat /sys/kernel/debug/devfreq/devfreq_summary
> dev_name dev parent_dev governor polling_ms cur_freq_Hz min_freq_Hz max_freq_Hz
> ------------------------------ ---------- ---------- --------------- ---------- ------------ ------------ ------------
> 10c20000.memory-controller devfreq0 null simple_ondemand 0 165000000 165000000 825000000
> soc:bus_wcore devfreq1 null simple_ondemand 50 532000000 88700000 532000000
> soc:bus_noc devfreq2 devfreq1 passive 0 111000000 66600000 111000000
> soc:bus_fsys_apb devfreq3 devfreq1 passive 0 222000000 111000000 222000000
> soc:bus_fsys devfreq4 devfreq1 passive 0 200000000 75000000 200000000
> soc:bus_fsys2 devfreq5 devfreq1 passive 0 200000000 75000000 200000000
> soc:bus_mfc devfreq6 devfreq1 passive 0 333000000 83250000 333000000
> soc:bus_gen devfreq7 devfreq1 passive 0 266000000 88700000 266000000
> soc:bus_peri devfreq8 devfreq1 passive 0 66600000 66600000 66600000
> soc:bus_g2d devfreq9 devfreq1 passive 0 333000000 83250000 333000000
> soc:bus_g2d_acp devfreq10 devfreq1 passive 0 266000000 66500000 266000000
> soc:bus_jpeg devfreq11 devfreq1 passive 0 300000000 75000000 300000000
> soc:bus_jpeg_apb devfreq12 devfreq1 passive 0 166500000 83250000 166500000
> soc:bus_disp1_fimd devfreq13 devfreq1 passive 0 200000000 120000000 200000000
> soc:bus_disp1 devfreq14 devfreq1 passive 0 300000000 120000000 300000000
> soc:bus_gscl_scaler devfreq15 devfreq1 passive 0 300000000 150000000 300000000
> soc:bus_mscl devfreq16 devfreq1 passive 0 666000000 84000000 666000000
>
> [lkp: Reported the build error]
> Reported-by: kbuild test robot <lkp@...el.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> ---
> Changes from v2:
> - Show 'null' at 'parent_dev' field when governor of devfreq device
> is not passive
> Changes from v1:
> - Drop the patch about 'devfreq_transitions' debugfs file
> - Modify from 'hz' to 'Hz'
> - Edit the indentation of 'devfreq_summary' when show summary
> - Exchange sequence between PTR_ERR and IS_ERR when debugfs_create_dir
>
> drivers/devfreq/devfreq.c | 84 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 84 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 89260b17598f..c5ef2d194b1b 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
> @@ -1643,6 +1645,79 @@ static struct attribute *devfreq_attrs[] = {
> };
> ATTRIBUTE_GROUPS(devfreq);
>
> +/**
> + * devfreq_summary_show() - Show the summary of the devfreq devices
> + * @s: seq_file instance to show the summary of devfreq devices
> + * @data: not used
> + *
> + * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
> + * It helps that user can know the detailed information of the devfreq devices.
> + *
> + * Return 0 always because it shows the information without any data change.
> + */
> +static int devfreq_summary_show(struct seq_file *s, void *data)
> +{
> + struct devfreq *devfreq;
> + struct devfreq *p_devfreq = NULL;
> + unsigned long cur_freq, min_freq, max_freq;
> + unsigned int polling_ms;
> +
> + seq_printf(s, "%-30s %-10s %-10s %-15s %10s %12s %12s %12s\n",
> + "dev_name",
> + "dev",
> + "parent_dev",
> + "governor",
> + "polling_ms",
> + "cur_freq_Hz",
> + "min_freq_Hz",
> + "max_freq_Hz");
> + seq_printf(s, "%30s %10s %10s %15s %10s %12s %12s %12s\n",
> + "------------------------------",
> + "----------",
> + "----------",
> + "---------------",
> + "----------",
> + "------------",
> + "------------",
> + "------------");
> +
> + mutex_lock(&devfreq_list_lock);
> +
> + list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
> + if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
> + DEVFREQ_NAME_LEN)) {
> + struct devfreq_passive_data *data = devfreq->data;
> +
> + if (data)
> + p_devfreq = data->parent;
> + } else {
> + p_devfreq = NULL;
> + }
> +
> + mutex_lock(&devfreq->lock);
> + cur_freq = devfreq->previous_freq,
> + get_freq_range(devfreq, &min_freq, &max_freq);
> + polling_ms = devfreq->profile->polling_ms,
> + mutex_unlock(&devfreq->lock);
> +
> + seq_printf(s,
> + "%-30s %-10s %-10s %-15s %10d %12ld %12ld %12ld\n",
> + dev_name(devfreq->dev.parent),
> + dev_name(&devfreq->dev),
> + p_devfreq ? dev_name(&p_devfreq->dev) : "null",
> + devfreq->governor_name,
> + polling_ms,
> + 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");
> @@ -1659,6 +1734,15 @@ static int __init devfreq_init(void)
> }
> devfreq_class->dev_groups = devfreq_groups;
>
> + devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
> + if (IS_ERR(devfreq_debugfs) && PTR_ERR(devfreq_debugfs) != -ENODEV) {
> + pr_warn("%s: couldn't create debugfs dir\n", __FILE__);
If you'll take a look at [1], you may notice that it could fail only in
a single place in the code and in that case the error message is already
printed.
[1] https://elixir.bootlin.com/linux/v5.5-rc6/source/fs/debugfs/inode.c#L543
> + } else {
> + debugfs_create_file("devfreq_summary", 0444,
> + devfreq_debugfs, NULL,
> + &devfreq_summary_fops);
If you'll you'll take a look at [2], you may notice notice that it
checks whether devfreq_debugfs IS_ERR [3] and then bails out.
[2] https://elixir.bootlin.com/linux/v5.5-rc6/source/fs/debugfs/inode.c#L432
[3] https://elixir.bootlin.com/linux/v5.5-rc6/source/fs/debugfs/inode.c#L316
Thus you could simply remove the above error handling, making code to
look cleaner.
Powered by blists - more mailing lists