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Message-ID: <58932d61-0aab-7738-97a1-2eda3bcda0ec@quicinc.com>
Date: Wed, 30 Oct 2024 18:20:43 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
CC: <sudeep.holla@....com>, <cristian.marussi@....com>,
<jassisinghbrar@...il.com>, <dmitry.baryshkov@...aro.org>,
<linux-kernel@...r.kernel.org>, <arm-scmi@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-arm-msm@...r.kernel.org>, <johan@...nel.org>,
<konradybcio@...nel.org>, <linux-pm@...r.kernel.org>,
<tstrudel@...gle.com>, <rafael@...nel.org>,
Johan Hovold
<johan+linaro@...nel.org>
Subject: Re: [PATCH V4 3/4] pmdomain: core: Fix debugfs node creation failure
On 10/28/24 18:58, Ulf Hansson wrote:
> On Wed, 23 Oct 2024 at 12:22, Sibi Sankar <quic_sibis@...cinc.com> wrote:
>>
>> The domain attributes returned by the perf protocol can end up
>> reporting identical names across domains, resulting in debugfs
>> node creation failure. Fix this failure by ensuring that pm domains
>> get a unique name using ida in pm_genpd_init.
>>
>> Logs: [X1E reports 'NCC' for all its scmi perf domains]
>> debugfs: Directory 'NCC' with parent 'pm_genpd' already present!
>> debugfs: Directory 'NCC' with parent 'pm_genpd' already present!
>>
>> Reported-by: Johan Hovold <johan+linaro@...nel.org>
>> Closes: https://lore.kernel.org/lkml/ZoQjAWse2YxwyRJv@hovoldconsulting.com/
>> Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains")
>> Suggested-by: Ulf Hansson <ulf.hansson@...aro.org>
>> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
>> ---
>>
>> v3:
>> * Update device names only when a name collision occurs [Dmitry/Ulf]
>> * Drop Johan's T-b from "fix debugfs node creation failure"
>>
>> drivers/pmdomain/core.c | 65 ++++++++++++++++++++++++++++++---------
>> include/linux/pm_domain.h | 1 +
>> 2 files changed, 51 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
>> index 76490f0bf1e2..756ed0975788 100644
>> --- a/drivers/pmdomain/core.c
>> +++ b/drivers/pmdomain/core.c
>> @@ -7,6 +7,7 @@
>> #define pr_fmt(fmt) "PM: " fmt
>>
>> #include <linux/delay.h>
>> +#include <linux/idr.h>
>> #include <linux/kernel.h>
>> #include <linux/io.h>
>> #include <linux/platform_device.h>
>> @@ -23,6 +24,9 @@
>> #include <linux/cpu.h>
>> #include <linux/debugfs.h>
>>
>> +/* Provides a unique ID for each genpd device */
>> +static DEFINE_IDA(genpd_ida);
>> +
>> #define GENPD_RETRY_MAX_MS 250 /* Approximate */
>>
>> #define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \
>> @@ -189,7 +193,7 @@ static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
>>
>> if (ret)
>> dev_warn_once(dev, "PM domain %s will not be powered off\n",
>> - genpd->name);
>> + dev_name(&genpd->dev));
>>
>> return ret;
>> }
>> @@ -274,7 +278,7 @@ static void genpd_debug_remove(struct generic_pm_domain *genpd)
>> if (!genpd_debugfs_dir)
>> return;
>>
>> - debugfs_lookup_and_remove(genpd->name, genpd_debugfs_dir);
>> + debugfs_lookup_and_remove(dev_name(&genpd->dev), genpd_debugfs_dir);
>> }
>>
>> static void genpd_update_accounting(struct generic_pm_domain *genpd)
>> @@ -731,7 +735,7 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>> genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
>> genpd->gd->max_off_time_changed = true;
>> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
>> - genpd->name, "on", elapsed_ns);
>> + dev_name(&genpd->dev), "on", elapsed_ns);
>>
>> out:
>> raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_ON, NULL);
>> @@ -782,7 +786,7 @@ static int _genpd_power_off(struct generic_pm_domain *genpd, bool timed)
>> genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
>> genpd->gd->max_off_time_changed = true;
>> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
>> - genpd->name, "off", elapsed_ns);
>> + dev_name(&genpd->dev), "off", elapsed_ns);
>>
>> out:
>> raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_OFF,
>> @@ -1941,7 +1945,7 @@ int dev_pm_genpd_add_notifier(struct device *dev, struct notifier_block *nb)
>>
>> if (ret) {
>> dev_warn(dev, "failed to add notifier for PM domain %s\n",
>> - genpd->name);
>> + dev_name(&genpd->dev));
>> return ret;
>> }
>>
>> @@ -1988,7 +1992,7 @@ int dev_pm_genpd_remove_notifier(struct device *dev)
>>
>> if (ret) {
>> dev_warn(dev, "failed to remove notifier for PM domain %s\n",
>> - genpd->name);
>> + dev_name(&genpd->dev));
>> return ret;
>> }
>>
>> @@ -2014,7 +2018,7 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,
>> */
>> if (!genpd_is_irq_safe(genpd) && genpd_is_irq_safe(subdomain)) {
>> WARN(1, "Parent %s of subdomain %s must be IRQ safe\n",
>> - genpd->name, subdomain->name);
>> + dev_name(&genpd->dev), subdomain->name);
>> return -EINVAL;
>> }
>>
>> @@ -2089,7 +2093,7 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
>>
>> if (!list_empty(&subdomain->parent_links) || subdomain->device_count) {
>> pr_warn("%s: unable to remove subdomain %s\n",
>> - genpd->name, subdomain->name);
>> + dev_name(&genpd->dev), subdomain->name);
>> ret = -EBUSY;
>> goto out;
>> }
>> @@ -2199,6 +2203,23 @@ static void genpd_lock_init(struct generic_pm_domain *genpd)
>> }
>> }
>>
>> +static bool genpd_name_present(const char *name)
>> +{
>> + bool ret = false;
>> + const struct generic_pm_domain *gpd;
>> +
>> + mutex_lock(&gpd_list_lock);
>> + list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
>> + if (!strcmp(dev_name(&gpd->dev), name)) {
>> + ret = true;
>> + break;
>> + }
>> + }
>> + mutex_unlock(&gpd_list_lock);
>> +
>> + return ret;
>> +}
>> +
>> /**
>> * pm_genpd_init - Initialize a generic I/O PM domain object.
>> * @genpd: PM domain object to initialize.
>> @@ -2226,6 +2247,7 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
>> genpd->status = is_off ? GENPD_STATE_OFF : GENPD_STATE_ON;
>> genpd->device_count = 0;
>> genpd->provider = NULL;
>> + genpd->device_id = -ENXIO;
>> genpd->has_provider = false;
>> genpd->accounting_time = ktime_get_mono_fast_ns();
>> genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
>> @@ -2266,7 +2288,18 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
>> return ret;
>>
>> device_initialize(&genpd->dev);
>> - dev_set_name(&genpd->dev, "%s", genpd->name);
>> +
>> + if (!genpd_name_present(genpd->name)) {
>> + dev_set_name(&genpd->dev, "%s", genpd->name);
>> + } else {
>> + ret = ida_alloc(&genpd_ida, GFP_KERNEL);
>> + if (ret < 0) {
>> + put_device(&genpd->dev);
>> + return ret;
>> + }
>> + genpd->device_id = ret;
>> + dev_set_name(&genpd->dev, "%s_%u", genpd->name, genpd->device_id);
>> + }
>
> If we can't assume that the genpd->name is unique, I think we need to
> hold the gpd_list_lock over this entire new section, until we have
> added the new genpd in the gpd_list. I am not sure we really want this
> as it could hurt (theoretically at least) boot/probing on systems
> where a lot of genpds are being used.
>
> That said, I would suggest we go for Dmitry's suggestion to make this
> genpd provider specific. Let's add a new genpd flag that genpd
> providers can set, if they need an ida to be tagged on to their
> device-name. Then we should set that flag for SCMI perf/power domains.
lol, will do ^^ in the next re-spin.
-Sibi
>
> [...]
>
> Kind regards
> Uffe
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