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Message-ID: <94ed179a-bcc7-1e52-985f-57e9c124a5f0@samsung.com>
Date: Wed, 24 Jun 2020 15:26:15 +0200
From: Andrzej Hajda <a.hajda@...sung.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jernej Skrabec <jernej.skrabec@...l.net>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
linux-kernel@...r.kernel.org,
"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
Russell King - ARM Linux <linux@...linux.org.uk>,
Neil Armstrong <narmstrong@...libre.com>,
Jonas Karlman <jonas@...boo.se>, andy.shevchenko@...il.com,
Mark Brown <broonie@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
linux-arm-kernel@...ts.infradead.org,
Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [RESEND PATCH v5 2/5] driver core: add deferring probe reason
to devices_deferred property
On 24.06.2020 14:34, Greg Kroah-Hartman wrote:
> On Wed, Jun 24, 2020 at 01:41:24PM +0200, Andrzej Hajda wrote:
>> /sys/kernel/debug/devices_deferred property contains list of deferred devices.
>> This list does not contain reason why the driver deferred probe, the patch
>> improves it.
>> The natural place to set the reason is probe_err function introduced recently,
>> ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
>> will be attached to deferred device and printed when user read devices_deferred
>> property.
>>
>> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
>> Reviewed-by: Mark Brown <broonie@...nel.org>
>> Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> ---
>> drivers/base/base.h | 3 +++
>> drivers/base/core.c | 10 ++++++----
>> drivers/base/dd.c | 21 ++++++++++++++++++++-
>> 3 files changed, 29 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/base/base.h b/drivers/base/base.h
>> index 95c22c0f9036..93ef1c2f4c1f 100644
>> --- a/drivers/base/base.h
>> +++ b/drivers/base/base.h
>> @@ -93,6 +93,7 @@ struct device_private {
>> struct klist_node knode_class;
>> struct list_head deferred_probe;
>> struct device_driver *async_driver;
>> + char *deferred_probe_msg;
>> struct device *device;
>> u8 dead:1;
>> };
>> @@ -134,6 +135,8 @@ extern void device_release_driver_internal(struct device *dev,
>> extern void driver_detach(struct device_driver *drv);
>> extern int driver_probe_device(struct device_driver *drv, struct device *dev);
>> extern void driver_deferred_probe_del(struct device *dev);
>> +extern void __deferred_probe_set_msg(const struct device *dev,
>> + struct va_format *vaf);
>> static inline int driver_match_device(struct device_driver *drv,
>> struct device *dev)
>> {
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index ee9da66bff1b..2a96954d5460 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -3962,6 +3962,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>> *
>> * This helper implements common pattern present in probe functions for error
>> * checking: print message if the error is not -EPROBE_DEFER and propagate it.
>> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
>> + * later by reading devices_deferred debugfs attribute.
>> * It replaces code sequence:
>> * if (err != -EPROBE_DEFER)
>> * dev_err(dev, ...);
>> @@ -3977,14 +3979,14 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>> struct va_format vaf;
>> va_list args;
>>
>> - if (err == -EPROBE_DEFER)
>> - return err;
>> -
>> va_start(args, fmt);
>> vaf.fmt = fmt;
>> vaf.va = &args;
>>
>> - dev_err(dev, "error %d: %pV", err, &vaf);
>> + if (err == -EPROBE_DEFER)
>> + __deferred_probe_set_msg(dev, &vaf);
>> + else
>> + dev_err(dev, "error %d: %pV", err, &vaf);
>>
>> va_end(args);
>>
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index 9a1d940342ac..f44d26454b6a 100644
>> --- a/drivers/base/dd.c
>> +++ b/drivers/base/dd.c
>> @@ -27,6 +27,7 @@
>> #include <linux/async.h>
>> #include <linux/pm_runtime.h>
>> #include <linux/pinctrl/devinfo.h>
>> +#include <linux/slab.h>
>>
>> #include "base.h"
>> #include "power/power.h"
>> @@ -136,6 +137,8 @@ void driver_deferred_probe_del(struct device *dev)
>> if (!list_empty(&dev->p->deferred_probe)) {
>> dev_dbg(dev, "Removed from deferred list\n");
>> list_del_init(&dev->p->deferred_probe);
>> + kfree(dev->p->deferred_probe_msg);
>> + dev->p->deferred_probe_msg = NULL;
>> }
>> mutex_unlock(&deferred_probe_mutex);
>> }
>> @@ -211,6 +214,21 @@ void device_unblock_probing(void)
>> driver_deferred_probe_trigger();
>> }
>>
>> +/*
>> + * __deferred_probe_set_msg() - Set defer probe reason message for device
>> + */
>> +void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
>> +{
>> + const char *drv = dev_driver_string(dev);
>> +
>> + mutex_lock(&deferred_probe_mutex);
>> +
>> + kfree(dev->p->deferred_probe_msg);
>> + dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
> What about the device name? Don't you also want that?
deferred_devs_show prints it already, deferred_probe_msg is appended if
not null.
Regards
Andrzej
>
> You want the same format that __dev_printk() outputs, please use that
> to be consistant with all other messages that drivers are spitting out.
>
> thanks,
>
> greg k-h
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