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Message-ID: <CAJZ5v0hv-jKSegVtNQ2uMde5A6hQ0_ksK0m1CBapqaXZWmV_zg@mail.gmail.com>
Date: Wed, 24 Jun 2020 14:11:28 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Andrzej Hajda <a.hajda@...sung.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Mark Brown <broonie@...nel.org>,
Russell King - ARM Linux <linux@...linux.org.uk>,
Neil Armstrong <narmstrong@...libre.com>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...l.net>,
Daniel Vetter <daniel@...ll.ch>,
"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>
Subject: Re: [RESEND PATCH v5 2/5] driver core: add deferring probe reason to
devices_deferred property
On Wed, Jun 24, 2020 at 1:41 PM Andrzej Hajda <a.hajda@...sung.com> 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;
What about calling this deferred_probe_reason?
> 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);
I'd call this device_set_deferred_probe_reson() to follow the naming
convention for the function names in this header file.
> 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
I'd change this into a full kerneldoc comment.
> + */
> +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);
> +
> + mutex_unlock(&deferred_probe_mutex);
> +}
> +
> /*
> * deferred_devs_show() - Show the devices in the deferred probe pending list.
> */
> @@ -221,7 +239,8 @@ static int deferred_devs_show(struct seq_file *s, void *data)
> mutex_lock(&deferred_probe_mutex);
>
> list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
> - seq_printf(s, "%s\n", dev_name(curr->device));
> + seq_printf(s, "%s\t%s", dev_name(curr->device),
> + curr->device->p->deferred_probe_msg ?: "\n");
>
> mutex_unlock(&deferred_probe_mutex);
>
> --
> 2.17.1
>
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