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SubjectRe: [PATCH 2/3] driver core: add deferring probe reason to devices_deferred property
On Tue, Oct 16, 2018 at 10:22 AM Andrzej Hajda <a.hajda@samsung.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.


> - if (err != -EPROBE_DEFER) {
> - va_start(args, fmt);
> + va_start(args, fmt);
>
> - vaf.fmt = fmt;
> - vaf.va = &args;
> + vaf.fmt = fmt;
> + vaf.va = &args;
>
> + if (err != -EPROBE_DEFER)
> __dev_printk(KERN_ERR, dev, &vaf);
> - va_end(args);
> - }
> + else
> + __deferred_probe_set_msg(dev, fmt, args);
> +
> + va_end(args);

Yeah, ping-pong style of programming (one patch "amends" something
which had been introduced by another).
That's why better to follow my comment for the patch 1.

> +/*
> + * __deferred_probe_set_msg() - Set defer probe reason message for device
> + */
> +void __deferred_probe_set_msg(const struct device *dev, const char *fmt,
> + va_list args)
> +{
> + const int size = 128;
> + char **p;
> + int n;
> +
> + mutex_lock(&deferred_probe_mutex);
> +


> + p = &dev->p->deferred_probe_msg;
> + if (!*p) {
> + *p = kmalloc(size, GFP_KERNEL);
> + if (!*p)
> + goto end;
> + }
> + n = snprintf(*p, size, "%s %s: ", dev_driver_string(dev), dev_name(dev));
> + if (n < size)
> + vsnprintf(*p + n, size - n, fmt, args);

Perhaps kasprintf() instead of this huge plays around the size and allocation?

> list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
> - seq_printf(s, "%s\n", dev_name(curr->device));
> + if (curr->device->p->deferred_probe_msg)
> + seq_puts(s, curr->device->p->deferred_probe_msg);
> + else
> + seq_printf(s, "%s\n", dev_name(curr->device));

I wouldn't care (much) about debugfs, though better to keep some order
here, i.e. always print device name.

Something like

seq_printf(s, "%s\t%s\n", dev_name(), deferred_probe_msg ?: "");

and remove that part from above __deferred_probe_set_msg().

--
With Best Regards,
Andy Shevchenko

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