On Fri, Jul 08, 2022 at 11:41:38AM +0200, Johannes Zink wrote:
> This stores the probe deferral reason in the device structure.
> If a probe is permanently deferred, the last reason is displayed.
>
> Example output on a permanently deferred probe:
> ERROR: imx-pgc-domain0: probe permanently deferred (Failed to get domain's regulator)
>
> Other dev_err_probe outputs are displayed as before.
>
> Signed-off-by: Johannes Zink <j.zink@xxxxxxxxxxxxxx>
> ---
Applied, thanks
Sascha
> v1 -> v2:
> - improved commit message
> - improved function prototypes
> - improved debug output, device name is displayed once only per
> message
> - reverted removal of MSG_DEBUG output on deferred probe
> - replaced kfree by free
> - removed unnecessary null checks before free
> - fixed several typos
> - fixed compiler warnings
> - fixed coding style issues
> v2 -> v3:
> - dropped const from dev_err_probe
> - use xasprintf instead of basprintf: guarantee memory allocation
> - prevent newline within message on permanent deferral
> - removed unnecessary helper functions
> - fixed remaining typos and whitespace changes
> - improved comments
> - reverted removal of kernel doc comment
> - added example in commit message
> ---
> drivers/base/driver.c | 44 +++++++++++++++++++++++++++++++++++-------
> include/driver.h | 5 +++++
> include/linux/printk.h | 6 +++---
> 3 files changed, 45 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index 303ca061c..4898e0114 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -283,6 +283,7 @@ void free_device_res(struct device_d *dev)
> dev->name = NULL;
> free(dev->unique_name);
> dev->unique_name = NULL;
> + free(dev->deferred_probe_reason);
> }
> EXPORT_SYMBOL(free_device_res);
>
> @@ -333,9 +334,13 @@ static int device_probe_deferred(void)
> }
> } while (success);
>
> - list_for_each_entry(dev, &deferred, active)
> - dev_err(dev, "probe permanently deferred\n");
> -
> + list_for_each_entry(dev, &deferred, active) {
> + if (dev->deferred_probe_reason)
> + dev_err(dev, "probe permanently deferred (%s)\n",
> + dev->deferred_probe_reason);
> + else
> + dev_err(dev, "probe permanently deferred\n");
> + }
> return 0;
> }
> late_initcall(device_probe_deferred);
> @@ -573,6 +578,24 @@ const void *device_get_match_data(struct device_d *dev)
> return NULL;
> }
>
> +static void device_set_deferred_probe_reason(struct device_d *dev, const struct va_format *vaf)
> +{
> + char *reason;
> + char *last_char;
> +
> + free(dev->deferred_probe_reason);
> +
> + reason = xasprintf("%pV", vaf);
> +
> + /* drop newline char at end of reason string */
> + last_char = reason + strlen(reason) - 1;
> +
> + if (*last_char == '\n')
> + *last_char = '\0';
> +
> + dev->deferred_probe_reason = reason;
> +}
> +
> /**
> * dev_err_probe - probe error check and log helper
> * @loglevel: log level configured in source file
> @@ -584,8 +607,12 @@ const void *device_get_match_data(struct device_d *dev)
> * This helper implements common pattern present in probe functions for error
> * checking: print debug or error message depending if the error value is
> * -EPROBE_DEFER and propagate error upwards.
> - * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
> - * checked later by reading devices_deferred debugfs attribute.
> + *
> + * In case of -EPROBE_DEFER it sets the device's deferred_probe_reason attribute,
> + * but does not report an error. The error is recorded and displayed later, if
> + * (and only if) the probe is permanently deferred. For all other error codes,
> + * it just outputs the error along with the formatted message.
> + *
> * It replaces code sequence::
> *
> * if (err != -EPROBE_DEFER)
> @@ -601,8 +628,8 @@ const void *device_get_match_data(struct device_d *dev)
> * Returns @err.
> *
> */
> -int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...);
> -int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...)
> +int dev_err_probe(struct device_d *dev, int err, const char *fmt, ...);
> +int dev_err_probe(struct device_d *dev, int err, const char *fmt, ...)
> {
> struct va_format vaf;
> va_list args;
> @@ -611,6 +638,9 @@ int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...)
> vaf.fmt = fmt;
> vaf.va = &args;
>
> + if (err == -EPROBE_DEFER)
> + device_set_deferred_probe_reason(dev, &vaf);
> +
> dev_printf(err == -EPROBE_DEFER ? MSG_DEBUG : MSG_ERR,
> dev, "error %pe: %pV", ERR_PTR(err), &vaf);
>
> diff --git a/include/driver.h b/include/driver.h
> index b35b5f397..a89ce7af9 100644
> --- a/include/driver.h
> +++ b/include/driver.h
> @@ -88,6 +88,11 @@ struct device_d {
> * when the driver should actually detect client devices
> */
> int (*detect) (struct device_d *);
> +
> + /*
> + * if a driver probe is deferred, this stores the last error
> + */
> + char *deferred_probe_reason;
> };
>
> /** @brief Describes a driver present in the system */
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index 39523b057..e21e859bf 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -76,12 +76,12 @@ static inline int pr_print(int level, const char *format, ...)
> __dev_printf(8, (dev) , format , ## arg)
>
> #if LOGLEVEL >= MSG_ERR
> -int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...)
> +int dev_err_probe(struct device_d *dev, int err, const char *fmt, ...)
> __attribute__ ((format(__printf__, 3, 4)));
> #elif !defined(dev_err_probe)
> -static int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...)
> +static int dev_err_probe(struct device_d *dev, int err, const char *fmt, ...)
> __attribute__ ((format(__printf__, 3, 4)));
> -static inline int dev_err_probe(const struct device_d *dev, int err, const char *fmt, ...)
> +static inline int dev_err_probe(struct device_d *dev, int err, const char *fmt, ...)
> {
> return err;
> }
> --
> 2.30.2
>
>
>
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