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 <[email protected]> --- 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
