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>
---
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
