driver core: add device probe log helper

During probe every time driver gets resource it should usually check for
error printk some message if it is not -EPROBE_DEFER and return the error.
This pattern is simple but requires adding few lines after any resource
acquisition code, as a result it is often omitted or implemented only
partially.
dev_err_probe helps to replace such code sequences with simple call,
so code:
	if (err != -EPROBE_DEFER)
		dev_err(dev, ...);
	return err;
becomes:
	return dev_err_probe(dev, err, ...);

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200713144324.23654-2-a.hajda@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4d05868d9356b95e6d77f72a556a8ecd722112c6..1606488ed741993b62d2ec8596a9af85c549cadb 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -4203,6 +4203,48 @@ define_dev_printk_level(_dev_info, KERN_INFO);
 
 #endif
 
+/**
+ * dev_err_probe - probe error check and log helper
+ * @dev: the pointer to the struct device
+ * @err: error value to test
+ * @fmt: printf-style format string
+ * @...: arguments as specified in the format string
+ *
+ * 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.
+ * It replaces code sequence:
+ *     if (err != -EPROBE_DEFER)
+ *             dev_err(dev, ...);
+ *     else
+ *             dev_dbg(dev, ...);
+ *     return err;
+ * with
+ *     return dev_err_probe(dev, err, ...);
+ *
+ * Returns @err.
+ *
+ */
+int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
+{
+       struct va_format vaf;
+       va_list args;
+
+       va_start(args, fmt);
+       vaf.fmt = fmt;
+       vaf.va = &args;
+
+       if (err != -EPROBE_DEFER)
+               dev_err(dev, "error %d: %pV", err, &vaf);
+       else
+               dev_dbg(dev, "error %d: %pV", err, &vaf);
+
+       va_end(args);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(dev_err_probe);
+
 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
 {
        return fwnode && !IS_ERR(fwnode->secondary);

diff --git a/include/linux/device.h b/include/linux/device.h
index a120657d75878e9aa27488721f5c8d6833a607aa..065c24008f8b27577e834ff7ee4056f682978fc5 100644 (file)
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -962,6 +962,9 @@ void device_link_remove(void *consumer, struct device *supplier);
 void device_links_supplier_sync_state_pause(void);
 void device_links_supplier_sync_state_resume(void);
 
+extern __printf(3, 4)
+int dev_err_probe(const struct device *dev, int err, const char *fmt, ...);
+
 /* Create alias, so I can be autoloaded. */
 #define MODULE_ALIAS_CHARDEV(major,minor) \
        MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))