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Subject[PATCH v7 1/4] driver core: add device probe log helper
Date
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>
---
drivers/base/core.c | 42 ++++++++++++++++++++++++++++++++++++++++++
include/linux/device.h | 3 +++
2 files changed, 45 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 67d39a90b45c..3a827c82933f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3953,6 +3953,48 @@ 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 15460a5ac024..6b2272ae9af8 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -964,6 +964,9 @@ 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))
--
2.17.1
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