printk: Move the printk() kerneldoc comment to its new home

[platform/kernel/linux-starfive.git] / include / linux / printk.h

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 2651b82..c1e1764 100644 (file)
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -431,6 +431,30 @@ struct pi_entry {
        })
 
 
+/**
+ * printk - print a kernel message
+ * @fmt: format string
+ *
+ * This is printk(). It can be called from any context. We want it to work.
+ *
+ * If printk indexing is enabled, _printk() is called from printk_index_wrap.
+ * Otherwise, printk is simply #defined to _printk.
+ *
+ * We try to grab the console_lock. If we succeed, it's easy - we log the
+ * output and call the console drivers.  If we fail to get the semaphore, we
+ * place the output into the log buffer and return. The current holder of
+ * the console_sem will notice the new output in console_unlock(); and will
+ * send it to the consoles before releasing the lock.
+ *
+ * One effect of this deferred printing is that code which calls printk() and
+ * then changes console_loglevel may break. This is because console_loglevel
+ * is inspected when the actual printing occurs.
+ *
+ * See also:
+ * printf(3)
+ *
+ * See the vsnprintf() documentation for format string extensions over C99.
+ */
 #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
 #define printk_deferred(fmt, ...)                                      \
        printk_index_wrap(_printk_deferred, fmt, ##__VA_ARGS__)