The pr_<foo> convenience macros

The convenience pr_<foo>() macros given here ease coding pain. The clunky 
 printk(KERN_FOO "<format-str>"); is replaced with the elegant
pr_foo("<format-str>");, where <foo> is the log level; their use is encouraged:

// include/linux/printk.h:
[...]
/*
 * These can be used to print at the various log levels.
 * All of these will print unconditionally, although note that pr_debug()
 * and other debug macros are compiled out unless either DEBUG is defined
 * or CONFIG_DYNAMIC_DEBUG is set.
 */
#define pr_emerg(fmt, ...) \
        printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
#define pr_alert(fmt, ...) \
        printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_crit(fmt, ...) \
        printk(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_err(fmt, ...) \
        printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
#define pr_warning(fmt, ...) \
        printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
#define...