From ad7d61f159db73974f1b0352f21afe04b0bbd920 Mon Sep 17 00:00:00 2001 From: Chris Down Date: Tue, 15 Jun 2021 17:52:56 +0100 Subject: printk: index: Add indexing support to dev_printk While for most kinds of issues we have counters, tracepoints, or metrics with a stable interface which can reliably be used to indicate issues, in order to react to production issues quickly we sometimes need to work with the interface which most kernel developers naturally use when developing: printk, and printk-esques like dev_printk. dev_printk is by far the most likely custom subsystem printk to benefit from the printk indexing infrastructure, since niche device issues brought about by production changes, firmware upgrades, and the like are one of the most common things that we need printk infrastructure's assistance to monitor. Often these errors were never expected to practically manifest in reality, and exhibit in code without extensive (or any) metrics present. As such, there are typically very few options for issue detection available to those with large fleets at the time the incident happens, and we thus benefit strongly from monitoring netconsole in these instances. As such, add the infrastructure for dev_printk to be indexed in the printk index. Even on a minimal kernel config, the coverage of the base kernel's printk index is significantly improved: Before: [root@ktst ~]# wc -l /sys/kernel/debug/printk/index/vmlinux 4497 /sys/kernel/debug/printk/index/vmlinux After: [root@ktst ~]# wc -l /sys/kernel/debug/printk/index/vmlinux 5573 /sys/kernel/debug/printk/index/vmlinux In terms of implementation, in order to trivially disambiguate them, dev_printk is now a macro which wraps _dev_printk. Signed-off-by: Chris Down Cc: Petr Mladek Cc: Greg Kroah-Hartman Cc: Rasmus Villemoes Reviewed-by: Petr Mladek Tested-by: Petr Mladek Acked-by: Andy Shevchenko Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/959c7aed1017cb2c9de922e0a820d397e29c6a5a.1623775748.git.chris@chrisdown.name --- drivers/base/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index cadcade65825..613497f45224 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -4579,8 +4579,8 @@ static void __dev_printk(const char *level, const struct device *dev, printk("%s(NULL device *): %pV", level, vaf); } -void dev_printk(const char *level, const struct device *dev, - const char *fmt, ...) +void _dev_printk(const char *level, const struct device *dev, + const char *fmt, ...) { struct va_format vaf; va_list args; @@ -4594,7 +4594,7 @@ void dev_printk(const char *level, const struct device *dev, va_end(args); } -EXPORT_SYMBOL(dev_printk); +EXPORT_SYMBOL(_dev_printk); #define define_dev_printk_level(func, kern_level) \ void func(const struct device *dev, const char *fmt, ...) \ -- cgit v1.2.3