WSL2-Linux-Kernel/include
Chris Down ad7d61f159 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 <chris@chrisdown.name>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/959c7aed1017cb2c9de922e0a820d397e29c6a5a.1623775748.git.chris@chrisdown.name
2021-07-19 12:13:06 +02:00
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acpi IOMMU Updates for Linux v5.14 2021-07-02 13:22:47 -07:00
asm-generic printk: Userspace format indexing support 2021-07-19 11:57:48 +02:00
clocksource
crypto
drm
dt-bindings ARM: Drivers for 5.14 2021-07-10 09:46:20 -07:00
keys
kunit linux-kselftest-kunit-fixes-5.14-rc1 2021-07-02 12:58:26 -07:00
kvm
linux printk: index: Add indexing support to dev_printk 2021-07-19 12:13:06 +02:00
math-emu
media
memory
misc
net Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:30:04 -07:00
pcmcia
ras
rdma
scsi SCSI misc on 20210702 2021-07-02 15:14:36 -07:00
soc ARM: Drivers for 5.14 2021-07-10 09:46:20 -07:00
sound ASoC: Updates for v5.14 2021-07-01 08:36:12 +02:00
target
trace Merge branch 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu 2021-07-04 12:58:33 -07:00
uapi block-5.14-2021-07-08 2021-07-09 12:05:33 -07:00
vdso
video
xen xen: sync include/xen/interface/io/ring.h with Xen's newest version 2021-07-05 09:49:45 +02:00