From 78f101a1b25848a364c632237ee6a7a6ec468235 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@alien8.de>
Date: Tue, 22 Dec 2020 14:05:55 +0100
Subject: [PATCH] Documentation/submitting-patches: Add blurb about backtraces
 in commit messages

Document that backtraces in commit messages should be trimmed down to
the useful information only.

This has been carved out from a tip subsystem handbook patchset by
Thomas Gleixner:

  https://lkml.kernel.org/r/20181107171010.421878737@linutronix.de

and incorporates follow-on comments.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
---
 Documentation/process/submitting-patches.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/process/submitting-patches.rst b/Documentation/process/submitting-patches.rst
index 7f48cccc75cdf..8c991c8636280 100644
--- a/Documentation/process/submitting-patches.rst
+++ b/Documentation/process/submitting-patches.rst
@@ -684,6 +684,26 @@ generates appropriate diffstats by default.)
 See more details on the proper patch format in the following
 references.
 
+Backtraces in commit mesages
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Backtraces help document the call chain leading to a problem. However,
+not all backtraces are helpful. For example, early boot call chains are
+unique and obvious. Copying the full dmesg output verbatim, however,
+adds distracting information like timestamps, module lists, register and
+stack dumps.
+
+Therefore, the most useful backtraces should distill the relevant
+information from the dump, which makes it easier to focus on the real
+issue. Here is an example of a well-trimmed backtrace::
+
+  unchecked MSR access error: WRMSR to 0xd51 (tried to write 0x0000000000000064)
+  at rIP: 0xffffffffae059994 (native_write_msr+0x4/0x20)
+  Call Trace:
+  mba_wrmsr
+  update_domains
+  rdtgroup_mkdir
+
 .. _explicit_in_reply_to:
 
 Explicit In-Reply-To headers
-- 
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