- Add it under 'Core API' because I think that's where it lives.
- Promote the header to a more prominent header type, otherwise we get three
entries in the table of contents.
- Reformat the table to look nicer and be a little more proportional in
terms of horizontal width per bit (the SF bit is still disproportionately
large, but there's no way to fix that).
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
index eb16ba30aeb6..b8ec120c24f9 100644
--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -22,6 +22,7 @@ Core utilities
flexible-arrays
librs
genalloc
+ ../errseq
Interfaces for kernel debugging
===============================
diff --git a/Documentation/errseq.rst b/Documentation/errseq.rst
index 4c29bd5afbc5..7c3ac9639ebf 100644
--- a/Documentation/errseq.rst
+++ b/Documentation/errseq.rst
@@ -1,5 +1,7 @@
+=====================
The errseq_t datatype
=====================
+
An errseq_t is a way of recording errors in one place, and allowing any
number of "subscribers" to tell whether it has changed since a previous
point where it was sampled.
@@ -21,12 +23,13 @@ a flag to tell whether the value has been sampled since a new value was
recorded. That allows us to avoid bumping the counter if no one has
sampled it since the last time an error was recorded.
-Thus we end up with a value that looks something like this::
+Thus we end up with a value that looks something like this:
- bit: 31..13 12 11..0
- +-----------------+----+----------------+
- | counter | SF | errno |
- +-----------------+----+----------------+
++--------------------------------------+----+------------------------+
+| 31..13 | 12 | 11..0 |
++--------------------------------------+----+------------------------+
+| counter | SF | errno |
++--------------------------------------+----+------------------------+
The general idea is for "watchers" to sample an errseq_t value and keep
it as a running cursor. That value can later be used to tell whether
@@ -42,6 +45,7 @@ has ever been an error set since it was first initialized.
API usage
=========
+
Let me tell you a story about a worker drone. Now, he's a good worker
overall, but the company is a little...management heavy. He has to
report to 77 supervisors today, and tomorrow the "big boss" is coming in
@@ -125,6 +129,7 @@ not usable by anyone else.
Serializing errseq_t cursor updates
===================================
+
Note that the errseq_t API does not protect the errseq_t cursor during a
check_and_advance_operation. Only the canonical error code is handled
atomically. In a situation where more than one task might be using the
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