docs: fault-injection: add requirements of error injectable functions

Add a section about the requirements of the error injectable functions and
the type of errors.

Since this section must be read before using ALLOW_ERROR_INJECTION()
macro, that section is referred from the comment of the macro too.

Link: https://lkml.kernel.org/r/167081321427.387937.15475445689482551048.stgit@devnote3
Link: https://lore.kernel.org/all/[email protected]/T/#u
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Florent Revest <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/asm-generic/error-injection.h b/include/asm-generic/error-injection.h
index c0b9d3217ed9..b05253f68eaa 100644
--- a/include/asm-generic/error-injection.h
+++ b/include/asm-generic/error-injection.h
@@ -19,8 +19,10 @@ struct pt_regs;
 
 #ifdef CONFIG_FUNCTION_ERROR_INJECTION
 /*
- * Whitelist generating macro. Specify functions which can be
- * error-injectable using this macro.
+ * Whitelist generating macro. Specify functions which can be error-injectable
+ * using this macro. If you unsure what is required for the error-injectable
+ * functions, please read Documentation/fault-injection/fault-injection.rst
+ * 'Error Injectable Functions' section.
  */
 #define ALLOW_ERROR_INJECTION(fname, _etype)				\
 static struct error_injection_entry __used				\