[PATCHv8 13/13] init.h: add some more documentation to __ref* tags

From: Michal Nazarewicz
Date: Thu Aug 12 2010 - 11:43:28 EST


The __ref* tags may have been confusing for new kernel
developers (I was confused by them for sure) so adding a few
more sentences to comment to clear things up for people who
see those for the first time.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
Acked-by: Uwe Kleine-KÃnig <u.kleine-koenig@xxxxxxxxxxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
---
include/linux/init.h | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index de99430..577671c 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -46,16 +46,23 @@
#define __exitdata __section(.exit.data)
#define __exit_call __used __section(.exitcall.exit)

-/* modpost check for section mismatches during the kernel build.
+/*
+ * modpost check for section mismatches during the kernel build.
* A section mismatch happens when there are references from a
* code or data section to an init section (both code or data).
* The init sections are (for most archs) discarded by the kernel
* when early init has completed so all such references are potential bugs.
* For exit sections the same issue exists.
+ *
* The following markers are used for the cases where the reference to
* the *init / *exit section (code or data) is valid and will teach
- * modpost not to issue a warning.
- * The markers follow same syntax rules as __init / __initdata. */
+ * modpost not to issue a warning. Intended semantics is that a code or
+ * data tagged __ref* can reference code or data from init section without
+ * producing a warning (of course, no warning does not mean code is
+ * correct, so optimally document why the __ref is needed and why it's OK).
+ *
+ * The markers follow same syntax rules as __init / __initdata.
+ */
#define __ref __section(.ref.text) noinline
#define __refdata __section(.ref.data)
#define __refconst __section(.ref.rodata)
--
1.7.1

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