Subject: + documentation-expand-clarify-debug-documentation.patch added to -mm tree
To: ddstreet@xxxxxxxx,fabf@xxxxxxxxx,joe@xxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 06 May 2014 14:51:26 -0700
The patch titled
Subject: Documentation: expand/clarify debug documentation
has been added to the -mm tree. Its filename is
documentation-expand-clarify-debug-documentation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/documentation-expand-clarify-debug-documentation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/documentation-expand-clarify-debug-documentation.patch
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------------------------------------------------------
From: Dan Streetman <ddstreet@xxxxxxxx>
Subject: Documentation: expand/clarify debug documentation
The pr_debug() and related debug print macros all differ from the normal
pr_XXX() macros, in that the normal ones print unconditionally, while the
debug macros are compiled out unless DEBUG is defined or
CONFIG_DYNAMIC_DEBUG is set. This isn't obvious, and the only way to find
this out is either to review the actual printk.h code or to read
CodingStyle, and the message there doesn't highlight the fact.
Change Documentation/CodingStyle to clearly indicate that pr_debug() and
related debug printing macros behave differently than all other pr_XXX()
macros, and attempt to clarify when and where the different debug printing
methods might be used.
Add short comment to printk.h above the pr_XXX() macros indicating that
while these macros print unconditionally, pr_debug() does not.
Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Fabian Frederick <fabf@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/CodingStyle | 22 +++++++++++++++-------
include/linux/printk.h | 6 ++++++
2 files changed, 21 insertions(+), 7 deletions(-)
diff -puN Documentation/CodingStyle~documentation-expand-clarify-debug-documentation Documentation/CodingStyle
--- a/Documentation/CodingStyle~documentation-expand-clarify-debug-documentation
+++ a/Documentation/CodingStyle
@@ -660,15 +660,23 @@ There are a number of driver model diagn
which you should use to make sure messages are matched to the right device
and driver, and are tagged with the right level: dev_err(), dev_warn(),
dev_info(), and so forth. For messages that aren't associated with a
-particular device, <linux/printk.h> defines pr_debug() and pr_info().
+particular device, <linux/printk.h> defines pr_notice(), pr_info(),
+pr_warn(), pr_err(), etc.
Coming up with good debugging messages can be quite a challenge; and once
-you have them, they can be a huge help for remote troubleshooting. Such
-messages should be compiled out when the DEBUG symbol is not defined (that
-is, by default they are not included). When you use dev_dbg() or pr_debug(),
-that's automatic. Many subsystems have Kconfig options to turn on -DDEBUG.
-A related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to the
-ones already enabled by DEBUG.
+you have them, they can be a huge help for remote troubleshooting. However
+debug message printing is handled differently than printing other non-debug
+messages. While the other pr_XXX() functions print unconditionally,
+pr_debug() does not; it is compiled out by default, unless either DEBUG is
+defined or CONFIG_DYNAMIC_DEBUG is set. That is true for dev_dbg() also,
+and a related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to
+the ones already enabled by DEBUG.
+
+Many subsystems have Kconfig debug options to turn on -DDEBUG in the
+corresponding Makefile; in other cases specific files #define DEBUG. And
+when a debug message should be unconditionally printed, such as if it is
+already inside a debug-related #ifdef secton, printk(KERN_DEBUG ...) can be
+used.
Chapter 14: Allocating memory
diff -puN include/linux/printk.h~documentation-expand-clarify-debug-documentation include/linux/printk.h
--- a/include/linux/printk.h~documentation-expand-clarify-debug-documentation
+++ a/include/linux/printk.h
@@ -210,6 +210,12 @@ extern asmlinkage void dump_stack(void)
#define pr_fmt(fmt) fmt
#endif
+/*
+ * These can be used to print at the various log levels.
+ * All of these will print unconditionally, although note that pr_debug()
+ * and other debug macros are compiled out unless either DEBUG is defined
+ * or CONFIG_DYNAMIC_DEBUG is set.
+ */
#define pr_emerg(fmt, ...) \
printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
#define pr_alert(fmt, ...) \
_
Patches currently in -mm which might be from ddstreet@xxxxxxxx are
documentation-expand-clarify-debug-documentation.patch
lib-plistc-replace-pr_debug-with-printk-in-plist_test.patch
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