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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:55:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:55:13 -0700
commit00170fdd0846df7cdb5ad421d3a340440f930b8f (patch)
tree1883cfbda846cd65faed011bda54a52c1d40ecdd /Documentation/CodingStyle
parentd09cc3659db494aca4b3bb2393c533fb4946b794 (diff)
parent3ff6db3287e8a5e8f5bb9529b8e1259ca6b10def (diff)
downloadlinux-00170fdd0846df7cdb5ad421d3a340440f930b8f.tar.bz2
Merge branch 'akpm' (patchbomb from Andrew) into next
Merge misc updates from Andrew Morton: - a few fixes for 3.16. Cc'ed to stable so they'll get there somehow. - various misc fixes and cleanups - most of the ocfs2 queue. Review is slow... - most of MM. The MM queue is pretty huge this time, but not much in the way of feature work. - some tweaks under kernel/ - printk maintenance work - updates to lib/ - checkpatch updates - tweaks to init/ * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (276 commits) fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul init/main.c: remove an ifdef kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND init/main.c: add initcall_blacklist kernel parameter init/main.c: don't use pr_debug() fs/binfmt_flat.c: make old_reloc() static fs/binfmt_elf.c: fix bool assignements fs/efs: convert printk(KERN_DEBUG to pr_debug fs/efs: add pr_fmt / use __func__ fs/efs: convert printk to pr_foo() scripts/checkpatch.pl: device_initcall is not the only __initcall substitute checkpatch: check stable email address checkpatch: warn on unnecessary void function return statements checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar); checkpatch: add warning for kmalloc/kzalloc with multiply checkpatch: warn on #defines ending in semicolon checkpatch: make --strict a default for files in drivers/net and net/ checkpatch: always warn on missing blank line after variable declaration block checkpatch: fix wildcard DT compatible string checking ...
Diffstat (limited to 'Documentation/CodingStyle')
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1 files changed, 15 insertions, 7 deletions
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index 7fe0546c504a..6b6bef31e956 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -660,15 +660,23 @@ There are a number of driver model diagnostic macros in <linux/device.h>
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