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authorDaniel Vetter <daniel.vetter@ffwll.ch>2014-07-07 10:17:56 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2014-07-07 10:17:56 +0200
commitf1615bbe9be4def59c3b3eaddb60722efeed16c2 (patch)
treeca3020e65447576fc1826e819651e6ba072030b5 /Documentation/CodingStyle
parentcfb3c0ab0903abb6ea5215b37eebd9c2a1f057eb (diff)
parentcd3de83f147601356395b57a8673e9c5ff1e59d1 (diff)
Merge tag 'v3.16-rc4' into drm-intel-next-queued
Due to Dave's vacation drm-next hasn't opened yet for 3.17 so I couldn't move my drm-intel-next queue forward yet like I usually do. Just pull in the latest upstream -rc to unblock patch merging - I don't want to needlessly rebase my current patch pile really and void all the testing we've done already. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index 7fe0546c504..6b6bef31e95 100644
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@@ -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