Merge branch 'x86-asm-generic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / Documentation / s390 / s390dbf.txt

diff --git a/Documentation/s390/s390dbf.txt b/Documentation/s390/s390dbf.txt
index e054209..ae66f9b 100644 (file)
--- a/Documentation/s390/s390dbf.txt
+++ b/Documentation/s390/s390dbf.txt
@@ -2,7 +2,7 @@ S390 Debug Feature
 ==================
 
 files: arch/s390/kernel/debug.c
-       include/asm-s390/debug.h
+       arch/s390/include/asm/debug.h
 
 Description:
 ------------
@@ -495,6 +495,13 @@ and for each vararg a long value. So e.g. for a debug entry with a format
 string plus two varargs one would need to allocate a (3 * sizeof(long)) 
 byte data area in the debug_register() function.
 
+IMPORTANT: Using "%s" in sprintf event functions is dangerous. You can only
+use "%s" in the sprintf event functions, if the memory for the passed string is
+available as long as the debug feature exists. The reason behind this is that
+due to performance considerations only a pointer to the string is stored in
+the debug feature. If you log a string that is freed afterwards, you will get
+an OOPS when inspecting the debug feature, because then the debug feature will
+access the already freed memory.
 
 NOTE: If using the sprintf view do NOT use other event/exception functions
 than the sprintf-event and -exception functions.