[RFC][PATCH] printk: Add %pb to print bitmaps

Peter Zijlstra
2012-05-09T13:28:01Z

On Wed, 2012-05-09 at 14:30 +0200, Peter Zijlstra wrote:
> on a related note, we should add a printk-%p modifier for cpulist,
> this cpulist_scnprintf() stuff gets annoying.

Something like so I guess.. I'll try and convert some of the sched_debug
code to test it..

---
lib/vsprintf.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index abbabec..90bfcd1 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,9 @@
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
+#include <linux/bitmap.h>
+#include <linux/cpumask.h>
+#include <linux/numa.h>
#include <net/addrconf.h>

#include <asm/page.h> /* for PAGE_SIZE */
@@ -857,15 +860,19 @@ int kptr_restrict __read_mostly;
* correctness of the format string and va_list arguments.
* - 'K' For a kernel pointer that should be hidden from unprivileged users
* - 'NF' For a netdev_features_t
+ * - 'b' For a bitmap, consumes 2 args, second is int
+ * - 'bc' For a cpumask
+ * - 'bn' For a nodemask
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
* pointer to the real address.
*/
-static noinline_for_stack
-char *pointer(const char *fmt, char *buf, char *end, void *ptr,
- struct printf_spec spec)
+static noinline_for_stack
+char *pointer(const char *fmt, char *buf, char *end, va_list args, struct printf_spec spec)
{
+ void *ptr = va_arg(args, void *);
+
if (!ptr && *fmt != 'K') {
/*
* Print (null) with the same width as a pointer so it makes
@@ -941,6 +948,26 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return netdev_feature_string(buf, end, ptr, spec);
}
break;
+ case 'b':
+ {
+ int bits, len;
+
+ switch (fmt[1]) {
+ case 'c':
+ bits = nr_cpumask_bits;
+ break;
+ case 'n':
+ bits = MAX_NUMNODES;
+ break;
+ default:
+ bits = va_arg(args, int);
+ break;
+ }
+
+ len = bitmap_scnlistprintf(buf, end - buf, ptr, bits);
+
+ return buf + len;
+ }
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
@@ -1261,8 +1288,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
break;

case FORMAT_TYPE_PTR:
- str = pointer(fmt+1, str, end, va_arg(args, void *),
- spec);
+ str = pointer(fmt+1, str, end, args, spec);
while (isalnum(*fmt))
fmt++;
break;