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

Peter Zijlstra
2012-05-09T15:33:25Z

On Wed, 2012-05-09 at 16:15 +0200, Ingo Molnar wrote:
> > I guess I should use %.*pb and keep the field_width in case someone
> > manages to actually make bitmap_scnlistprintf() conform to it. The
> > precision is unused anyway.
>
> That's a cute trick, and it's intuitive as well.

kernel/sched/core.c:5570:3: warning: precision used with ‘%p’ gnu_printf format [-Wformat]

/me curses a bit.. anybody?

The below compiles and works (with the above caveat) and has all the
style muck people 'wanted'.

---
lib/vsprintf.c | 46 ++++++++++++++++++++++++++++++++--------------
1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index abbabec..6bd9a66 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 */
@@ -857,6 +860,9 @@ 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; %.*pb is required and the precision is used as bitmap length
+ * - '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
@@ -902,24 +908,21 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
* 6: 000102...0f
*/
switch (fmt[1]) {
- case '6':
- return ip6_addr_string(buf, end, ptr, spec, fmt);
- case '4':
- return ip4_addr_string(buf, end, ptr, spec, fmt);
+ case '6': return ip6_addr_string(buf, end, ptr, spec, fmt);
+ case '4': return ip4_addr_string(buf, end, ptr, spec, fmt);
}
break;
case 'U':
return uuid_string(buf, end, ptr, spec, fmt);
- case 'V':
- {
- va_list va;
-
- va_copy(va, *((struct va_format *)ptr)->va);
- buf += vsnprintf(buf, end > buf ? end - buf : 0,
- ((struct va_format *)ptr)->fmt, va);
- va_end(va);
- return buf;
- }
+ case 'V': {
+ va_list va;
+
+ va_copy(va, *((struct va_format *)ptr)->va);
+ buf += vsnprintf(buf, end > buf ? end - buf : 0,
+ ((struct va_format *)ptr)->fmt, va);
+ va_end(va);
+ return buf;
+ }
case 'K':
/*
* %pK cannot be used in IRQ context because its test
@@ -941,6 +944,18 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return netdev_feature_string(buf, end, ptr, spec);
}
break;
+ case 'b': {
+ int bits;
+
+ switch (fmt[1]) {
+ case 'c': bits = nr_cpumask_bits; break;
+ case 'n': bits = MAX_NUMNODES; break;
+ default: bits = spec.precision; break;
+ }
+
+ return buf + bitmap_scnlistprintf(buf, end - buf, ptr, bits);
+ }
+ default: break;
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
@@ -1175,6 +1190,9 @@ int format_decode(const char *fmt, struct printf_spec *spec)
* %pI6c print an IPv6 address as specified by RFC 5952
* %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
* case.
+ * %.*pb print a bitmap list using the precision as bitmap length
+ * %pbc print a cpumask bitmap
+ * %pbn print a nodemask bitmap
* %n is ignored
*
* The return value is the number of characters which would