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Date: Sat, 2 Aug 2008 15:28:28 +0400
From: Alexey Dobriyan <adobriyan@...il.com>
To: akpm@...l.org
Cc: pj@....com, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] Add seq_cpumask(), seq_nodemask()
Short enough reads from /proc/irq/*/smp_affinity return -EINVAL
for no good reason.
This became noticed with NR_CPUS=4096 patches, when length of printed
representation of cpumask becase 1152, but cat(1) continued to read with
1024-byte chunks. bitmap_scnprintf() in good faith fills buffer, returns
1023, check returns -EINVAL.
Fix it by switching to seq_file, so handler will just fill buffer and
doesn't care about offsets, length, filling EOF and all this crap.
For that add seq_bitmap(), and wrappers around it -- seq_cpumask() and
seq_nodemask().
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
fs/seq_file.c | 14 ++++++++++++++
include/linux/bitmap.h | 1 +
include/linux/seq_file.h | 12 ++++++++++++
lib/bitmap.c | 11 +++++++++++
4 files changed, 38 insertions(+)
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -443,6 +443,20 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
return -1;
}
+int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
+{
+ size_t len = bitmap_scnprintf_len(nr_bits);
+
+ if (m->count + len < m->size) {
+ bitmap_scnprintf(m->buf + m->count, m->size - m->count,
+ bits, nr_bits);
+ m->count += len;
+ return 0;
+ }
+ m->count = m->size;
+ return -1;
+}
+
static void *single_start(struct seq_file *p, loff_t *pos)
{
return NULL + (*pos == 0);
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -110,6 +110,7 @@ extern int __bitmap_weight(const unsigned long *bitmap, int bits);
extern int bitmap_scnprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits);
+extern int bitmap_scnprintf_len(unsigned int nr_bits);
extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
unsigned long *dst, int nbits);
extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -4,6 +4,8 @@
#include <linux/types.h>
#include <linux/string.h>
#include <linux/mutex.h>
+#include <linux/cpumask.h>
+#include <linux/nodemask.h>
struct seq_operations;
struct file;
@@ -47,6 +49,16 @@ int seq_path(struct seq_file *, struct path *, char *);
int seq_dentry(struct seq_file *, struct dentry *, char *);
int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
char *esc);
+int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits);
+static inline int seq_cpumask(struct seq_file *m, cpumask_t *mask)
+{
+ return seq_bitmap(m, mask->bits, NR_CPUS);
+}
+
+static inline int seq_nodemask(struct seq_file *m, nodemask_t *mask)
+{
+ return seq_bitmap(m, mask->bits, MAX_NUMNODES);
+}
int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
int single_release(struct inode *, struct file *);
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -316,6 +316,17 @@ int bitmap_scnprintf(char *buf, unsigned int buflen,
EXPORT_SYMBOL(bitmap_scnprintf);
/**
+ * bitmap_scnprintf_len - return buffer length needed to convert
+ * bitmap to an ASCII hex string
+ * @nr_bits: number of bits to be converted
+ */
+int bitmap_scnprintf_len(unsigned int nr_bits)
+{
+ unsigned int nr_nibbles = ALIGN(nr_bits, 4) / 4;
+ return nr_nibbles + ALIGN(nr_nibbles, CHUNKSZ / 4) / (CHUNKSZ / 4) - 1;
+}
+
+/**
* __bitmap_parse - convert an ASCII hex string into a bitmap.
* @buf: pointer to buffer containing string.
* @buflen: buffer size in bytes. If string is smaller than this
--
1.5.3.7
--
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