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seq_file: 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@gmail.com>
Reviewed-by: Paul Jackson <pj@sgi.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2008-08-12 15:09:02 -07:00 committed by Linus Torvalds
parent dd763460eb
commit 50ac2d694f
4 changed files with 38 additions and 0 deletions
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14
fs/seq_file.c
View File

@ -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);

1
include/linux/bitmap.h
View File

@ -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,

12
include/linux/seq_file.h
View File

@ -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 *);

11
lib/bitmap.c
View File

@ -315,6 +315,17 @@ 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.