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Commit 50ac2d69 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
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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: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: default avatarPaul Jackson <pj@sgi.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dd763460

fs/seq_file.c

+14 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/bitmap.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

include/linux/seq_file.h

+12 −0
Original line number Diff line number Diff line
@@ -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 *);

lib/bitmap.c

+11 −0
Original line number Diff line number Diff line
@@ -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.