tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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>

authored by

Alexey Dobriyan and committed by
Linus Torvalds 50ac2d69 dd763460

+38
+14
fs/seq_file.c
··· 443 443 return -1; 444 444 } 445 445 446 + int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits) 447 + { 448 + size_t len = bitmap_scnprintf_len(nr_bits); 449 + 450 + if (m->count + len < m->size) { 451 + bitmap_scnprintf(m->buf + m->count, m->size - m->count, 452 + bits, nr_bits); 453 + m->count += len; 454 + return 0; 455 + } 456 + m->count = m->size; 457 + return -1; 458 + } 459 + 446 460 static void *single_start(struct seq_file *p, loff_t *pos) 447 461 { 448 462 return NULL + (*pos == 0);
+1
include/linux/bitmap.h
··· 110 110 111 111 extern int bitmap_scnprintf(char *buf, unsigned int len, 112 112 const unsigned long *src, int nbits); 113 + extern int bitmap_scnprintf_len(unsigned int nr_bits); 113 114 extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user, 114 115 unsigned long *dst, int nbits); 115 116 extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
+12
include/linux/seq_file.h
··· 4 4 #include <linux/types.h> 5 5 #include <linux/string.h> 6 6 #include <linux/mutex.h> 7 + #include <linux/cpumask.h> 8 + #include <linux/nodemask.h> 7 9 8 10 struct seq_operations; 9 11 struct file; ··· 49 47 int seq_dentry(struct seq_file *, struct dentry *, char *); 50 48 int seq_path_root(struct seq_file *m, struct path *path, struct path *root, 51 49 char *esc); 50 + int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits); 51 + static inline int seq_cpumask(struct seq_file *m, cpumask_t *mask) 52 + { 53 + return seq_bitmap(m, mask->bits, NR_CPUS); 54 + } 55 + 56 + static inline int seq_nodemask(struct seq_file *m, nodemask_t *mask) 57 + { 58 + return seq_bitmap(m, mask->bits, MAX_NUMNODES); 59 + } 52 60 53 61 int single_open(struct file *, int (*)(struct seq_file *, void *), void *); 54 62 int single_release(struct inode *, struct file *);
+11
lib/bitmap.c
··· 316 316 EXPORT_SYMBOL(bitmap_scnprintf); 317 317 318 318 /** 319 + * bitmap_scnprintf_len - return buffer length needed to convert 320 + * bitmap to an ASCII hex string 321 + * @nr_bits: number of bits to be converted 322 + */ 323 + int bitmap_scnprintf_len(unsigned int nr_bits) 324 + { 325 + unsigned int nr_nibbles = ALIGN(nr_bits, 4) / 4; 326 + return nr_nibbles + ALIGN(nr_nibbles, CHUNKSZ / 4) / (CHUNKSZ / 4) - 1; 327 + } 328 + 329 + /** 319 330 * __bitmap_parse - convert an ASCII hex string into a bitmap. 320 331 * @buf: pointer to buffer containing string. 321 332 * @buflen: buffer size in bytes. If string is smaller than this