cpumask: Omit terminating null byte in cpumap_print_{list,bitmask}_to_buf

The changes in the patch series [1] introduced a terminating null byte
when reading from cpulist or cpumap sysfs files, for example:

  $ xxd /sys/devices/system/node/node0/cpulist
  00000000: 302d 310a 00                             0-1..

Before this change, the output looked as follows:

  $ xxd /sys/devices/system/node/node0/cpulist
  00000000: 302d 310a                                0-1.

Fix this regression by excluding the terminating null byte from the
returned length in cpumap_print_list_to_buf and
cpumap_print_bitmask_to_buf.

[1] https://lore.kernel.org/all/[email protected]/

Fixes: 1fae562 ("cpumask: introduce cpumap_print_list/bitmask_to_buf to support large bitmask and list")
Acked-by: Barry Song <[email protected]>
Acked-by: Yury Norov <[email protected]>
Signed-off-by: Tobias Klauser <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: tklauser

include/linux/cpumask.h

@@ -996,14 +996,15 @@ cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
  * cpumask; Typically used by bin_attribute to export cpumask bitmask
  * ABI.
  *
- * Returns the length of how many bytes have been copied.
+ * Returns the length of how many bytes have been copied, excluding
+ * terminating '\0'.
  */
 static inline ssize_t
 cpumap_print_bitmask_to_buf(char *buf, const struct cpumask *mask,
 		loff_t off, size_t count)
 {
 	return bitmap_print_bitmask_to_buf(buf, cpumask_bits(mask),
-				   nr_cpu_ids, off, count);
+				   nr_cpu_ids, off, count) - 1;
 }
 
 /**
@@ -1018,7 +1019,7 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
 		loff_t off, size_t count)
 {
 	return bitmap_print_list_to_buf(buf, cpumask_bits(mask),
-				   nr_cpu_ids, off, count);
+				   nr_cpu_ids, off, count) - 1;
 }
 
 #if NR_CPUS <= BITS_PER_LONG