bitmap, irq: add smp_affinity_list interface to /proc/irq

Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.

Setting smp affinity to cpus 256 to 263 would be:

	echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity

instead of:

	echo 256-263 > smp_affinity_list

Think about what it looks like for cpus around say, 4088 to 4095.

We already have many alternate "list" interfaces:

/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist

Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps.  This conforms to other companion interfaces where both a map
and a list interface exists.

This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.

[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index bae6fe24d1f9..b24ac56477b4 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -547,6 +547,21 @@ static inline int cpumask_parse_user(const char __user *buf, int len,
 }
 
 /**
+ * cpumask_parselist_user - extract a cpumask from a user string
+ * @buf: the buffer to extract from
+ * @len: the length of the buffer
+ * @dstp: the cpumask to set.
+ *
+ * Returns -errno, or 0 for success.
+ */
+static inline int cpumask_parselist_user(const char __user *buf, int len,
+				     struct cpumask *dstp)
+{
+	return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
+							nr_cpumask_bits);
+}
+
+/**
  * cpulist_scnprintf - print a cpumask into a string as comma-separated list
  * @buf: the buffer to sprintf into
  * @len: the length of the buffer