[PATCH] get_options to allow a hypenated range for isolcpus

This allows a hyphenated range of positive numbers in the string passed
to command line helper function, get_options.

Currently the command line option "isolcpus=" takes as its argument a
list of cpus.

Format: <cpu number>,...,<cpu number>
Valid values of <cpu_number>  include all cpus, 0 to "number of CPUs in
system - 1". This can get extremely long when isolating the majority of
cpus on a large system.  The kernel isolcpus code would not need any
changing to use this feature.  To use it, the change would be in the
command line format for 'isolcpus='
Format:
<cpu number>,...,<cpu number>
or
<cpu number>-<cpu number>  (must be a positive range in ascending
order.)
or a mixture
<cpu number>,...,<cpu number>-<cpu number>

Signed-off-by: Derek Fults <dfults@sgi.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1e183bd33d71f3c578a4e2f52966af2b3eab41c4..8fe6b834ef2701a876141fc22d1ef9c9b157bf90 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -714,7 +714,12 @@ and is between 256 and 4096 characters. It is defined in the file
                        Format: <RDP>,<reset>,<pci_scan>,<verbosity>
 
        isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
-                       Format: <cpu number>,...,<cpu number>
+                       Format:
+                       <cpu number>,...,<cpu number>
+                       or
+                       <cpu number>-<cpu number>  (must be a positive range in ascending order)
+                       or a mixture
+                       <cpu number>,...,<cpu number>-<cpu number>
                        This option can be used to specify one or more CPUs
                        to isolate from the general SMP balancing and scheduling
                        algorithms. The only way to move a process onto or off

diff --git a/lib/cmdline.c b/lib/cmdline.c
index 0331ed825ea79e568a881852020a80adc3d4d658..8a5b5303bd4f7a78187b4138eb08945c6333c10c 100644 (file)
--- a/lib/cmdline.c
+++ b/lib/cmdline.c
@@ -16,6 +16,23 @@
 #include <linux/kernel.h>
 #include <linux/string.h>
 
+/*
+ *     If a hyphen was found in get_option, this will handle the
+ *     range of numbers, M-N.  This will expand the range and insert
+ *     the values[M, M+1, ..., N] into the ints array in get_options.
+ */
+
+static int get_range(char **str, int *pint)
+{
+       int x, inc_counter, upper_range;
+
+       (*str)++;
+       upper_range = simple_strtol((*str), NULL, 0);
+       inc_counter = upper_range - *pint;
+       for (x = *pint; x < upper_range; x++)
+               *pint++ = x;
+       return inc_counter;
+}
 
 /**
  *     get_option - Parse integer from an option string
@@ -29,6 +46,7 @@
  *     0 : no int in string
  *     1 : int found, no subsequent comma
  *     2 : int found including a subsequent comma
+ *     3 : hyphen found to denote a range
  */
 
 int get_option (char **str, int *pint)
@@ -44,6 +62,8 @@ int get_option (char **str, int *pint)
                (*str)++;
                return 2;
        }
+       if (**str == '-')
+               return 3;
 
        return 1;
 }
@@ -55,7 +75,8 @@ int get_option (char **str, int *pint)
  *     @ints: integer array
  *
  *     This function parses a string containing a comma-separated
- *     list of integers.  The parse halts when the array is
+ *     list of integers, a hyphen-separated range of _positive_ integers,
+ *     or a combination of both.  The parse halts when the array is
  *     full, or when no more numbers can be retrieved from the
  *     string.
  *
@@ -72,6 +93,18 @@ char *get_options(const char *str, int nints, int *ints)
                res = get_option ((char **)&str, ints + i);
                if (res == 0)
                        break;
+               if (res == 3) {
+                       int range_nums;
+                       range_nums = get_range((char **)&str, ints + i);
+                       if (range_nums < 0)
+                               break;
+                       /*
+                        * Decrement the result by one to leave out the
+                        * last number in the range.  The next iteration
+                        * will handle the upper number in the range
+                        */
+                       i += (range_nums - 1);
+               }
                i++;
                if (res == 1)
                        break;