taskset: support CPU masks for more than 64 CPUs

function                                             old     new   delta
taskset_main                                         522     631    +109

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 79 insertions, 7 deletions

diff --git a/miscutils/taskset.c b/miscutils/taskset.c
index 4a9e323..8bd32ed 100644
--- a/miscutils/taskset.c
+++ b/miscutils/taskset.c
@@ -6,6 +6,25 @@
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
+//config:config TASKSET
+//config:	bool "taskset"
+//config:	default n  # doesn't build on some non-x86 targets (m68k)
+//config:	help
+//config:	  Retrieve or set a processes's CPU affinity.
+//config:	  This requires sched_{g,s}etaffinity support in your libc.
+//config:
+//config:config FEATURE_TASKSET_FANCY
+//config:	bool "Fancy output"
+//config:	default y
+//config:	depends on TASKSET
+//config:	help
+//config:	  Add code for fancy output. This merely silences a compiler-warning
+//config:	  and adds about 135 Bytes. May be needed for machines with alot
+//config:	  of CPUs.
+
+//applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
+//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
+
 //usage:#define taskset_trivial_usage
 //usage:       "[-p] [MASK] [PID | PROG ARGS]"
 //usage:#define taskset_full_usage "\n\n"
@@ -22,6 +41,11 @@
 //usage:       "pid 6671's new affinity mask: 1\n"
 //usage:       "$ taskset -p 1\n"
 //usage:       "pid 1's current affinity mask: 3\n"
+/*
+ Not yet implemented:
+ * -a/--all-tasks (affect all threads)
+ * -c/--cpu-list  (specify CPUs via "1,3,5-7")
+ */
 
 #include <sched.h>
 #include "libbb.h"
@@ -128,17 +152,65 @@ int taskset_main(int argc UNUSED_PARAM, char **argv)
 		current_new += 8; /* "new" */
 	}
 
-	{ /* Affinity was specified, translate it into cpu_set_t */
+	/* Affinity was specified, translate it into cpu_set_t */
+	CPU_ZERO(&mask);
+	if (!ENABLE_FEATURE_TASKSET_FANCY) {
 		unsigned i;
+		unsigned long long m;
+
 		/* Do not allow zero mask: */
-		unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
-		enum { CNT_BIT = CPU_SETSIZE < sizeof(m)*8 ? CPU_SETSIZE : sizeof(m)*8 };
+		m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
+		i = 0;
+		do {
+			if (m & 1)
+				CPU_SET(i, &mask);
+			i++;
+			m >>= 1;
+		} while (m != 0);
+	} else {
+		unsigned i;
+		char *last_byte;
+		char *bin;
+		uint8_t bit_in_byte;
+
+		/* Cheap way to get "long enough" buffer */
+		bin = xstrdup(aff);
+
+		if (aff[0] != '0' && (aff[1]|0x20) != 'x') {
+/* TODO: decimal/octal masks are still limited to 2^64 */
+			unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
+			bin += strlen(bin);
+			last_byte = bin - 1;
+			while (m) {
+				*--bin = m & 0xff;
+				m >>= 8;
+			}
+		} else {
+			/* aff is "0x.....", we accept very long masks in this form */
+			last_byte = hex2bin(bin, aff + 2, INT_MAX);
+			if (!last_byte) {
+ bad_aff:
+				bb_error_msg_and_die("bad affinity '%s'", aff);
+			}
+			last_byte--; /* now points to the last byte */
+		}
 
-		CPU_ZERO(&mask);
-		for (i = 0; i < CNT_BIT; i++) {
-			unsigned long long bit = (1ULL << i);
-			if (bit & m)
+		i = 0;
+		bit_in_byte = 1;
+		while (last_byte >= bin) {
+			if (bit_in_byte & *last_byte) {
+				if (i >= CPU_SETSIZE)
+					goto bad_aff;
 				CPU_SET(i, &mask);
+				//bb_error_msg("bit %d set", i);
+			}
+			i++;
+			/* bit_in_byte is uint8_t! & 0xff is implied */
+			bit_in_byte = (bit_in_byte << 1);
+			if (!bit_in_byte) {
+				bit_in_byte = 1;
+				last_byte--;
+			}
 		}
 	}