introduce banirq option

Fixing bug http://code.google.com/p/irqbalance/issues/detail?id=25

It was pointed out that during the rewrite of irqbalance I inadvertently removed
the support for the IRQBALANCE_BANNED_IRQS environment variable. While going to
return it to the build, it occured to me that, given the availability of msi[x]
irqs, a single system can literally have thousands of interrupt sources, making
the environment variable a non-scalable solution.  Instead I'm adding a new
option, banirqs, which takes its place.  It lets you build a list of irqs that
you want irqbalance to leave alone.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

classify.c

@@ -52,6 +52,7 @@ static short class_codes[MAX_CLASS] = {
 };
 
 static GList *interrupts_db;
+static GList *banned_irqs;
 
 #define SYSDEV_DIR "/sys/bus/pci/devices"
 
@@ -63,6 +64,30 @@ static gint compare_ints(gconstpointer a, gconstpointer b)
 	return ai->irq - bi->irq;
 }
 
+void add_banned_irq(int irq)
+{
+	struct irq_info find, *new;
+	GList *entry;
+
+	find.irq = irq;
+	entry = g_list_find_custom(banned_irqs, &find, compare_ints);
+	if (entry)
+		return;
+
+	new = calloc(sizeof(struct irq_info), 1);
+	if (!new) {
+		if (debug_mode)
+			printf("No memory to ban irq %d\n", irq);
+		return;
+	}
+
+	new->irq = irq;
+
+	banned_irqs = g_list_append(banned_irqs, new);
+	return;
+}
+
+			
 /*
  * Inserts an irq_info struct into the intterupts_db list
  * devpath points to the device directory in sysfs for the 
@@ -90,6 +115,13 @@ static struct irq_info *add_one_irq_to_db(const char *devpath, int irq)
 		return NULL;
 	}
 
+	entry = g_list_find_custom(banned_irqs, &find, compare_ints);
+	if (entry) {
+		if (debug_mode)
+			printf("SKIPPING BANNED IRQ %d\n", irq);
+		return NULL;
+	}
+
 	new = calloc(sizeof(struct irq_info), 1);
 	if (!new)
 		return NULL;

irqbalance.1

@@ -66,6 +66,13 @@ average cpu softirq workload, and no cpus are more than 1 standard deviation
 above (and have more than 1 irq assigned to them), attempt to place 1 cpu in
 powersave mode.  In powersave mode, a cpu will not have any irqs balanced to it,
 in an effort to prevent that cpu from waking up without need.
+
+.TP
+.B --banirq=<irqnum>
+Add the specified irq list to the set of banned irqs. irqbalance will not affect
+the affinity of any irqs on the banned list, allowing them to be specified
+manually.  This option is addative and can be specified multiple times
+
 .SH "ENVIRONMENT VARIABLES"
 .TP
 .B IRQBALANCE_ONESHOT
@@ -79,10 +86,6 @@ Same as --debug
 .B IRQBALANCE_BANNED_CPUS
 Provides a mask of cpus which irqbalance should ignore and never assign interrupts to
 
-.TP
-.B IRQBALANCE_BANNED_INTERRUPTS
-A list of space delimited IRQ numbers that irqbalance should not touch
-
 .SH "Homepage"
 http://code.google.com/p/irqbalance
 

irqbalance.c

@@ -68,22 +68,24 @@ struct option lopts[] = {
 	{"foreground", 0, NULL, 'f'},
 	{"hintpolicy", 1, NULL, 'h'},
 	{"powerthresh", 1, NULL, 'p'},
+	{"banirq", 1 , NULL, 'i'},
 	{0, 0, 0, 0}
 };
 
 static void usage(void)
 {
 	printf("irqbalance [--oneshot | -o] [--debug | -d] [--foreground | -f] [--hintpolicy= | -h [exact|subset|ignore]]\n");
-	printf("	[--powerthresh= | -p <off> | <n>]\n");
+	printf("	[--powerthresh= | -p <off> | <n>] [--banirq= | -i <n>]\n");
 }
 
 static void parse_command_line(int argc, char **argv)
 {
 	int opt;
 	int longind;
+	unsigned long val;
 
 	while ((opt = getopt_long(argc, argv,
-		"odfh:p:",
+		"odfh:i:p:",
 		lopts, &longind)) != -1) {
 
 		switch(opt) {
@@ -109,6 +111,14 @@ static void parse_command_line(int argc, char **argv)
 					exit(1);
 				}
 				break;
+			case 'i':
+				val = strtoull(optarg, NULL, 10);
+				if (val == ULONG_MAX) {
+					usage();
+					exit(1);
+				}
+				add_banned_irq((int)val);
+				break;
 			case 'p':
 				if (!strncmp(optarg, "off", strlen(optarg)))
 					power_thresh = ULONG_MAX;

irqbalance.h

@@ -103,6 +103,7 @@ extern int get_cpu_count(void);
  */
 extern void rebuild_irq_db(void);
 extern void free_irq_db(void);
+extern void add_banned_irq(int irq);
 extern void for_each_irq(GList *list, void (*cb)(struct irq_info *info,  void *data), void *data);
 extern struct irq_info *get_irq_info(int irq);
 extern void migrate_irq(GList **from, GList **to, struct irq_info *info);