irq: break out from xutils and save + restore

Break out IRQ functionality from xutils, simplify it, and
save + restore IRQ affinity list.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

1 files changed, 129 insertions, 0 deletions

diff --git a/irq.c b/irq.c
new file mode 100644
index 0000000..fbd1cbc
--- /dev/null
+++ b/irq.c
@@ -0,0 +1,129 @@
+/*
+ * netsniff-ng - the packet sniffing beast
+ * Copyright 2009 - 2013 Daniel Borkmann.
+ * Copyright 2009, 2010 Emmanuel Roullit.
+ * Subject to the GPL, version 2.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "irq.h"
+#include "die.h"
+#include "xutils.h"
+
+int device_irq_number(const char *ifname)
+{
+	int irq = 0;
+	char buff[128], sysname[128];
+	FILE *fp;
+
+	if (!strncmp("lo", ifname, strlen("lo")))
+		return 0;
+
+	slprintf(sysname, sizeof(sysname),
+		 "/sys/class/net/%s/device/irq",
+		 ifname);
+
+	fp = fopen(sysname, "r");
+	if (!fp)
+		return -ENOENT;
+
+	memset(buff, 0, sizeof(buff));
+
+	if (fgets(buff, sizeof(buff), fp) != NULL) {
+		buff[sizeof(buff) - 1] = 0;
+		irq = atoi(buff);
+	}
+
+	fclose(fp);
+	return irq;
+}
+
+static char nic_irq_affinity_list[128];
+static bool nic_irq_stored = false;
+static int  nic_irq = -1;
+
+static void device_save_irq_affinity_list(void)
+{
+	int ret, fd;
+	char file[128];
+
+	bug_on(nic_irq_stored);
+
+	slprintf(file, sizeof(file),
+		 "/proc/irq/%d/smp_affinity_list", nic_irq);
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0)
+		return;
+
+	memset(nic_irq_affinity_list, 0, sizeof(nic_irq_affinity_list));
+
+	ret = read(fd, nic_irq_affinity_list,
+		   sizeof(nic_irq_affinity_list));
+	if (ret < 0)
+		panic("Cannot store NIC IRQ affinity!\n");
+
+	close(fd);
+
+	nic_irq_stored = true;
+}
+
+void device_restore_irq_affinity_list(void)
+{
+	int ret, fd;
+	char file[128];
+
+	if (!nic_irq_stored)
+		return;
+
+	bug_on(nic_irq == -1);
+
+	slprintf(file, sizeof(file),
+		 "/proc/irq/%d/smp_affinity_list", nic_irq);
+
+	fd = open(file, O_WRONLY);
+	if (fd < 0)
+		return;
+
+	ret = write(fd, nic_irq_affinity_list,
+		    sizeof(nic_irq_affinity_list));
+	if (ret < 0)
+		panic("Cannot restore NIC IRQ affinity!\n");
+
+	close(fd);
+}
+
+int device_set_irq_affinity_list(int irq, unsigned long from, unsigned long to)
+{
+	int ret, fd;
+	char file[128], list[64];
+
+	if (!nic_irq_stored) {
+		nic_irq = irq;
+		device_save_irq_affinity_list();
+	}
+
+	slprintf(file, sizeof(file), "/proc/irq/%d/smp_affinity_list", irq);
+	slprintf(list, sizeof(list), "%lu-%lu\n", from, to);
+
+	fd = open(file, O_WRONLY);
+	if (fd < 0)
+		return -ENOENT;
+
+	ret = write(fd, list, strlen(list));
+
+	close(fd);
+	return ret;
+}
+
+int device_bind_irq_to_cpu(int irq, int cpu)
+{
+	return device_set_irq_affinity_list(irq, cpu, cpu);
+}