1 files changed, 71 insertions, 0 deletions
diff --git a/drivers/usb/mon/mon_stat.c b/drivers/usb/mon/mon_stat.c
new file mode 100644
index 000000000..98ab0cc47
--- /dev/null
+++ b/drivers/usb/mon/mon_stat.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is the 's' or 'stat' reader which debugs usbmon itself.
+ * Note that this code blows through locks, so make sure that
+ * /dbg/usbmon/0s is well protected from non-root users.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/usb.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+
+#include "usb_mon.h"
+
+#define STAT_BUF_SIZE  80
+
+struct snap {
+	int slen;
+	char str[STAT_BUF_SIZE];
+};
+
+static int mon_stat_open(struct inode *inode, struct file *file)
+{
+	struct mon_bus *mbus;
+	struct snap *sp;
+
+	sp = kmalloc(sizeof(struct snap), GFP_KERNEL);
+	if (sp == NULL)
+		return -ENOMEM;
+
+	mbus = inode->i_private;
+
+	sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
+	    "nreaders %d events %u text_lost %u\n",
+	    mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
+
+	file->private_data = sp;
+	return 0;
+}
+
+static ssize_t mon_stat_read(struct file *file, char __user *buf,
+				size_t nbytes, loff_t *ppos)
+{
+	struct snap *sp = file->private_data;
+
+	return simple_read_from_buffer(buf, nbytes, ppos, sp->str, sp->slen);
+}
+
+static int mon_stat_release(struct inode *inode, struct file *file)
+{
+	struct snap *sp = file->private_data;
+	file->private_data = NULL;
+	kfree(sp);
+	return 0;
+}
+
+const struct file_operations mon_fops_stat = {
+	.owner =	THIS_MODULE,
+	.open =		mon_stat_open,
+	.llseek =	no_llseek,
+	.read =		mon_stat_read,
+	/* .write =	mon_stat_write, */
+	/* .poll =		mon_stat_poll, */
+	/* .unlocked_ioctl =	mon_stat_ioctl, */
+	.release =	mon_stat_release,
+};