1 files changed, 97 insertions, 4 deletions

diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index a49a31639f6f..d36f3b6992bb 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -68,9 +68,102 @@ MODULE_AUTHOR("Matthew Dharm <mdharm-usb@one-eyed-alien.net>");
 MODULE_DESCRIPTION("USB Mass Storage driver for Linux");
 MODULE_LICENSE("GPL");
 
-static unsigned int delay_use = 1;
-module_param(delay_use, uint, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(delay_use, "seconds to delay before using a new device");
+static unsigned int delay_use = 1 * MSEC_PER_SEC;
+
+/**
+ * parse_delay_str - parse an unsigned decimal integer delay
+ * @str: String to parse.
+ * @ndecimals: Number of decimal to scale up.
+ * @suffix: Suffix string to parse.
+ * @val: Where to store the parsed value.
+ *
+ * Parse an unsigned decimal value in @str, optionally end with @suffix.
+ * Stores the parsed value in @val just as it is if @str ends with @suffix.
+ * Otherwise store the value scale up by 10^(@ndecimal).
+ *
+ * Returns 0 on success, a negative error code otherwise.
+ */
+static int parse_delay_str(const char *str, int ndecimals, const char *suffix,
+			unsigned int *val)
+{
+	int n, n2, l;
+	char buf[16];
+
+	l = strlen(suffix);
+	n = strlen(str);
+	if (n > 0 && str[n - 1] == '\n')
+		--n;
+	if (n >= l && !strncmp(&str[n - l], suffix, l)) {
+		n -= l;
+		n2 = 0;
+	} else
+		n2 = ndecimals;
+
+	if (n + n2 > sizeof(buf) - 1)
+		return -EINVAL;
+
+	memcpy(buf, str, n);
+	while (n2-- > 0)
+		buf[n++] = '0';
+	buf[n] = 0;
+
+	return kstrtouint(buf, 10, val);
+}
+
+/**
+ * format_delay_ms - format an integer value into a delay string
+ * @val: The integer value to format, scaled by 10^(@ndecimals).
+ * @ndecimals: Number of decimal to scale down.
+ * @suffix: Suffix string to format.
+ * @str: Where to store the formatted string.
+ * @size: The size of buffer for @str.
+ *
+ * Format an integer value in @val scale down by 10^(@ndecimals) without @suffix
+ * if @val is divisible by 10^(@ndecimals).
+ * Otherwise format a value in @val just as it is with @suffix
+ *
+ * Returns the number of characters written into @str.
+ */
+static int format_delay_ms(unsigned int val, int ndecimals, const char *suffix,
+			char *str, int size)
+{
+	u64 delay_ms = val;
+	unsigned int rem = do_div(delay_ms, int_pow(10, ndecimals));
+	int ret;
+
+	if (rem)
+		ret = scnprintf(str, size, "%u%s\n", val, suffix);
+	else
+		ret = scnprintf(str, size, "%u\n", (unsigned int)delay_ms);
+	return ret;
+}
+
+static int delay_use_set(const char *s, const struct kernel_param *kp)
+{
+	unsigned int delay_ms;
+	int ret;
+
+	ret = parse_delay_str(skip_spaces(s), 3, "ms", &delay_ms);
+	if (ret < 0)
+		return ret;
+
+	*((unsigned int *)kp->arg) = delay_ms;
+	return 0;
+}
+
+static int delay_use_get(char *s, const struct kernel_param *kp)
+{
+	unsigned int delay_ms = *((unsigned int *)kp->arg);
+
+	return format_delay_ms(delay_ms, 3, "ms", s, PAGE_SIZE);
+}
+
+static const struct kernel_param_ops delay_use_ops = {
+	.set = delay_use_set,
+	.get = delay_use_get,
+};
+module_param_cb(delay_use, &delay_use_ops, &delay_use, 0644);
+MODULE_PARM_DESC(delay_use, "time to delay before using a new device");
 
 static char quirks[128];
 module_param_string(quirks, quirks, sizeof(quirks), S_IRUGO | S_IWUSR);
@@ -1064,7 +1157,7 @@ int usb_stor_probe2(struct us_data *us)
 	if (delay_use > 0)
 		dev_dbg(dev, "waiting for device to settle before scanning\n");
 	queue_delayed_work(system_freezable_wq, &us->scan_dwork,
-			delay_use * HZ);
+			msecs_to_jiffies(delay_use));
 	return 0;
 
 	/* We come here if there are any problems */