From 0290cc9f044a4d24d9a64e81761ac84498dc9d73 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 20 Nov 2015 13:53:22 -0500 Subject: [PATCH] USB: limit usbfs snooping of URB contents The usbfs_snoop facility can be very useful for debugging problems involving usbfs. However, it always prints out the entire contents of every URB. When dealing with large quantities of data, this can be less than helpful. This patch ameliorates the situation by adding a module parameter to usbcore for controlling the maximum number of bytes to print when snooping an URB. This makes debugging much easier. For backward compatibility, the default value is set unreasonably high. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- Documentation/kernel-parameters.txt | 4 ++++ drivers/usb/core/devio.c | 9 ++++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 742f69d18fc8..e6b6e056cc11 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3874,6 +3874,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. usbcore.usbfs_snoop= [USB] Set to log all usbfs traffic (default 0 = off). + usbcore.usbfs_snoop_max= + [USB] Maximum number of bytes to snoop in each URB + (default = 65536). + usbcore.blinkenlights= [USB] Set to cycle leds on hubs (default 0 = off). diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 38ae877c46e3..3d41faf6e607 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -100,6 +100,11 @@ static bool usbfs_snoop; module_param(usbfs_snoop, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(usbfs_snoop, "true to log all usbfs traffic"); +static unsigned usbfs_snoop_max = 65536; +module_param(usbfs_snoop_max, uint, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(usbfs_snoop_max, + "maximum number of bytes to print while snooping"); + #define snoop(dev, format, arg...) \ do { \ if (usbfs_snoop) \ @@ -392,6 +397,7 @@ static void snoop_urb(struct usb_device *udev, ep, t, d, length, timeout_or_status); } + data_len = min(data_len, usbfs_snoop_max); if (data && data_len > 0) { print_hex_dump(KERN_DEBUG, "data: ", DUMP_PREFIX_NONE, 32, 1, data, data_len, 1); @@ -402,7 +408,8 @@ static void snoop_urb_data(struct urb *urb, unsigned len) { int i, size; - if (!usbfs_snoop) + len = min(len, usbfs_snoop_max); + if (!usbfs_snoop || len == 0) return; if (urb->num_sgs == 0) { -- 2.20.1