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 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Alan Stern 2015-11-20 13:53:22 -05:00 • committed by Greg Kroah-Hartman
commit 0290cc9f04
2 changed files with 12 additions and 1 deletions

View file

@ -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).