Vojtech Pavlik wrote:
On Sun, Nov 28, 2004 at 11:03:11PM +0100, Manfred Spraul wrote:
Hi pavel,
My name is Vojtech. ;)
Up, sorry.
CHECK_OWNERSHIP in drivers/usb/input/hid-tmff.c tests for current->pid==0. The same code is used in several files (hid-lgff.c, usb/input/pid.c, drivers/input/joystick/iforce/iforce.h)
Do you know why? I don't understand the reason for the test.
There are two cases where current->pid is 0: for the idle thread(s) and historically for dead threads (not true anymore). current can't be dead and I don't think that it makes sense to check if current is an idle thread.
I think it's to check whether there is a process associated with the device, with 0 being a special value "no process".
So the USB layer overwrites current->pid? Are you sure?
The actual test is
#define CHECK_OWNERSHIP(effect) (current->pid == 0 \
|| effect.owner == current->pid)Note that it's current->pid==0, not effect.owner==0.
-- Manfred
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