From: Marcin Slusarz Date: Mon, 12 May 2008 18:17:25 +0000 (+0200) Subject: usbtest: comment on why this code "expects" negative and positive errnos X-Git-Tag: firefly_0821_release~20318^2~2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6def755320a214ae149ad6bc69eb8c1d7887e678;p=firefly-linux-kernel-4.4.55.git usbtest: comment on why this code "expects" negative and positive errnos On Mon, May 12, 2008 at 01:02:22AM -0700, David Brownell wrote: > On Sunday 11 May 2008, Marcin Slusarz wrote: > > > > test_ctrl_queue expects (?) positive and negative errnos. > > what is going on here? > > The sign is just a way to flag something: > > /* some faults are allowed, not required */ > > The negative ones are required. Positive codes are optional, > in the sense that, depending on how the peripheral happens > to be implemented, they won't necessarily be triggered. > > For example, the test to fetch a device qualifier desriptor > must succeed if the device is running at high speed. So that > test is marked as negative. But when it's full speed, it > could legitimately fail; marked as positive. And so on for > other tests. > > Look at how the codes are *interpreted* to see it work. Lets document it. Based on comment from David Brownell . Signed-off-by: Marcin Slusarz Cc: David Brownell Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c index 742be3c35947..054dedd28127 100644 --- a/drivers/usb/misc/usbtest.c +++ b/drivers/usb/misc/usbtest.c @@ -856,6 +856,11 @@ test_ctrl_queue (struct usbtest_dev *dev, struct usbtest_param *param) struct urb *u; struct usb_ctrlrequest req; struct subcase *reqp; + + /* sign of this variable means: + * -: tested code must return this (negative) error code + * +: tested code may return this (negative too) error code + */ int expected = 0; /* requests here are mostly expected to succeed on any