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authorMarcin Slusarz <marcin.slusarz@gmail.com>2008-05-12 20:17:25 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2008-05-14 10:00:29 -0700
commit6def755320a214ae149ad6bc69eb8c1d7887e678 (patch)
tree11b454791e631d3e8f38b0ee6c811ab2bed2d7c8 /drivers/usb/misc/usbtest.c
parent5fc89390f74ac42165db477793fb30f6a200e79c (diff)
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 <david-b@pacbell.net>. Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/misc/usbtest.c')
-rw-r--r--drivers/usb/misc/usbtest.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index 742be3c3594..054dedd2812 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