Bogus usage of tsleep(9) in USB.

[M. Warner Losh]

In message: <20040820090006.GX30151 at darkness.comp.waw.pl>
            Pawel Jakub Dawidek <pjd at freebsd.org> writes:
: There are many calls to tsleep(9) with no timeout in our USB code.
: As you all know, it is not permitted and we have KASSERT() for this:
: 
:         KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL,
:             ("sleeping without a mutex"));
: 
: ehci.c:2441:    tsleep(&sc->sc_softwake, PZERO, "ehciab", 0);
: ohci.c:2288:    tsleep(&sc->sc_softwake, PZERO, "ohciab", 0);
: ubser.c:882:            tsleep(&sc->sc_opening, PRIBIO, "ubser_op", 0);
: ucom.c:275:             tsleep(&sc->sc_opening, PRIBIO, "ucomop", 0);
: ugen.c:633:                     error = tsleep(sce, PZERO | PCATCH, "ugenri", 0);
: ugen.c:697:                     error = tsleep(sce, PZERO | PCATCH, "ugenri", 0);
: uhci.c:1982:    tsleep(&sc->sc_softwake, PZERO, "uhciab", 0);
: uhid.c:496:             error = tsleep(&sc->sc_q, PZERO | PCATCH, "uhidrea", 0);
: ums.c:639:              error = tsleep(sc, PZERO | PCATCH, "umsrea", 0);
: usb.c:456:                      tsleep(&usb_all_tasks, PWAIT, "usbtsk", 0);
: usb.c:534:              error = tsleep(&usb_events, PZERO | PCATCH, "usbrea", 0);
: usbdi.c:342:            tsleep(xfer, PRIBIO, "usbsyn", 0);
: usbdi_util.c:435:       error = tsleep(xfer, PZERO | PCATCH, lbl, 0);
: usbdi_util.c:477:       error = tsleep(xfer, PZERO | PCATCH, lbl, 0);
: 
: I saw only panic on tsleep(9) from usbdi.c, so I know for sure we don't
: hold Giant there.

Most of the usb stack will be called with GIANT held, which is likely
why you haven't seen more panics.  I'd suspect that the panic you are
seeing from usbdi() due to other bogosity.

Warner