Patch for nvidia-driver on current (panic: spin locks can only
use msleep_spin)
John Baldwin
jhb at freebsd.org
Wed Oct 10 14:31:28 PDT 2007
On Tuesday 02 October 2007 04:48:57 pm Craig Boston wrote:
> Hi all, I did some more investigating and found what was causing the
> nvidia driver to occasionally panic on my machine. It calls cv_wait(9)
> using a spin mutex, which according to the man page is a no-no.
>
> I simply changed the os_*_sema interfaces to use a standard mutex
> instead. Tried running a bunch of glxgears and xscreensaver GL demos in
> parallel and haven't been able to reproduce a panic since. As a bonus,
> the 5 second pause I would sometimes get when a GL-based xscreensaver
> process terminates seems to be gone as well.
>
> There doesn't appear to be any documentation that I could find as to
> what contexts those functions may be called from. I'm not a locking
> guru, so I can't say for certain why a spin mutex was being used. Wild
> guess: an artifact from the 4.x or 5.x code that may be obsoleted by
> adaptive mutexes.
>
> Patch is attached; cc danfe@ in case others report this problem to him.
Your patch is good, and I think nvidia is going to fix their driver to use a
regular mutex as well. It probably uses a spin mutex because on other OS's
you have to use a spin mutex to protect data shared with an interrupt
handler. However, in the case of FreeBSD, you only use a spin mutex if you
use an INTR_FAST/filter handler, and can use a regular mutex otherwise.
--
John Baldwin
More information about the freebsd-current
mailing list