USB microphones with FreeBSD-CURRENT: bug 194727, r358629

[Theron]

On 2020-03-30 20:08, Graham Perrin wrote:
> Theron, thank you! That might explain a recent sense of randomness 
> with the symptoms. I've been testing in three different boot 
> environments, only one of which is above the 358629 at 
> <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194727#c22>:

I don't know what would be attaching to mixer before login.  For me the 
problem is predictable: suspending after I've opened a player reliably 
hangs kernel, and killing every user of /dev/dsp* /dev/mixer* before 
sleep reliably avoids the problem.  Maybe something is attaching on startup.

> (In retrospect, most remarkable to me was that the bug could bite 
> before logging in; taking the 'Sleep' option in sddm did not lead to a 
> suspend of the system. Hopefully fixed for FreeBSD-CURRENT by r358629; 
> I'll not test now, maybe later in the week.)

As I understand it, r358629 adds a mechanism that applications can use 
to "do the right thing" but does not fix the underlying kernel 
vulnerability.

Theron