[TEST] device and fifo vnode bypass, Giantfree select/poll

This solves the problem seen in the device vnode bypass mode
(vfs.devfs.fops=1), typically with a message like:

	panic: specread() on un-referenced struct cdev *(ttyp1)

Please try setting vfs.devfs.fops=1 in loader.conf again and beat
up the code even harder.

I have code in p4:phk_bufwork which does vnode bypass for FIFOs
and Giant free select(2)/poll(2) for networking.  If you have
perforce access, please help beat up on this code.

Poul-Henning


In message <200411132321.iADNLsZN032634_at_repoman.freebsd.org>, Poul-Henning Kamp
 writes:
>phk         2004-11-13 23:21:54 UTC
>
>  FreeBSD src repository
>
>  Modified files:
>    sys/fs/devfs         devfs_vnops.c 
>  Log:
>  Add the devfs_fp_check() function which helps us get from a struct file
>  to a cdev and a devsw, doing all the relevant checks along the way.
>  
>  Add the check to see if fp->f_vnode->v_rdev differs from our cached
>  fp->f_data copy of our cdev.  If it does the device was revoked and
>  we return ENXIO.
>  
>  Revision  Changes    Path
>  1.83      +34 -70    src/sys/fs/devfs/devfs_vnops.c
>

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.