svn commit: r218277 - in stable/7/sys: kern sys

[John Baldwin]

On Tuesday, April 19, 2011 8:56:48 am Andre Albsmeier wrote:
> On Mon, 18-Apr-2011 at 15:18:25 +0200, John Baldwin wrote:
> > On Monday, April 18, 2011 7:36:57 am Andre Albsmeier wrote:
> > > On Fri, 15-Apr-2011 at 18:35:05 +0200, John Baldwin wrote:
> > > > On Friday, April 15, 2011 9:25:25 am Andre Albsmeier wrote:
> > > > > On Fri, 04-Feb-2011 at 14:44:59 +0000, John Baldwin wrote:
> > > > > > Author: jhb
> > > > > > Date: Fri Feb  4 14:44:59 2011
> > > > > > New Revision: 218277
> > > > > > URL: http://svn.freebsd.org/changeset/base/218277
> > > > > > 
> > > > > > Log:
> > > > > >   MFC 217075:
> > > > > >   Retire PCONFIG and leave the priority of thread0 alone when waiting for
> > > > > >   interrupt config hooks to execute.
> > > > > >   
> > > > > >   To preserve the KBI, I did not renumber priorities but simply removed
> > > > > >   PCONFIG.
> > > > > > 
> > > > > > Modified:
> > > > > >   stable/7/sys/kern/subr_autoconf.c
> > > > > >   stable/7/sys/sys/priority.h
> > > > > > Directory Properties:
> > > > > >   stable/7/sys/   (props changed)
> > > > > >   stable/7/sys/cddl/contrib/opensolaris/   (props changed)
> > > > > >   stable/7/sys/contrib/dev/acpica/   (props changed)
> > > > > >   stable/7/sys/contrib/pf/   (props changed)
> > > > > > 
> > > > > > Modified: stable/7/sys/kern/subr_autoconf.c
> > > > > > 
> > > > ==============================================================================
> > > > > > --- stable/7/sys/kern/subr_autoconf.c	Fri Feb  4 14:44:42 2011	
> > > > (r218276)
> > > > > > +++ stable/7/sys/kern/subr_autoconf.c	Fri Feb  4 14:44:59 2011	
> > > > (r218277)
> > > > > > @@ -108,7 +108,7 @@ run_interrupt_driven_config_hooks(dummy)
> > > > > >  	warned = 0;
> > > > > >  	while (!TAILQ_EMPTY(&intr_config_hook_list)) {
> > > > > >  		if (msleep(&intr_config_hook_list, &intr_config_hook_lock,
> > > > > > -		    PCONFIG, "conifhk", WARNING_INTERVAL_SECS * hz) ==
> > > > > > +		    0, "conifhk", WARNING_INTERVAL_SECS * hz) ==
> > > > > >  		    EWOULDBLOCK) {
> > > > > >  			mtx_unlock(&intr_config_hook_lock);
> > > > > >  			warned++;
> > > > > 
> > > > > 
> > > > > This broke several of my machines in a somewhat strange way:
> > > > > 
> > > > > After upgrading them (17) to a recent 7-STABLE (as of 2011-04-12)
> > > > > I noticed that some (4) of them didn't start. All 4 didn't find
> > > > > their boot device anymore. What they all got in common is:
> > > > > 
> > > > > - an Adaptec 2940 Ultra SCSI adapter
> > > > > - two SCSI harddisks (da0 and da1) of various brands
> > > > > - one SCSI CDROM drive (cd0)
> > > > > 
> > > > > To be exact, none of the three devices (da0, da1, cd0) were
> > > > > detected at all. Other machines with a similar configuration
> > > > > (2940 and da0/da1) but _without_ the CDROM drive didn't have
> > > > > any problems. So I simply removed the CDROM drives on the 4
> > > > > machines in question and they all booted again.
> > > > > 
> > > > > Today I decided to dig into this and after reverting(*) the
> > > > > above change, they worked with the CDROM again. I have cross-
> > > > > checked it 3 times. No idea what's happening here...
> > > > > 
> > > > > 	-Andre
> > > > > 
> > > > > (*) To be honest, I use this patch so I had to modify only one file:
> > > > > 
> > > > > --- sys/kern/subr_autoconf.c.ORI	2011-02-05 13:14:11.000000000 +0100
> > > > > +++ sys/kern/subr_autoconf.c	2011-04-15 14:34:31.000000000 +0200
> > > > > @@ -108,7 +108,7 @@
> > > > >  	warned = 0;
> > > > >  	while (!TAILQ_EMPTY(&intr_config_hook_list)) {
> > > > >  		if (msleep(&intr_config_hook_list, &intr_config_hook_lock,
> > > > > -		    0, "conifhk", WARNING_INTERVAL_SECS * hz) ==
> > > > > +		    PRI_MIN_KERN + 32, "conifhk", WARNING_INTERVAL_SECS * hz) ==
> > > > >  		    EWOULDBLOCK) {
> > > > >  			mtx_unlock(&intr_config_hook_lock);
> > > > >  			warned++;
> > > > 
> > > > Do you get any warnings about CAM timeouts, etc. when these probe?  A verbose 
> > > > dmesg might be nice to look at if possible.
> > > 
> > > OK, I have set up a machine for testing. In my other mail
> > > I was wrong saying that the pass devices appear when using
> > > the problematic kernel...
> > > 
> > > Here are the dmesgs:
> > > 
> > > - dmesg_bad is the original kernel as of Friday
> > > - dmesg_ok is the patched kernel (see above) as of Friday
> > > - dmesg.diff is the diff between both
> > > 
> > > If you want me to try something just tell me...
> > 
> > Hmmm, what if you make SCSI_DELAY larger?  Also, can you let it fail the
> > mount and drop into ddb and then get 'ps' output?
> 
> As soon as I include the debugger into the kernel the problem
> is gone. I have double-checked it two times now: With debugger
> the drives are detected, without debugger mostly (but not always)
> not.
> 
> I currently have it running in an endless rebooting loop hoping,
> that it fails eventually...

Hummm.  This seems like it is a timing related race. :(

-- 
John Baldwin