Re: kern/38273 panic: LOCKDEBUG, "lockdebug_barrier: spin lock held", from ld_ataraid_start_raid0()

["Greg A. Woods" <woods%planix.com@localhost>]

The following reply was made to PR kern/38273; it has been noted by GNATS.

From: "Greg A. Woods" <woods%planix.com@localhost>
To: NetBSD GNATS <gnats-bugs%NetBSD.org@localhost>
Cc: Juan RP <xtraeme%gmail.com@localhost>
Subject: Re: kern/38273 panic: LOCKDEBUG, "lockdebug_barrier: spin lock held", 
from ld_ataraid_start_raid0()
Date: Fri, 19 Sep 2008 16:20:17 -0400

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 At Thu, 18 Sep 2008 20:10:05 +0000 (UTC), Juan RP wrote:
 Subject: Re: kern/38273 panic: LOCKDEBUG, "lockdebug_barrier: spin lock hel=
 d", from ld_ataraid_start_raid0()
 >=20
 >  I'm out of ideas then. No idea how we will fix this if we are calling
 >  buf_init() with the ld's spin lock held!
 > =20
 >  Or ldstart() is wrong and it should not acquire the spin lock there
 >  (AFAIK is the correct way) or the only option is to release/reacquire
 >  the spin lock as I had done in the patch.
 > =20
 >  Also as the spin lock is held, acquiring the adaptive mutex from v_inter=
 lock
 >  will also cause another "spin lock held" panic later on (which I address=
 ed
 >  with the softint(9)).
 
 Perhaps we should post some further details about these issues on
 tech-kern.
 
 I'm certainly not knowledgeable enough about the twisty new maze of
 locking necessary for disk drivers, especially not middle-layer drivers
 like this one, to be of much help sorting this out.  (I would like to
 learn, but I'd like to do it from a detailed design document but I don't
 think one currently exists.)
 
 Perhaps someone else cognizant of all the issues could lend a hand.
 
 --=20
                                                Greg A. Woods
                                                Planix, Inc.
 
 <woods%planix.com@localhost>     +1 416 489-5852 x122     
http://www.planix.com/
 
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