RE: Sleeping on "isp_mboxwaiting" with the following non-sleepablelocks held:

Well, I don't agree with the design here, but it is what it is. I'll
make the change that you've added a requirement for. 

-----Original Message-----
From: Poul-Henning Kamp [mailto:phk_at_phk.freebsd.dk] 
Sent: Tuesday, October 21, 2003 2:46 PM
To: mjacob_at_feral.com
Cc: 'Kris Kennaway'; alpha_at_freebsd.org; current_at_freebsd.org
Subject: Re: Sleeping on "isp_mboxwaiting" with the following
non-sleepablelocks held: 


In message <000801c3981a$8abc6540$23a610ac_at_win2k>, "Matthew Jacob"
writes:
>So? How about some details and context?
>
>I thought was told that being able to use locks in HBAs is fine. I had 
>them on for a while, and then had them off. I turned them on again over

>a month ago. I'm somewhat surprised to see that a problem shows up now.
>
>*I* do the right thing with locks, IMO. I hold them in my module when I

>enter and release them if/when I leave. Seeing a lock held by some 
>random caller causing me to blow up to me seems to be a hole in the 
>architecture, but I'd be the first to admit that I hardly am up to date

>on what the rules of the road are now so such an opinion is 
>ill-informed.

The lock held in this case, is not "some random caller", that is a mutex
held specifically to expose device drivers which try to sleep in their
->strategy() function.

You cannot sleep in the strategy() function because that would hold op
I/O, and therefore likely lead to deadlock.

-- 
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.