kern/51352: panic: malloc(M_WAITOK) in interrupt context

[Mark Gooderum]

The following reply was made to PR kern/51352; it has been noted by GNATS.

From: Mark Gooderum <mark at verniernetworks.com>
To: Mark Gooderum <mark at verniernetworks.com>
Cc: freebsd-gnats-submit at FreeBSD.org, dada at sbox.tugraz.at,
	Archie Cobbs <archie at packetdesign.com>
Subject: Re: kern/51352: panic: malloc(M_WAITOK) in interrupt context
Date: Mon, 19 May 2003 14:00:05 -0700

 Sorry - probably a false alarm on my part - confusing splnet() with 
 intr_nesting_level.
 --
 Mark
 
 > I've managed to trigger this running a kernel with DIAGNOSTIC and 
 > INVARIANTS - the core is always the traceback below.  This is running 
 > 4.7.
 >
 > The offending MALLOC() is in dup_sockaddr() - which takes a flag for 
 > "canblock".  The dup_sockaddr() call is from sorecieve() which 
 > _always_ calls dup_sockaddr() at splnet() with the canwait flag 
 > usually set to true (always in this particular code path down from 
 > recvfrom() as far as I can tell). Something here is a bug - if the 
 > MALLOC() blocks the socket code can get back to where it is so the 
 > splnet() to protect that socket is in fact not protecting the socket 
 > so I can see bad JuJu happening but I haven't discerned the full 
 > nature of this juju.
 >
 > But I don't understand enough of the socket code yet to say whether I 
 > can safely say don't wait always (as it looks like the code doesn't 
 > particulary seem to check or care if the dup fails).
 >