assertion "solocked(sb->sb_so)" failed [Re: diagnostic assertion "solocked2(so, so2)" failed]

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Aug 12, 2009 at 04:53:19PM +0200, Manuel Bouyer wrote:
> On Tue, Aug 11, 2009 at 11:09:32AM +0200, Manuel Bouyer wrote:
> > Hi,
> > I got this panic on a netbsd-5 kernel:
> > panic: kernel diagnostic assertion "solocked2(so, so2)" failed: file 
> > "/home/bouyer/src-5/src/sys/kern/uipc_usrreq.c", line 559                   
> >                
> 
> ad@ pointed me to kern/38968 which is the same problem. From his
> analysis it's a broken assertion. I could just remove the KASSERT
> but I suspect other assertions using solocked2() are also broken; this needs
> to be analysed. For now I'm just going to change solocked2() to always return
> true, as suggected by ad.

After doing so I got this panic:

panic: kernel diagnostic assertion "solocked(sb->sb_so)" failed: file 
"/home/bouyer/src-5/src/sys/kern/uipc_socket2.c", line 726                      
          
fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c03d033c cs 8 eflags 246 cr2 8077132 ilevel 4
Stopped in pid 16273.1 (sendmail) at    netbsd:breakpoint+0x4:  popl    %ebp
db{1}> 
breakpoint(c0634177,d5ad8b18,c2cca800,c02ffb02,cbf35d82,c32b003c,ffffffff,d5ad8c10,d5ad8c74,d5ad8c94)
 at netbsd:breakpoint+0x4
panic(c0673c0c,c05f9751,c05fb357,c062a5f0,2d6,1,d5ad8b4c,c035ede2,c05f9751,c062a5f0)
 at netbsd:panic+0x1b0
__kernassert(c05f9751,c062a5f0,2d6,c05fb357,c31bfba4,c2f94300,d5ad8b7c,c03645e1,c31bfc5c,c2e6a200)
 at netbsd:__kernassert+0x39
sbappend(c31bfc5c,c2e6a200,c2e6a23d,c,d1d186ac,d23d696c,c2e6a249,d1ded2c0,0,0) 
at netbsd:sbappend+0x92
uipc_usrreq(c31b6a54,9,c2e6a200,0,0,d18ad300,3,ad8be0,c31b6aac,0) at 
netbsd:uipc_usrreq+0x741
sosend(c31b6a54,0,d5ad8c94,c2e6a200,0,0,d18ad300,9,0,2) at netbsd:sosend+0x403
soo_write(d5bd6300,d5bd6300,d5ad8c94,d5a81000,1,d5ad8bdc,d5bd6300,d5ad8c54,0,10)
 at netbsd:soo_write+0x3e
do_filewritev(5,bfbfc370,2,d5bd6300,1,d5ad8d28,d5ad8d3c,c03d88e8,d18ad300,d5ad8d00)
 at netbsd:do_filewritev+0x190
sys_writev(d18ad300,d5ad8d00,d5ad8d28,8077000,d1d186ac,d1d186ac,1,5,bfbfc370,2) 
at netbsd:sys_writev+0x37
syscall(d5ad8d48,b3,ab,2b,2b,1,bfbfc3d8,bfbfc398,bb92a0b0,0) at 
netbsd:syscall+0xc8

this sbappend() is called a few lines after the KASSERT(solocked2(so, so2))
that was triggered before. m is not NULL. At this point this KASSERT
doens't look bogus, it doesn't look safe to get there without a lock held.
Any idea, someone ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--