Re: tun(4) in -CURRENT: No buffer space available - race condition patch

Dnia 15.09.2010 John Baldwin <jhb_at_freebsd.org> napisał/a:
> On Monday, September 13, 2010 9:10:01 pm Marcin Cieslak wrote:
>> Output queue of tun(4) gets full after some time when sending lots of data.
>> I have been observing this on -CURRENT at least since March this year.
>> 
>> Looks like it's a race condition (same in tun(4) and tap(4)), 
>> the following patch seems to address the issue:
>
> This is a good find.  I actually went through these drivers a bit further and 
> have a bit of a larger patch to extend the locking some.  Would you care to 
> test it?

Sure, I am installing it right now (for if_tun right now).

There are also a LORs during tunclose (I always get one of them when closing the
tunnel):

-------8<--------------------------------------------------------------------------
lock order reversal:
 1st 0xc24db8c8 rtentry (rtentry) _at_ /usr/src/sys/net/route.c:370
 2nd 0xc2472a04 if_afdata (if_afdata) _at_ /usr/src/sys/netinet6/scope6.c:417
KDB: stack backtrace:
db_trace_self_wrapper(c0a4b284,cce14714,c0723185,c0715b2b,c0a4d1f8,...) at db_trace_self_wrapper+0x26
kdb_backtrace(c0715b2b,c0a4d1f8,c0c4f308,c21186e8,cce1476c,...) at kdb_backtrace+0x29
_witness_debugger(c0a4d1f8,c2472a04,c0a539ec,c211dfe0,c0a63771,...) at _witness_debugger+0x25
witness_checkorder(c2472a04,9,c0a63771,1a1,0,...) at witness_checkorder+0x6aa
_rw_wlock(c2472a04,c0a63771,1a1,0,c2472a04,...) at _rw_wlock+0x38
in6_setscope(cce148c4,c2472800,0,cce147fc,cce147e0,...) at in6_setscope+0x30
in6_purgeaddr(c2539600,0,0,c211e048,c2362364,...) at in6_purgeaddr+0x4af
if_purgeaddrs(c2472800,2,0,1cd,c24ab4c0,...) at if_purgeaddrs+0xb0
tunclose(c24d1000,3,2000,c23622c0,1,...) at tunclose+0x197
giant_close(c24d1000,3,2000,c23622c0,c23622c0,...) at giant_close+0x6e
devfs_close(cce14a78,cce14a9c,c07785fb,c0aae500,cce14a78,...) at devfs_close+0x2a9
VOP_CLOSE_APV(c0aae500,cce14a78,c0a532d0,12d,c0af0160,...) at VOP_CLOSE_APV+0x42
vn_close(c24ccaa0,3,c2160c80,c23622c0,c23622c0,...) at vn_close+0xdb
vn_closefile(c24bc0e0,c23622c0,c24bc0e0,0,cce14b28,...) at vn_closefile+0xe4
devfs_close_f(c24bc0e0,c23622c0,3,0,c24bc0e0,...) at devfs_close_f+0x2b
_fdrop(c24bc0e0,c23622c0,cce14b5c,c072327c,0,...) at _fdrop+0x43
closef(c24bc0e0,c23622c0,721,71e,c2362364,...) at closef+0x277
fdfree(c23622c0,0,c0a4549c,107,80000000,...) at fdfree+0x3ba
exit1(c23622c0,0,cce14c7c,c071da4a,c23622c0,...) at exit1+0x465
sys_exit(c23622c0,cce14cec,stray irq7
c06a7bac,1,0,...) at sys_exit+0x1d
syscallenter(c23622c0,cce14ce4,c06d6stray irq7
d5d,c0cae934,8,...) at syscallenter+0x25a
syscall(cce14d28) at syscall+0x34
Xint0x80_syscall() at Xint0x80_syscall+0x21
--- syscall (1, FreeBSD ELF32, sys_exit), eipstray irq7
 = 0x28128acf, esp = 0xbfbfed80, ebp = 0xbfbfed8c ---
^Ctun0: link state changed to DOWN
-------8<--------------------------------------------------------------------------
lock order reversal:
 1st 0xc24db8c8 rtentrystray irq7
 (rtentry) _at_ /usr/src/sys/net/route.c:370
 2nd 0xc2482604 if_afdata (if_afdata) _at_ /usr/src/sys/netinet6/scope6.c:417
KDB: stack backtrace:
db_trace_self_wrapper(c0a4912e,cce16714,c0723105,c0715aab,c0a4b0a2,...) at db_trace_self_wrapper+0x26
kdb_backtrace(c0715aab,c0a4b0a2,c0c4cb58,c21176e8,cce1676c,...) at kdb_backtrace+0x29
_witness_debugger(c0a4b0a2,c2482604,c0a51896,c211cfe0,c0a6137e,...) at _witness_debugger+0x25
witness_checkorder(c2482604,9,c0a6137e,1a1,0,...) at witness_checkorder+0x6aa
_rw_wlock(c2482604,c0a613stray irq7
7e,1a1,c0793997,c2482604,...) at _rw_wlock+0x38
in6_setscope(cce168c4,c2482400,0,cce167fc,cce167e0,...) at in6_setscope+0x30
in6_purgeaddr(c253e000,0,0,c211d048,c2361364,...) at in6_purgeaddr+0x4af
if_purgeaddrs(c2482400,2,0,1cd,c24aa5c0,...) at if_purgeaddrs+0xb0
tunclose(c2539a00,3,2000,c23612c0,1,...) at tunclose+0x136
giant_close(c2539a00,3,2000,c23612c0,c23612c0,...) at giant_close+0x6e
devfs_close(cce16a78,cce16a9c,c077857b,c0aac0e0,cce16a78,...) at devfs_close+0x2a9
VOP_CLOSE_APV(c0aac0e0,cce16a78,c0a5117a,12d,c0aedac0,...) at VOP_CLOSE_APV+0x42
vn_close(c25d2770,3,c215fc80,c23612c0,c0b10180,...) at vn_close+0xdb
vn_closefile(c24bba10,c23612c0,c24bba10,0,cce16b28,...) at vn_closefile+0xe4
devfs_close_f(c24bba10,c23612c0,3,0,c24bba10,...) at devfs_close_f+0x2b
_fdrop(c24bba10,c23612c0,cce16b5c,c07231fc,0,...) at _fdrop+0x43
closef(c24bba10,c23612c0,721,71e,c2361364,...) at closef+0x277
fdfree(c23612c0,0,c0a43346,107,c2361364,...) at fdfree+0x3ba
exit1(c23612c0,0,cce16c7c,c071d9ca,c23612c0,...) at exit1+0x465
sys_exit(c23612c0,cce16cec,28087460,1,0,...) at sys_exit+0x1d
syscallenter(c23612c0,cce16ce4,c09a564e,c23612c0,cce16d28,...) at syscallenter+0x25a
syscall(cce16d28) at syscall+0x34
Xint0x80_syscall() at Xint0x80_syscall+0x21
--- syscall (1, FreeBSD ELF32, sys_exit), eip = 0x28128acf, esp = 0xbfbfed80, ebp = 0xbfbfed8c ---
tun0: link state changed to DOWN
-------8<--------------------------------------------------------------------------

--Marcin