On Fri, 8 Oct 2004, Kris Kennaway wrote: > pointyhat (SMP machine running RELENG_5) has twice in the past 2 days > gone into an infinite loop in the tcp_output() function (repeatedly > breaking into DDB and continuing, I can see it at different points in > the code). I made tcp_output keep a counter and increment when it hits > the again: label. If the counter reaches 1000, it panics. This > happened again just now: There is a small but non-zero chance that the commit I just made to tcp_output.c to add some missing locking around socket buffer accesses might affect (fix?) this problem. The change was tcp_output.c:1.103, if you want to give it a spin. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert_at_fledge.watson.org Principal Research Scientist, McAfee Research > panic: Looping in tcp_output > cpuid = 0 > KDB: enter: panic > [thread 100043] > Stopped at kdb_enter+0x30: leave > db> tr > kdb_enter(c06de69a,0,c06e973a,ebbd5ba0,c34cd4b0) at kdb_enter+0x30 > panic(c06e973a,0,ebbd5b68,0,0) at panic+0x14e > tcp_output(c395f8c0,c395f8c0,c3ed3e10,c05a79f0,ebbd5ca0) at tcp_output+0x19e > tcp_drop(c395f8c0,3c,c06e9fe7,1ab,e) at tcp_drop+0x30 > tcp_timer_persist(c395f8c0,0,c06df6ba,f5,0) at tcp_timer_persist+0x14c > softclock(0,0,c06dc037,269,c0738ac0) at softclock+0x1c8 > ithread_loop(c345d800,ebbd5d48,c06dbe2a,323,41531744) at ithread_loop+0x172 > fork_exit(c04f1210,c345d800,ebbd5d48) at fork_exit+0xc6 > fork_trampoline() at fork_trampoline+0x8 > --- trap 0x1, eip = 0, esp = 0xebbd5d7c, ebp = 0 --- > > This might be related to SACK, which is one of the situations where we > loop back to the again label, but that's just a guess.Received on Sat Oct 09 2004 - 15:51:56 UTC
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