Messages in this thread Patch in this message | | | Date | Sun, 13 Dec 2009 17:57:08 +0100 | From | Eric Dumazet <> | Subject | Re: nfs broken in net-next? -- now in mainline -- bisected: d9f5950f90292f7cc42834338dfd5f44dc4cc4ca |
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Le 13/12/2009 03:41, Yinghai Lu a écrit : > >>> cause the problem: nfs mount fail. >>> >>> the setup is: >>> 64bit kernel, have all needed drivers in kernel, and boot with >>> ip=dhcp, root disk is 256M ramdisk. >>> then try to mount nfs.... >>> >> >> change entries default value from 65536 to 256, >> nfs mount will work. >> > interesting: > > m:~/dump # grep UDP dmesg.txt > [ 28.996034] UDP hash table entries: 65536 (order: 11, 10485760 bytes) > [ 29.032364] UDP-Lite hash table entries: 65536 (order: 11, 10485760 bytes) > > will not work > > but 32768 will work.
Thanks a lot for this work Yinghai ! This last bit helped me a lot ...
Hmm, udp_lib_get_port() assumes it can loop at least one time in :
for (last = first + udptable->mask + 1; first != last; first++) { // unit_work }
but if udptable->mask == 65535, loop is not entered at all (since last == first)
We should convert it to a do { } while(...); construct, or use 32bit variables and (u16) casts.
Thanks
[PATCH] udp: udp_lib_get_port() fix
Now we can have a large udp hash table, udp_lib_get_port() loop should be converted to a do {} while (cond) form, or we dont enter it at all if hash table size is exactly 65536.
Reported-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> --- diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 1f95348..f0126fd 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -216,9 +216,8 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, * force rand to be an odd multiple of UDP_HTABLE_SIZE */ rand = (rand | 1) * (udptable->mask + 1); - for (last = first + udptable->mask + 1; - first != last; - first++) { + last = first + udptable->mask + 1; + do { hslot = udp_hashslot(udptable, net, first); bitmap_zero(bitmap, PORTS_PER_CHAIN); spin_lock_bh(&hslot->lock); @@ -238,7 +237,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, snum += rand; } while (snum != first); spin_unlock_bh(&hslot->lock); - } + } while (++first != last); goto fail; } else { hslot = udp_hashslot(udptable, net, snum); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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