Messages in this thread | | | Date | Fri, 12 Nov 2010 21:29:59 +0300 | From | Alexey Kuznetsov <> | Subject | Re: a problem tcp_v4_err() |
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Hello!
On Fri, Nov 12, 2010 at 07:12:58PM +0100, Eric Dumazet wrote: > I see socket is locked around line 368, > > bh_lock_sock(sk); > /* If too many ICMPs get dropped on busy > * servers this needs to be solved differently. > */ > if (sock_owned_by_user(sk)) > NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); > > > Hmm, maybe some goto is missing ;)
It is not missing, sock_owned_by_user() is checked later when some operation which cannot be done without lock is required. It was done to save error in sk_err_soft even when socket is locked.
This code also _understands_ this: look at
} else if (sock_owned_by_user(sk)) { /* RTO revert clocked out retransmission, * but socket is locked. Will defer. */ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, HZ/20, TCP_RTO_MAX);
but somehow it considers the manipulations with rto/backoff/write_queue as safe. Seems, they are not.
Alexey
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