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Update some stale comments regarding tcbinfo locking in the TCP input

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path: read locks on tcbinfo are no longer used, so won't happen.  No
functional change.

MFC after:	3 days
This commit is contained in:
Robert Watson 2012-07-22 17:31:36 +00:00
parent f7a3729c91
commit 0989f56cff
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=238699
1 changed files with 3 additions and 10 deletions
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13
sys/netinet/tcp_input.c
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@ -909,7 +909,7 @@ tcp_input(struct mbuf *m, int off0)
/*
* A previous connection in TIMEWAIT state is supposed to catch stray
* or duplicate segments arriving late. If this segment was a
* legitimate new connection attempt the old INPCB gets removed and
* legitimate new connection attempt, the old INPCB gets removed and
* we can try again to find a listening socket.
*
* At this point, due to earlier optimism, we may hold only an inpcb
@ -1438,15 +1438,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
/*
* If this is either a state-changing packet or current state isn't
* established, we require a write lock on tcbinfo. Otherwise, we
* allow either a read lock or a write lock, as we may have acquired
* a write lock due to a race.
*
* Require a global write lock for SYN/FIN/RST segments or
* non-established connections; otherwise accept either a read or
* write lock, as we may have conservatively acquired a write lock in
* certain cases in tcp_input() (is this still true?). Currently we
* will never enter with no lock, so we try to drop it quickly in the
* common pure ack/pure data cases.
* allow the tcbinfo to be in either alocked or unlocked, as the
* caller may have unnecessarily acquired a write lock due to a race.
*/
if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
tp->t_state != TCPS_ESTABLISHED) {