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Add a new global mutex, so_global_mtx, which protects the global variables

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so_gencnt, numopensockets, and the per-socket field so_gencnt.  Annotate
this this might be better done with atomic operations.

Annotate what accept_mtx protects.
This commit is contained in:
Robert Watson 2004-06-27 03:22:15 +00:00
parent 6efb916277
commit a290574663
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=131167
1 changed files with 26 additions and 2 deletions
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28
sys/kern/uipc_socket.c
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@ -106,9 +106,22 @@ SYSCTL_INT(_kern_ipc_zero_copy, OID_AUTO, send, CTLFLAG_RW,
&so_zero_copy_send, 0, "Enable zero copy send");
#endif /* ZERO_COPY_SOCKETS */
/*
* accept_mtx locks down per-socket fields relating to accept queues. See
* socketvar.h for an annotation of the protected fields of struct socket.
*/
struct mtx accept_mtx;
MTX_SYSINIT(accept_mtx, &accept_mtx, "accept", MTX_DEF);
/*
* so_global_mtx protects so_gencnt, numopensockets, and the per-socket
* so_gencnt field.
*
* XXXRW: These variables might be better manipulated using atomic operations
* for improved efficiency.
*/
static struct mtx so_global_mtx;
MTX_SYSINIT(so_global_mtx, &so_global_mtx, "so_glabel", MTX_DEF);
/*
* Socket operation routines.
@ -146,11 +159,12 @@ soalloc(int mflags)
#endif
SOCKBUF_LOCK_INIT(&so->so_snd, "so_snd");
SOCKBUF_LOCK_INIT(&so->so_rcv, "so_rcv");
/* XXX race condition for reentrant kernel */
so->so_gencnt = ++so_gencnt;
/* sx_init(&so->so_sxlock, "socket sxlock"); */
TAILQ_INIT(&so->so_aiojobq);
mtx_lock(&so_global_mtx);
so->so_gencnt = ++so_gencnt;
++numopensockets;
mtx_unlock(&so_global_mtx);
}
return so;
}
@ -230,7 +244,9 @@ sodealloc(struct socket *so)
{
KASSERT(so->so_count == 0, ("sodealloc(): so_count %d", so->so_count));
mtx_lock(&so_global_mtx);
so->so_gencnt = ++so_gencnt;
mtx_unlock(&so_global_mtx);
if (so->so_rcv.sb_hiwat)
(void)chgsbsize(so->so_cred->cr_uidinfo,
&so->so_rcv.sb_hiwat, 0, RLIM_INFINITY);
@ -250,7 +266,15 @@ sodealloc(struct socket *so)
SOCKBUF_LOCK_DESTROY(&so->so_rcv);
/* sx_destroy(&so->so_sxlock); */
uma_zfree(socket_zone, so);
/*
* XXXRW: Seems like a shame to grab the mutex again down here, but
* we don't want to decrement the socket count until after we free
* the socket, and we can't increment the gencnt on the socket after
* we free, it so...
*/
mtx_lock(&so_global_mtx);
--numopensockets;
mtx_unlock(&so_global_mtx);
}
int