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Fix races between tty.c and sessrele() / doenterpgrp() / leavepgrp(). The tty

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code is still under giant lock, but the session/pgrp release code just used
proctree_locks. This explains why moving the proctree_lock in sys/kern/tty.c
rev. 1.258 did fix the panics in our SMP systems.

This should also fix some race panics with revoked ttys.

Reviewed by:	jhb
MFC after:	1 week
This commit is contained in:
Martin Blapp 2006-09-19 19:25:11 +00:00
parent da7bf2bb26
commit d7b167b57b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=162452
1 changed files with 6 additions and 0 deletions
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6
sys/kern/kern_proc.c
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@ -401,6 +401,7 @@ doenterpgrp(p, pgrp)
fixjobc(p, pgrp, 1);
fixjobc(p, p->p_pgrp, 0);
mtx_lock(&Giant); /* XXX TTY */
PGRP_LOCK(pgrp);
PGRP_LOCK(savepgrp);
PROC_LOCK(p);
@ -410,6 +411,7 @@ doenterpgrp(p, pgrp)
LIST_INSERT_HEAD(&pgrp->pg_members, p, p_pglist);
PGRP_UNLOCK(savepgrp);
PGRP_UNLOCK(pgrp);
mtx_unlock(&Giant); /* XXX TTY */
if (LIST_EMPTY(&savepgrp->pg_members))
pgdelete(savepgrp);
}
@ -425,12 +427,14 @@ leavepgrp(p)
sx_assert(&proctree_lock, SX_XLOCKED);
savepgrp = p->p_pgrp;
mtx_lock(&Giant); /* XXX TTY */
PGRP_LOCK(savepgrp);
PROC_LOCK(p);
LIST_REMOVE(p, p_pglist);
p->p_pgrp = NULL;
PROC_UNLOCK(p);
PGRP_UNLOCK(savepgrp);
mtx_unlock(&Giant); /* XXX TTY */
if (LIST_EMPTY(&savepgrp->pg_members))
pgdelete(savepgrp);
return (0);
@ -455,6 +459,7 @@ pgdelete(pgrp)
*/
funsetownlst(&pgrp->pg_sigiolst);
mtx_lock(&Giant); /* XXX TTY */
PGRP_LOCK(pgrp);
if (pgrp->pg_session->s_ttyp != NULL &&
pgrp->pg_session->s_ttyp->t_pgrp == pgrp)
@ -465,6 +470,7 @@ pgdelete(pgrp)
PGRP_UNLOCK(pgrp);
mtx_destroy(&pgrp->pg_mtx);
FREE(pgrp, M_PGRP);
mtx_unlock(&Giant); /* XXX TTY */
}
static void