Date: Fri, 01 Oct 2004 01:55:30 -0400 From: Stephan Uphoff <ups@tree.com> To: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Cc: Julian Elischer <julian@elischer.org> Subject: sched_switch (sched_4bsd) may be preempted Message-ID: <1096610130.21577.219.camel@palm.tree.com>
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sched_switch (sched_4bsd) may be preempted in setrunqueue or slot_fill.
This could be ugly.
Wrapping it into a critical section and resetting TDP_OWEPREEMPT should
work.
Hand trimmed patch:
RCS file: /cvsroot/src/sys/kern/sched_4bsd.c,v
retrieving revision 1.65
diff -u -r1.65 sched_4bsd.c
--- sys/kern/sched_4bsd.c 16 Sep 2004 07:12:59 -0000 1.65
+++ sys/kern/sched_4bsd.c 1 Oct 2004 05:35:28 -0000
@@ -823,6 +823,7 @@
TD_SET_CAN_RUN(td);
else {
td->td_ksegrp->kg_avail_opennings++;
+ critical_enter();
if (TD_IS_RUNNING(td)) {
/* Put us back on the run queue (kse and all).
*/
setrunqueue(td, SRQ_OURSELF|SRQ_YIELDING);
@@ -834,6 +835,8 @@
*/
slot_fill(td->td_ksegrp);
}
+ critical_exit();
+ td->td_pflags &= ~TDP_OWEPREEMPT;
}
if (newtd == NULL)
newtd = choosethread();
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