Author: mdf
Date: Wed Sep 1 20:32:47 2010
New Revision: 212115
URL: http://svn.freebsd.org/changeset/base/212115
Log:
Fix a bug with sched_affinity() where it checks td_pinned of another
thread in a racy manner, which can lead to attempting to migrate a
thread that is pinned to a CPU. Instead, have sched_switch() determine
which CPU a thread should run on if the current one is not allowed.
KASSERT in sched_bind() that the thread is not yet pinned to a CPU.
KASSERT in sched_switch() that only migratable threads or those moving
due to a sched_bind() are changing CPUs.
sched_affinity code came from j...@.
MFC after: 2 weeks
Modified:
head/sys/kern/sched_ule.c
Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c Wed Sep 1 20:25:36 2010 (r212114)
+++ head/sys/kern/sched_ule.c Wed Sep 1 20:32:47 2010 (r212115)
@@ -1797,10 +1797,16 @@ sched_switch(struct thread *td, struct t
srqflag = (flags & SW_PREEMPT) ?
SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
SRQ_OURSELF|SRQ_YIELDING;
+ if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
+ ts->ts_cpu = sched_pickcpu(td, 0);
if (ts->ts_cpu == cpuid)
tdq_runq_add(tdq, td, srqflag);
- else
+ else {
+ KASSERT(THREAD_CAN_MIGRATE(td) ||
+ (ts->ts_flags & TSF_BOUND) != 0,
+ ("Thread %p shouldn't migrate", td));
mtx = sched_switch_migrate(tdq, td, srqflag);
+ }
} else {
/* This thread must be going to sleep. */
TDQ_LOCK(tdq);
@@ -2383,7 +2389,6 @@ sched_affinity(struct thread *td)
{
#ifdef SMP
struct td_sched *ts;
- int cpu;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
@@ -2397,17 +2402,13 @@ sched_affinity(struct thread *td)
if (!TD_IS_RUNNING(td))
return;
td->td_flags |= TDF_NEEDRESCHED;
- if (!THREAD_CAN_MIGRATE(td))
- return;
/*
- * Assign the new cpu and force a switch before returning to
- * userspace. If the target thread is not running locally send
- * an ipi to force the issue.
+ * Force a switch before returning to userspace. If the
+ * target thread is not running locally send an ipi to force
+ * the issue.
*/
- cpu = ts->ts_cpu;
- ts->ts_cpu = sched_pickcpu(td, 0);
- if (cpu != PCPU_GET(cpuid))
- ipi_cpu(cpu, IPI_PREEMPT);
+ if (td != curthread)
+ ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
#endif
}
@@ -2424,6 +2425,7 @@ sched_bind(struct thread *td, int cpu)
ts = td->td_sched;
if (ts->ts_flags & TSF_BOUND)
sched_unbind(td);
+ KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
ts->ts_flags |= TSF_BOUND;
sched_pin();
if (PCPU_GET(cpuid) == cpu)
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