From 1dada07c09ab31e456a902cd2f6f80db7943fdb2 Mon Sep 17 00:00:00 2001 From: mdf Date: Wed, 15 Sep 2010 15:53:05 +0000 Subject: [PATCH] MFC r212115: 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. Note that this is direct commit as ipi_cpu() only exists in CURRENT. git-svn-id: svn://svn.freebsd.org/base/stable/8@212666 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- sys/kern/sched_ule.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c index a4f5b2ca9..0d67946c3 100644 --- a/sys/kern/sched_ule.c +++ b/sys/kern/sched_ule.c @@ -1803,10 +1803,16 @@ sched_switch(struct thread *td, struct thread *newtd, int flags) 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); @@ -2389,7 +2395,6 @@ sched_affinity(struct thread *td) { #ifdef SMP struct td_sched *ts; - int cpu; THREAD_LOCK_ASSERT(td, MA_OWNED); ts = td->td_sched; @@ -2403,17 +2408,13 @@ 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_selected(1 << cpu, IPI_PREEMPT); + if (td != curthread) + ipi_selected(1 << ts->ts_cpu, IPI_PREEMPT); #endif } @@ -2430,6 +2431,7 @@ 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) -- 2.45.0