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| author | Jeff Roberson <jeff@FreeBSD.org> | 2020-01-23 03:36:50 +0000 |
|---|---|---|
| committer | Jeff Roberson <jeff@FreeBSD.org> | 2020-01-23 03:36:50 +0000 |
| commit | 1eb13fce849fe14260a24656d532fd7700d92d6b (patch) | |
| tree | 6d37bab4e711640eab98d04f9a7dccad30d05199 /sys/kern/sched_ule.c | |
| parent | e87ad0ab37f5cb7d7bd40b5f8c8b43a83f516737 (diff) | |
| download | src-1eb13fce849fe14260a24656d532fd7700d92d6b.tar.gz src-1eb13fce849fe14260a24656d532fd7700d92d6b.zip | |
Block the thread lock in sched_throw() and use cpu_switch() to unblock
it. The introduction of lockless switch in r355784 created a race to
re-use the exiting thread that was only possible to hit on a hypervisor.
Reported/Tested by: rlibby
Discussed with: rlibby, jhb
Notes
Notes:
svn path=/head/; revision=357014
Diffstat (limited to 'sys/kern/sched_ule.c')
| -rw-r--r-- | sys/kern/sched_ule.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c index 3c35179e2bee..7dc48a2336bf 100644 --- a/sys/kern/sched_ule.c +++ b/sys/kern/sched_ule.c @@ -2894,7 +2894,7 @@ sched_throw(struct thread *td) struct thread *newtd; struct tdq *tdq; - if (td == NULL) { + if (__predict_false(td == NULL)) { #ifdef SMP PCPU_SET(sched, DPCPU_PTR(tdq)); #endif @@ -2912,13 +2912,18 @@ sched_throw(struct thread *td) tdq_load_rem(tdq, td); td->td_lastcpu = td->td_oncpu; td->td_oncpu = NOCPU; + thread_lock_block(td); } newtd = choosethread(); spinlock_enter(); TDQ_UNLOCK(tdq); KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count %d", curthread->td_md.md_spinlock_count)); - cpu_throw(td, newtd); /* doesn't return */ + /* doesn't return */ + if (__predict_false(td == NULL)) + cpu_throw(td, newtd); /* doesn't return */ + else + cpu_switch(td, newtd, TDQ_LOCKPTR(tdq)); } /* |