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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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6efaf10f16
The memory barrier is not enough to protect queuing works into
a destroyed cq kthread. Just imagine the following situation:
CPU1 CPU2
rvt_cq_enter()
worker = cq->rdi->worker;
rvt_cq_exit()
rdi->worker = NULL;
smp_wmb();
kthread_flush_worker(worker);
kthread_stop(worker->task);
kfree(worker);
// nothing queued yet =>
// nothing flushed and
// happily stopped and freed
if (likely(worker)) {
// true => read before CPU2 acted
cq->notify = RVT_CQ_NONE;
cq->triggered++;
kthread_queue_work(worker, &cq->comptask);
BANG: worker has been flushed/stopped/freed in the meantime.
This patch solves this by protecting the critical sections by
rdi->n_cqs_lock. It seems that this lock is not much contended
and looks reasonable for this purpose.
One catch is that rvt_cq_enter() might be called from IRQ context.
Therefore we must always take the lock with IRQs disabled to avoid
a possible deadlock.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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|---|---|---|
| .. | ||
| ah.c | ||
| ah.h | ||
| cq.c | ||
| cq.h | ||
| dma.c | ||
| dma.h | ||
| Kconfig | ||
| mad.c | ||
| mad.h | ||
| Makefile | ||
| mcast.c | ||
| mcast.h | ||
| mmap.c | ||
| mmap.h | ||
| mr.c | ||
| mr.h | ||
| pd.c | ||
| pd.h | ||
| qp.c | ||
| qp.h | ||
| srq.c | ||
| srq.h | ||
| trace_mr.h | ||
| trace_qp.h | ||
| trace_rvt.h | ||
| trace_tx.h | ||
| trace.c | ||
| trace.h | ||
| vt.c | ||
| vt.h | ||