[PATCH 4.6 121/121] IB/hfi1: Fix hard lockup due to not using save/restore spin lock

Greg Kroah-Hartman
2016-06-05T22:22:46Z

From: Mike Marciniszyn <mike.marciniszyn@intel.com>

commit 7049de65c9e520886f06d6f9deceaaed5d93fb7c upstream.

Commit b9b06cb6feda
("IB/hfi1: Fix missing lock/unlock in verbs drain callback")
added a spin lock.

Unfortunately, the new lock code can be called from a base
level interrupt state, and an interrupt that can get stacked
will attempt to get the same lock.

Fix by using the flag save/restore spin lock variation.

Cc: stable@vger.kernel.org # 4.6+
Reviewed-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/rdma/hfi1/qp.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/rdma/hfi1/qp.c
+++ b/drivers/staging/rdma/hfi1/qp.c
@@ -512,6 +512,7 @@ static void iowait_wakeup(struct iowait
static void iowait_sdma_drained(struct iowait *wait)
{
struct rvt_qp *qp = iowait_to_qp(wait);
+ unsigned long flags;

/*
* This happens when the send engine notes
@@ -519,12 +520,12 @@ static void iowait_sdma_drained(struct i
* do the flush work until that QP's
* sdma work has finished.
*/
- spin_lock(&qp->s_lock);
+ spin_lock_irqsave(&qp->s_lock, flags);
if (qp->s_flags & RVT_S_WAIT_DMA) {
qp->s_flags &= ~RVT_S_WAIT_DMA;
hfi1_schedule_send(qp);
}
- spin_unlock(&qp->s_lock);
+ spin_unlock_irqrestore(&qp->s_lock, flags);
}

/**