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

[Leon Romanovsky <leon@kernel.org>]

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On Wed, Jun 01, 2016 at 10:38:12AM -0400, Mike Marciniszyn wrote:
> Upstream commit 7049de65c9e5 into 4.6.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Is it part of the commit message?

> 
> 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.
> 
> 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>
> ---
>  drivers/staging/rdma/hfi1/qp.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rdma/hfi1/qp.c b/drivers/staging/rdma/hfi1/qp.c
> index dc9119e..0401955 100644
> --- a/drivers/staging/rdma/hfi1/qp.c
> +++ b/drivers/staging/rdma/hfi1/qp.c
> @@ -512,6 +512,7 @@ static void iowait_wakeup(struct iowait *wait, int reason)
>  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 iowait *wait)
>  	 * 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);
>  }
>  
>  /**
> 
> --
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