FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

[gregkh]

The patch below does not apply to the 4.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 2aee309d3e01447c55fdf89cef05a0e2be372655 Mon Sep 17 00:00:00 2001
From: Mike Marciniszyn <mike.marciniszyn@intel.com>
Date: Fri, 17 Jun 2016 19:17:49 -0700
Subject: [PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path

A failure in the get_txreq() inline will result in a
slow path retry using __get_txreq().

__get_txreq() attempts to procure the qp s_lock, which
is already held in all callers.

Fix by deleting the s_lock maintenance in __get_txreq()
and add sparse syntax hooks to future proof the code.

Cc: Stable <stable@vger.kernel.org> # 4.6+
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@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>

diff --git a/drivers/infiniband/hw/hfi1/verbs_txreq.c b/drivers/infiniband/hw/hfi1/verbs_txreq.c
index bc95c4112c61..d8fb056526f8 100644
--- a/drivers/infiniband/hw/hfi1/verbs_txreq.c
+++ b/drivers/infiniband/hw/hfi1/verbs_txreq.c
@@ -92,11 +92,10 @@ void hfi1_put_txreq(struct verbs_txreq *tx)
 
 struct verbs_txreq *__get_txreq(struct hfi1_ibdev *dev,
 				struct rvt_qp *qp)
+	__must_hold(&qp->s_lock)
 {
 	struct verbs_txreq *tx = ERR_PTR(-EBUSY);
-	unsigned long flags;
 
-	spin_lock_irqsave(&qp->s_lock, flags);
 	write_seqlock(&dev->iowait_lock);
 	if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) {
 		struct hfi1_qp_priv *priv;
@@ -116,7 +115,6 @@ struct verbs_txreq *__get_txreq(struct hfi1_ibdev *dev,
 	}
 out:
 	write_sequnlock(&dev->iowait_lock);
-	spin_unlock_irqrestore(&qp->s_lock, flags);
 	return tx;
 }
 
diff --git a/drivers/infiniband/hw/hfi1/verbs_txreq.h b/drivers/infiniband/hw/hfi1/verbs_txreq.h
index 1cf69b2fe4a5..a1d6e0807f97 100644
--- a/drivers/infiniband/hw/hfi1/verbs_txreq.h
+++ b/drivers/infiniband/hw/hfi1/verbs_txreq.h
@@ -73,6 +73,7 @@ struct verbs_txreq *__get_txreq(struct hfi1_ibdev *dev,
 
 static inline struct verbs_txreq *get_txreq(struct hfi1_ibdev *dev,
 					    struct rvt_qp *qp)
+	__must_hold(&qp->slock)
 {
 	struct verbs_txreq *tx;
 	struct hfi1_qp_priv *priv = qp->priv;

RE: FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

[Marciniszyn, Mike]

> The patch below does not apply to the 4.6-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h

A 4.6 version is in http://marc.info/?l=linux-rdma&m=146904918032092&w=2.

Oddly it cherry-picked for me ok.  Is this due to a flaw in the stable triggering method in the upstream patch?

Mike

Re: FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

[gregkh]

On Wed, Jul 20, 2016 at 09:17:30PM +0000, Marciniszyn, Mike wrote:
> > The patch below does not apply to the 4.6-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > thanks,
> > 
> > greg k-h
> 
> A 4.6 version is in http://marc.info/?l=linux-rdma&m=146904918032092&w=2.

I can't do much with a web-link, can you send me the patch?

> Oddly it cherry-picked for me ok.  Is this due to a flaw in the stable triggering method in the upstream patch?

Hm, if cherry-pick worked, that's a huge hint, can you send me the
cherry-picked patch output?  Odds are git can handle a merge issue
better than quilt can.

thanks,

greg k-h

RE: FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

[Marciniszyn, Mike]

> > A 4.6 version is in http://marc.info/?l=linux-rdma&m=146904918032092&w=2.
> 
> I can't do much with a web-link, can you send me the patch?

The web link was intended as an FYI.

I submitting the actual patch to stable@vger.kernel.org.

Mike

RE: FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq allocation slow path" failed to apply to 4.6-stable tree

[Marciniszyn, Mike]

> Subject: RE: FAILED: patch "[PATCH] IB/hfi1: Fix deadlock with txreq
> allocation slow path" failed to apply to 4.6-stable tree
> 
> 
> > > A 4.6 version is in http://marc.info/?l=linux-
> rdma&m=146904918032092&w=2.
> >
> > I can't do much with a web-link, can you send me the patch?
> 
> The web link was intended as an FYI.
> 
> I submitting the actual patch to stable@vger.kernel.org.
> 

Were you able to see this patch on the list?

Mike