[dpdk-stable] patch 'net/mlx5: fix memory regions release deadlock' has been queued to stable release 19.11.1

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 19.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/13/20. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Thanks.

Luca Boccassi

---
>From f6f7ba7a7c7567211b779e7ff2bb816b10c3554b Mon Sep 17 00:00:00 2001
From: Michael Baum <michaelba at mellanox.com>
Date: Tue, 4 Feb 2020 15:36:09 +0200
Subject: [PATCH] net/mlx5: fix memory regions release deadlock

[ upstream commit 4f8e6befe7c6045b082dc5b95afd5a1c00e30bf0 ]

The mpx5 PMD maintains the list of devices for those the memory
operation callback routines must be invoked to keep the device MRs (MR
is the entity backing the hardware DMA transactions) consistent with the
mapped memory.
Each device context in the list is protected with dedicated lock on per
device basis, which might be taken inside the callback routine.

When device is closing the PMD frees all MRs by calling
mlx5_mr_release(), that might call rte_free() under the taken device
lock.  If this rte_free call triggers the entire memory segment freeing
it, in its turn, invokes the callback routine and attempt to take the
lock inside this one causes the deadlock.

The patch proposes the remove the device from the callback list first
and then call mlx5_mr_release() and free the remaining device MRs
explicitly.

Fixes: 0e3d0525b2f2 ("net/mlx5: fix memory event callback list")

Signed-off-by: Michael Baum <michaelba at mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
Acked-by: Matan Azrad <matan at mellanox.com>
---
 drivers/net/mlx5/mlx5.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 50960c91ce..646d50285b 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -673,12 +673,12 @@ mlx5_free_shared_ibctx(struct mlx5_ibv_shared *sh)
 	assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
 	if (--sh->refcnt)
 		goto exit;
-	/* Release created Memory Regions. */
-	mlx5_mr_release(sh);
 	/* Remove from memory callback device list. */
 	rte_rwlock_write_lock(&mlx5_shared_data->mem_event_rwlock);
 	LIST_REMOVE(sh, mem_event_cb);
 	rte_rwlock_write_unlock(&mlx5_shared_data->mem_event_rwlock);
+	/* Release created Memory Regions. */
+	mlx5_mr_release(sh);
 	/* Remove context from the global device list. */
 	LIST_REMOVE(sh, next);
 	/*
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-02-11 11:17:44.595538811 +0000
+++ 0173-net-mlx5-fix-memory-regions-release-deadlock.patch	2020-02-11 11:17:38.812009050 +0000
@@ -1,8 +1,10 @@
-From 4f8e6befe7c6045b082dc5b95afd5a1c00e30bf0 Mon Sep 17 00:00:00 2001
+From f6f7ba7a7c7567211b779e7ff2bb816b10c3554b Mon Sep 17 00:00:00 2001
 From: Michael Baum <michaelba at mellanox.com>
 Date: Tue, 4 Feb 2020 15:36:09 +0200
 Subject: [PATCH] net/mlx5: fix memory regions release deadlock
 
+[ upstream commit 4f8e6befe7c6045b082dc5b95afd5a1c00e30bf0 ]
+
 The mpx5 PMD maintains the list of devices for those the memory
 operation callback routines must be invoked to keep the device MRs (MR
 is the entity backing the hardware DMA transactions) consistent with the
@@ -21,7 +23,6 @@
 explicitly.
 
 Fixes: 0e3d0525b2f2 ("net/mlx5: fix memory event callback list")
-Cc: stable at dpdk.org
 
 Signed-off-by: Michael Baum <michaelba at mellanox.com>
 Acked-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
@@ -31,11 +32,11 @@
  1 file changed, 2 insertions(+), 2 deletions(-)
 
 diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
-index 7a79722fb7..b4ec6cba1a 100644
+index 50960c91ce..646d50285b 100644
 --- a/drivers/net/mlx5/mlx5.c
 +++ b/drivers/net/mlx5/mlx5.c
-@@ -679,12 +679,12 @@ mlx5_free_shared_ibctx(struct mlx5_ibv_shared *sh)
- 	MLX5_ASSERT(rte_eal_process_type() == RTE_PROC_PRIMARY);
+@@ -673,12 +673,12 @@ mlx5_free_shared_ibctx(struct mlx5_ibv_shared *sh)
+ 	assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
  	if (--sh->refcnt)
  		goto exit;
 -	/* Release created Memory Regions. */