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Date:      Tue, 17 Jul 2018 10:20:01 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r336398 - head/sys/dev/mlx5/mlx5_core
Message-ID:  <201807171020.w6HAK1IT045660@repo.freebsd.org>
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Author: hselasky
Date: Tue Jul 17 10:20:01 2018
New Revision: 336398
URL: https://svnweb.freebsd.org/changeset/base/336398

Log:
  Make sure the state variable is set atomically instead of using a mutex in mlx5core.
  
  Device detach and setting error state may deadlock over the interface mutex
  like this:
  
  a) Detach code in mlx5en waits until error state is set while the interface
  mutex is locked.
  b) The set error handler needs to lock the interface mutex before it can
  set the error state.
  
  The solution is to use atomics to set the error state.
  
  MFC after:		1 week
  Sponsored by:		Mellanox Technologies

Modified:
  head/sys/dev/mlx5/mlx5_core/mlx5_health.c

Modified: head/sys/dev/mlx5/mlx5_core/mlx5_health.c
==============================================================================
--- head/sys/dev/mlx5/mlx5_core/mlx5_health.c	Tue Jul 17 10:16:32 2018	(r336397)
+++ head/sys/dev/mlx5/mlx5_core/mlx5_health.c	Tue Jul 17 10:20:01 2018	(r336398)
@@ -219,21 +219,19 @@ void mlx5_enter_error_state(struct mlx5_core_dev *dev,
 	u32 fatal_error;
 	int lock = -EBUSY;
 
-	mutex_lock(&dev->intf_state_mutex);
-	if (dev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR) {
-		goto unlock;
-		return;
-	}
-
 	fatal_error = check_fatal_sensors(dev);
 
 	if (fatal_error || force) {
+		if (xchg(&dev->state, MLX5_DEVICE_STATE_INTERNAL_ERROR) ==
+		    MLX5_DEVICE_STATE_INTERNAL_ERROR)
+			return;
 		if (!force)
 			mlx5_core_err(dev, "internal state error detected\n");
-		dev->state = MLX5_DEVICE_STATE_INTERNAL_ERROR;
 		mlx5_trigger_cmd_completions(dev);
 	}
 
+	mutex_lock(&dev->intf_state_mutex);
+
 	if (force)
 		goto err_state_done;
 
@@ -272,7 +270,6 @@ void mlx5_enter_error_state(struct mlx5_core_dev *dev,
 
 err_state_done:
 	mlx5_core_event(dev, MLX5_DEV_EVENT_SYS_ERROR, 0);
-unlock:
 	mutex_unlock(&dev->intf_state_mutex);
 }

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