linux-kernel - [PATCH] vdpa/mlx5: fix error handling in mlx5_vdpa_dev

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Date:   Fri,  7 Jan 2022 13:13:52 -0800
From:   trix@...hat.com
To:     mst@...hat.com, jasowang@...hat.com, nathan@...nel.org,
        ndesaulniers@...gle.com, elic@...dia.com, parav@...dia.com,
        si-wei.liu@...cle.com, xieyongji@...edance.com
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Tom Rix <trix@...hat.com>
Subject: [PATCH] vdpa/mlx5: fix error handling in mlx5_vdpa_dev_add()

From: Tom Rix <trix@...hat.com>

Clang build fails with
mlx5_vnet.c:2574:6: error: variable 'mvdev' is used uninitialized whenever
  'if' condition is true
        if (!ndev->vqs || !ndev->event_cbs) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mlx5_vnet.c:2660:14: note: uninitialized use occurs here
        put_device(&mvdev->vdev.dev);
                    ^~~~~
This because mvdev is set after trying to allocate ndev->vqs,event_cbs.
So move the allocation to after mvdev is set but before the arrays
are used in init_mvqs()

Fixes: 7620d51af29a ("vdpa/mlx5: Support configuring max data virtqueue")
Signed-off-by: Tom Rix <trix@...hat.com>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index b564c70475815..37220f6db7ad7 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2569,16 +2569,18 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
 	if (IS_ERR(ndev))
 		return PTR_ERR(ndev);
 
+	ndev->mvdev.mlx_features = mgtdev->mgtdev.supported_features;
+	ndev->mvdev.max_vqs = max_vqs;
+	mvdev = &ndev->mvdev;
+	mvdev->mdev = mdev;
+
 	ndev->vqs = kcalloc(max_vqs, sizeof(*ndev->vqs), GFP_KERNEL);
 	ndev->event_cbs = kcalloc(max_vqs + 1, sizeof(*ndev->event_cbs), GFP_KERNEL);
 	if (!ndev->vqs || !ndev->event_cbs) {
 		err = -ENOMEM;
 		goto err_alloc;
 	}
-	ndev->mvdev.mlx_features = mgtdev->mgtdev.supported_features;
-	ndev->mvdev.max_vqs = max_vqs;
-	mvdev = &ndev->mvdev;
-	mvdev->mdev = mdev;
+
 	init_mvqs(ndev);
 	mutex_init(&ndev->reslock);
 	config = &ndev->config;
-- 
2.26.3