[PATCH] net/mlx5: fix crash when secondary queries dev info after primary exits

[Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>]

When the primary process exits, the shared mlx5 state becomes
unavailable to secondary processes. If a secondary process attempts
to query device information (e.g., via testpmd), a NULL dereference
may occur due to missing shared data.

This patch adds a check for shared context availability and fails
gracefully while preventing a crash.

Fixes: e60fbd5b24fc ("mlx5: add device configure/start/stop")
Cc: stable@dpdk.org

Signed-off-by: Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>
---
 drivers/net/mlx5/mlx5_ethdev.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 68d1c1bfa7..1848f6536a 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -368,6 +368,12 @@ mlx5_dev_infos_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *info)
 	 * Since we need one CQ per QP, the limit is the minimum number
 	 * between the two values.
 	 */
+	if (priv == NULL || priv->sh == NULL) {
+		DRV_LOG(ERR,
+		"mlx5 shared data unavailable (primary process likely exited)");
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
 	max = RTE_MIN(priv->sh->dev_cap.max_cq, priv->sh->dev_cap.max_qp);
 	/* max_rx_queues is uint16_t. */
 	max = RTE_MIN(max, (unsigned int)UINT16_MAX);
-- 
2.43.0