[dpdk-dev] [PATCH] net/enic: allocate stats DMA buffer upfront during probe

[John Daley <johndale@cisco.com>]

From: Hyong Youb Kim <hyonkim@cisco.com>

The driver provides a DMA buffer to the firmware when it requests port
stats. The NIC then fills that buffer with latest stats. Currently,
the driver allocates the DMA buffer the first time it requests stats
and saves it for later use. This can lead to crashes when
primary/secondary processes are involved. For example, the following
sequence crashes the secondary process.

1. Start a primary app that does not call rte_eth_stats_get()
2. dpdk-procinfo -- --stats

dpdk-procinfo crashes while trying to allocate the stats DMA buffer
because the alloc function pointer (vdev.alloc_consistent) is valid
only in the primary process, not in the secondary process.

Overwriting the alloc function pointer in the secondary process is not
an option, as it will simply make the pointer invalid in the primary
process. Instead, allocate the DMA buffer during probe so that only
the primary process does both allocate and free. This allows the
secondary process to dump stats as well.

Cc: stable@dpdk.org
Fixes: 9913fbb91df0 ("enic/base: common code")

Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>
---
 drivers/net/enic/base/vnic_dev.c | 24 ++++++++++++++----------
 drivers/net/enic/base/vnic_dev.h |  1 +
 drivers/net/enic/enic_main.c     |  9 +++++++++
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/net/enic/base/vnic_dev.c b/drivers/net/enic/base/vnic_dev.c
index 05b595eb8..1f8d222fc 100644
--- a/drivers/net/enic/base/vnic_dev.c
+++ b/drivers/net/enic/base/vnic_dev.c
@@ -587,17 +587,9 @@ int vnic_dev_stats_dump(struct vnic_dev *vdev, struct vnic_stats **stats)
 {
 	u64 a0, a1;
 	int wait = 1000;
-	static u32 instance;
-	char name[NAME_MAX];
 
-	if (!vdev->stats) {
-		snprintf((char *)name, sizeof(name),
-			"vnic_stats-%u", instance++);
-		vdev->stats = vdev->alloc_consistent(vdev->priv,
-			sizeof(struct vnic_stats), &vdev->stats_pa, (u8 *)name);
-		if (!vdev->stats)
-			return -ENOMEM;
-	}
+	if (!vdev->stats)
+		return -ENOMEM;
 
 	*stats = vdev->stats;
 	a0 = vdev->stats_pa;
@@ -922,6 +914,18 @@ u32 vnic_dev_get_intr_coal_timer_max(struct vnic_dev *vdev)
 	return vdev->intr_coal_timer_info.max_usec;
 }
 
+int vnic_dev_alloc_stats_mem(struct vnic_dev *vdev)
+{
+	char name[NAME_MAX];
+	static u32 instance;
+
+	snprintf((char *)name, sizeof(name), "vnic_stats-%u", instance++);
+	vdev->stats = vdev->alloc_consistent(vdev->priv,
+					     sizeof(struct vnic_stats),
+					     &vdev->stats_pa, (u8 *)name);
+	return vdev->stats == NULL ? -ENOMEM : 0;
+}
+
 void vnic_dev_unregister(struct vnic_dev *vdev)
 {
 	if (vdev) {
diff --git a/drivers/net/enic/base/vnic_dev.h b/drivers/net/enic/base/vnic_dev.h
index 8c0992063..7e5736b4d 100644
--- a/drivers/net/enic/base/vnic_dev.h
+++ b/drivers/net/enic/base/vnic_dev.h
@@ -165,6 +165,7 @@ struct vnic_dev *vnic_dev_register(struct vnic_dev *vdev,
 	void *priv, struct rte_pci_device *pdev, struct vnic_dev_bar *bar,
 	unsigned int num_bars);
 struct rte_pci_device *vnic_dev_get_pdev(struct vnic_dev *vdev);
+int vnic_dev_alloc_stats_mem(struct vnic_dev *vdev);
 int vnic_dev_cmd_init(struct vnic_dev *vdev, int fallback);
 int vnic_dev_get_size(void);
 int vnic_dev_int13(struct vnic_dev *vdev, u64 arg, u32 op);
diff --git a/drivers/net/enic/enic_main.c b/drivers/net/enic/enic_main.c
index d4f478b5e..bd4447f01 100644
--- a/drivers/net/enic/enic_main.c
+++ b/drivers/net/enic/enic_main.c
@@ -1478,6 +1478,15 @@ int enic_probe(struct enic *enic)
 		enic_alloc_consistent,
 		enic_free_consistent);
 
+	/*
+	 * Allocate the consistent memory for stats upfront so both primary and
+	 * secondary processes can dump stats.
+	 */
+	err = vnic_dev_alloc_stats_mem(enic->vdev);
+	if (err) {
+		dev_err(enic, "Failed to allocate cmd memory, aborting\n");
+		goto err_out_unregister;
+	}
 	/* Issue device open to get device in known state */
 	err = enic_dev_open(enic);
 	if (err) {
-- 
2.12.0