On 8/6/26 11:37 AM, Jakub Kicinski wrote:
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---
ibmveth: Refactor RX resource allocation for MQ RX bring-up
This moves the filter list and per-queue RX ring allocation out of
ibmveth_open() into four new helpers, and wires them into both the
open error unwind and ibmveth_close(). Runtime behaviour is meant to
stay single-queue since num_rx_queues is still 1.
Hi Jakub,
Thanks for the review.
diff --git a/drivers/net/ethernet/ibm/ibmveth.c
b/drivers/net/ethernet/ibm/ibmveth.c
index 8e758362cb263..1007dd95cde02 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -151,6 +151,184 @@ static unsigned int ibmveth_real_max_tx_queues(void)
return min(n_cpu, IBMVETH_MAX_QUEUES);
}
+/**
+ * ibmveth_alloc_filter_list - Allocate and map filter list
+ * @adapter: ibmveth adapter structure
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int
+ibmveth_alloc_filter_list(struct ibmveth_adapter *adapter)
+{
+ struct device *dev = &adapter->vdev->dev;
+ struct net_device *netdev = adapter->netdev;
+
+ adapter->filter_list_addr = (void *)get_zeroed_page(GFP_KERNEL);
+ if (!adapter->filter_list_addr) {
+ netdev_err(netdev, "unable to allocate filter pages\n");
+ return -ENOMEM;
+ }
+
+ adapter->filter_list_dma = dma_map_single(dev,
+ adapter->filter_list_addr,
+ 4096, DMA_BIDIRECTIONAL);
+ if (dma_mapping_error(dev, adapter->filter_list_dma)) {
+ netdev_err(netdev, "unable to map filter list pages\n");
+ free_page((unsigned long)adapter->filter_list_addr);
+ adapter->filter_list_addr = NULL;
+ return -ENOMEM;
+ }
[Severity: Medium]
Should this error path also clear adapter->filter_list_dma? On failure
dma_map_single() has stored DMA_MAPPING_ERROR, which is ~(dma_addr_t)0 and
therefore non-zero, and only filter_list_addr is reset here.
Yes. In v5 I will clear `filter_list_dma` on mapping error, matching the
existing `buffer_list_dma` convention.
The sibling helper added in the same patch does zero the cookie in the
same situation:
if (dma_mapping_error(dev, adapter->buffer_list_dma[i])) {
...
adapter->buffer_list_dma[i] = 0;
goto err_cleanup;
}
so the two new helpers appear to disagree on the convention.
+
+ netdev_dbg(netdev, "filter list @ 0x%p (DMA: 0x%llx)\n",
+ adapter->filter_list_addr,
+ (unsigned long long)adapter->filter_list_dma);
+
+ return 0;
+}
+
+/**
+ * ibmveth_free_filter_list - Free filter list resources
+ * @adapter: ibmveth adapter structure
+ */
+static void
+ibmveth_free_filter_list(struct ibmveth_adapter *adapter)
+{
+ struct device *dev = &adapter->vdev->dev;
+
+ if (adapter->filter_list_dma) {
+ dma_unmap_single(dev, adapter->filter_list_dma, 4096,
+ DMA_BIDIRECTIONAL);
+ adapter->filter_list_dma = 0;
+ }
[Severity: Medium]
Can this unmap the DMA_MAPPING_ERROR sentinel? ibmveth_free_filter_list()
treats any non-zero filter_list_dma as a live mapping, and the mapping-error
branch of ibmveth_alloc_filter_list() leaves the sentinel behind.
The state looks reachable without dev_close(). ibmveth_set_csum_offload(),
ibmveth_set_tso(), ibmveth_change_mtu() and veth_pool_store() all call
ibmveth_close() and then ibmveth_open() directly while netif_running() is
still true:
if (netif_running(dev)) {
restart = 1;
ibmveth_close(dev);
}
...
if (restart)
rc2 = ibmveth_open(dev);
If that re-open fails at the dma_mapping_error() check in
ibmveth_alloc_filter_list(), open() returns through the out: label without
calling ibmveth_free_filter_list(), so the adapter is left with
filter_list_addr == NULL and filter_list_dma == DMA_MAPPING_ERROR while the
netdev is still marked running. A later "ip link set dev ethX down" then
reaches ndo_stop == ibmveth_close() -> ibmveth_free_filter_list() and unmaps
that invalid address.
On pseries the dma_iommu path catches this in iommu_free_check(), which emits
a ratelimited "iommu_free: invalid entry" message and a WARN_ON(1) (a panic
with panic_on_warn set), so no TCE state is changed, but the backtrace is
still user triggerable with CAP_NET_ADMIN plus a mapping failure.
Setting adapter->filter_list_dma = 0 in that error branch, matching
ibmveth_alloc_rx_queues(), would make the guard here reliable.
This is still present unchanged at the end of the series (a3781f4ae789), so
a later patch does not appear to address it.
Yes. The failure path here is:
- `dma_map_single()` fails for the filter page
- open/reopen leaves `filter_list_addr = NULL`
- `filter_list_dma` is still left at `DMA_MAPPING_ERROR`
- a later free path sees a non-zero DMA handle and calls
`dma_unmap_single()` on the sentinel value
That leads to the later bad unmap/WARN.
In v5 I will free the page and set `adapter->filter_list_dma = 0` on
mapping error while keeping `filter_list_addr = NULL`, so the free path
remains consistent and only unmaps real mappings.
+
+ if (adapter->filter_list_addr) {
+ free_page((unsigned long)adapter->filter_list_addr);
+ adapter->filter_list_addr = NULL;
+ }
+}
+
[ ... ]
+ adapter->buffer_list_dma[i] =
+ dma_map_single(dev, adapter->buffer_list_addr[i],
+ 4096, DMA_BIDIRECTIONAL);
+ if (dma_mapping_error(dev, adapter->buffer_list_dma[i])) {
+ netdev_err(netdev,
+ "unable to map buffer list for queue %d\n",
+ i);
+ adapter->buffer_list_dma[i] = 0;
+ goto err_cleanup;
+ }
+
[ ... ]
@@ -627,74 +805,34 @@ static int ibmveth_open(struct net_device *netdev)
- rc = -ENOMEM;
- adapter->buffer_list_addr[0] = (void *)get_zeroed_page(GFP_KERNEL);
- if (!adapter->buffer_list_addr[0]) {
- netdev_err(netdev, "unable to allocate list pages\n");
+ rc = ibmveth_alloc_filter_list(adapter);
+ if (rc)
goto out;
- }
[ ... ]
@@ -753,26 +889,12 @@ static int ibmveth_open(struct net_device *netdev)
+ ibmveth_cleanup_rx_resources(adapter);
out_free_filter_list:
- free_page((unsigned long)adapter->filter_list_addr);
-out_free_buffer_list:
- free_page((unsigned long)adapter->buffer_list_addr[0]);
+ ibmveth_free_filter_list(adapter);
out:
napi_disable(&adapter->napi[0]);
return rc;
[ ... ]
Thanks again for the review,
Mingming
