[PATCH net-next v2 02/15] ibmveth: Refactor buffer pool management for per-queue MQ RX
From: Mingming Cao <hidden>
Date: 2026-07-01 22:25:38
Also in:
netdev
Subsystem:
ibm power virtual ethernet device driver, linux for powerpc (32-bit and 64-bit), networking drivers, the rest · Maintainers:
Nick Child, Madhavan Srinivasan, Michael Ellerman, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This is the key memory-model change for MQ RX.
Legacy ibmveth uses five adapter-level RX buffer pools (512 B
through 64 KiB slots). pool_active[] enables the standard-MTU pools by
default; larger pools activate when MTU requires them. With single-queue
RX that set is shared on one completion path.
MQ requires the same pool model per queue: buffers post with
H_ADD_LOGICAL_LAN_BUFFERS_QUEUE against a queue handle and completions
return on that queue. Sharing pools across queues would mix ownership and
break queue-local replenish/drain/teardown.
Refactor around queue-local pools with static geometry (still defined at
probe on queue 0, copied to queues 1..N at alloc time):
rx_buff_pool[queue][pool]
ibmveth_alloc_queue_buffer_pools()
ibmveth_free_queue_buffer_pools()
ibmveth_alloc_buffer_pools() / ibmveth_free_buffer_pools()
Queue 0 remains the template for pool geometry (size, buff_size,
threshold, active). For queues 1..N we copy metadata from queue 0, then
allocate actual backing arrays/skbs per queue.
At the default 1500-byte MTU, pool 4 (64 KiB buffers) is not needed and
costs guest memory when allocated per queue in MQ mode. Clear
pool_active[4] so open() skips it; ibmveth_change_mtu() still enables
larger pools when MTU warrants jumbo frames.
Error handling is also made queue-safe:
- if allocation fails in one pool, unwind only what was allocated for
that queue, then unwind prior queues in the caller
- free paths release pools based on real allocations
(free_map/dma_addr/skbuff), not only pool->active
That allocation-based free check is intentional: later resize and failure
paths can leave memory allocated even when active was already cleared.
Freeing by allocation state avoids leaks and double-free corner cases.
This split keeps the per-queue pool design isolated and reviewable ahead
of the MQ datapath enable commit later in the series.
Signed-off-by: Mingming Cao <redacted>
Reviewed-by: Dave Marquardt <redacted>
---
drivers/net/ethernet/ibm/ibmveth.c | 127 +++++++++++++++++++++++++++++
drivers/net/ethernet/ibm/ibmveth.h | 2 +-
2 files changed, 128 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index b8adc9935471..95068fb20dba 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c@@ -611,6 +611,133 @@ static void ibmveth_free_buffer_pool(struct ibmveth_adapter *adapter, } } +/** + * ibmveth_alloc_queue_buffer_pools - Allocate buffer pools for a single queue + * @adapter: ibmveth adapter structure + * @queue: queue index + * + * Allocates all active buffer pools for the specified queue. + * Pool metadata must be initialized before calling this function. + * + * Return: 0 on success, negative error code on failure + */ +static int ibmveth_alloc_queue_buffer_pools(struct ibmveth_adapter *adapter, + int queue) +{ + struct net_device *netdev = adapter->netdev; + int i; + + for (i = 0; i < IBMVETH_NUM_BUFF_POOLS; i++) { + if (!adapter->rx_buff_pool[queue][i].active) + continue; + + if (ibmveth_alloc_buffer_pool(&adapter->rx_buff_pool[queue][i])) { + netdev_err(netdev, + "unable to allocate buffer pool %d for queue %d (size=%u, count=%u)\n", + i, queue, + adapter->rx_buff_pool[queue][i].buff_size, + adapter->rx_buff_pool[queue][i].size); + adapter->rx_buff_pool[queue][i].active = 0; + + /* Free pools allocated so far for this queue */ + while (--i >= 0) { + if (adapter->rx_buff_pool[queue][i].active) + ibmveth_free_buffer_pool(adapter, + &adapter->rx_buff_pool[queue][i]); + } + return -ENOMEM; + } + } + + return 0; +} + +/** + * ibmveth_free_queue_buffer_pools - Free buffer pools for a single queue + * @adapter: ibmveth adapter structure + * @queue: queue index + * + * Frees all active buffer pools for the specified queue. + */ +static void ibmveth_free_queue_buffer_pools(struct ibmveth_adapter *adapter, + int queue) +{ + int i; + + for (i = 0; i < IBMVETH_NUM_BUFF_POOLS; i++) { + struct ibmveth_buff_pool *pool = &adapter->rx_buff_pool[queue][i]; + + /* Free pool if it has allocated memory, regardless of active flag. + * Pools may have memory allocated but not marked active during + * queue scale-up, so we must check for actual allocations. + */ + if (pool->free_map || pool->dma_addr || pool->skbuff) + ibmveth_free_buffer_pool(adapter, pool); + } +} + +/** + * ibmveth_alloc_buffer_pools - Allocate buffer pools for all queues + * @adapter: ibmveth adapter structure + * + * Initializes pool metadata for queues 1-N from queue 0 settings, + * then allocates buffer pools for all queues using the helper function. + * + * Return: 0 on success, negative error code on failure + */ +static int __maybe_unused ibmveth_alloc_buffer_pools(struct ibmveth_adapter *adapter) +{ + struct net_device *netdev = adapter->netdev; + int i, q, rc; + + /* Initialize pool metadata for queues 1-15 from queue 0 settings */ + for (q = 1; q < adapter->num_rx_queues; q++) { + for (i = 0; i < IBMVETH_NUM_BUFF_POOLS; i++) { + struct ibmveth_buff_pool *src = &adapter->rx_buff_pool[0][i]; + struct ibmveth_buff_pool *dst = &adapter->rx_buff_pool[q][i]; + + dst->size = src->size; + dst->index = src->index; + dst->buff_size = src->buff_size; + dst->threshold = src->threshold; + dst->active = src->active; + } + } + + /* Allocate actual buffers for all queues */ + for (q = 0; q < adapter->num_rx_queues; q++) { + rc = ibmveth_alloc_queue_buffer_pools(adapter, q); + if (rc) { + /* Free pools for all previous queues */ + while (--q >= 0) + ibmveth_free_queue_buffer_pools(adapter, q); + return rc; + } + } + + netdev_dbg(netdev, "allocated buffer pools for %d queue(s)\n", + adapter->num_rx_queues); + return 0; +} + +/** + * ibmveth_free_buffer_pools - Free buffer pools for all queues + * @adapter: ibmveth adapter structure + * + * Frees buffer pools for all queues using the helper function. + */ +static void __maybe_unused ibmveth_free_buffer_pools(struct ibmveth_adapter *adapter) +{ + int q; + + /* Free buffer pools for all queues */ + for (q = 0; q < adapter->num_rx_queues; q++) + ibmveth_free_queue_buffer_pools(adapter, q); + + netdev_dbg(adapter->netdev, "freed buffer pools for %d queue(s)\n", + adapter->num_rx_queues); +} + /** * ibmveth_remove_buffer_from_pool - remove a buffer from a pool * @adapter: adapter instance
diff --git a/drivers/net/ethernet/ibm/ibmveth.h b/drivers/net/ethernet/ibm/ibmveth.h
index f0dffe42e8fe..d2ceeccd5fbd 100644
--- a/drivers/net/ethernet/ibm/ibmveth.h
+++ b/drivers/net/ethernet/ibm/ibmveth.h@@ -286,7 +286,7 @@ static inline long h_illan_attributes(unsigned long unit_address, static int pool_size[] = { 512, 1024 * 2, 1024 * 16, 1024 * 32, 1024 * 64 }; static int pool_count[] = { 256, 512, 256, 256, 256 }; static int pool_count_cmo[] = { 256, 512, 256, 256, 64 }; -static int pool_active[] = { 1, 1, 0, 0, 1}; +static int pool_active[] = { 1, 1, 0, 0, 0}; #define IBM_VETH_INVALID_MAP ((u16)0xffff)
--
2.39.3 (Apple Git-146)