[PATCH 2/2] ethdev: cleanup shared data with the last port

[David Marchand]

If no port is allocated, ethdev (from a primary process) can release the
memzone used to store port data.
This makes it possible for the DPDK memory allocator to release
associated resources back to the OS.

Signed-off-by: David Marchand <david.march...@redhat.com>
---
 lib/ethdev/ethdev_driver.c  |  6 ++++++
 lib/ethdev/ethdev_private.c | 16 +++++++++++++++-
 lib/ethdev/ethdev_private.h |  3 +++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/lib/ethdev/ethdev_driver.c b/lib/ethdev/ethdev_driver.c
index 5bb9c3f97c..c650421c3a 100644
--- a/lib/ethdev/ethdev_driver.c
+++ b/lib/ethdev/ethdev_driver.c
@@ -113,6 +113,8 @@ rte_eth_dev_allocate(const char *name)
        eth_dev->data->backer_port_id = RTE_MAX_ETHPORTS;
        eth_dev->data->mtu = RTE_ETHER_MTU;
        pthread_mutex_init(&eth_dev->data->flow_ops_mutex, NULL);
+       RTE_ASSERT(rte_eal_process_type() == RTE_PROC_PRIMARY);
+       eth_dev_shared_data->allocated_count++;
 
 unlock:
        rte_spinlock_unlock(rte_mcfg_ethdev_get_lock());
@@ -253,6 +255,10 @@ rte_eth_dev_release_port(struct rte_eth_dev *eth_dev)
                rte_free(eth_dev->data->dev_private);
                pthread_mutex_destroy(&eth_dev->data->flow_ops_mutex);
                memset(eth_dev->data, 0, sizeof(struct rte_eth_dev_data));
+
+               eth_dev_shared_data->allocated_count--;
+               if (eth_dev_shared_data->allocated_count == 0)
+                       eth_dev_shared_data_release();
        }
 
        rte_spinlock_unlock(rte_mcfg_ethdev_get_lock());
diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
index 6756625729..6fe2e37c56 100644
--- a/lib/ethdev/ethdev_private.c
+++ b/lib/ethdev/ethdev_private.c
@@ -11,6 +11,7 @@
 
 static const char *MZ_RTE_ETH_DEV_DATA = "rte_eth_dev_data";
 
+static const struct rte_memzone *eth_dev_shared_mz;
 struct eth_dev_shared *eth_dev_shared_data;
 
 /* spinlock for eth device callbacks */
@@ -324,7 +325,7 @@ eth_dev_shared_data_prepare(void)
        const unsigned int flags = 0;
        const struct rte_memzone *mz;
 
-       if (eth_dev_shared_data == NULL) {
+       if (eth_dev_shared_mz == NULL) {
                if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
                        /* Allocate port data and ownership shared memory. */
                        mz = rte_memzone_reserve(MZ_RTE_ETH_DEV_DATA,
@@ -335,16 +336,29 @@ eth_dev_shared_data_prepare(void)
                if (mz == NULL)
                        rte_panic("Cannot allocate ethdev shared data\n");
 
+               eth_dev_shared_mz = mz;
                eth_dev_shared_data = mz->addr;
                if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
                        eth_dev_shared_data->next_owner_id =
                                        RTE_ETH_DEV_NO_OWNER + 1;
+                       eth_dev_shared_data->allocated_count = 0;
                        memset(eth_dev_shared_data->data, 0,
                               sizeof(eth_dev_shared_data->data));
                }
        }
 }
 
+void
+eth_dev_shared_data_release(void)
+{
+       RTE_ASSERT(rte_eal_process_type() == RTE_PROC_PRIMARY);
+       if (eth_dev_shared_mz != NULL) {
+               rte_memzone_free(eth_dev_shared_mz);
+               eth_dev_shared_mz = NULL;
+               eth_dev_shared_data = NULL;
+       }
+}
+
 void
 eth_dev_rxq_release(struct rte_eth_dev *dev, uint16_t qid)
 {
diff --git a/lib/ethdev/ethdev_private.h b/lib/ethdev/ethdev_private.h
index f7706e6a95..c456ba9a50 100644
--- a/lib/ethdev/ethdev_private.h
+++ b/lib/ethdev/ethdev_private.h
@@ -15,6 +15,7 @@
 
 struct eth_dev_shared {
        uint64_t next_owner_id;
+       uint64_t allocated_count;
        struct rte_eth_dev_data data[RTE_MAX_ETHPORTS];
 };
 
@@ -69,6 +70,8 @@ void eth_dev_fp_ops_setup(struct rte_eth_fp_ops *fpo,
 
 void eth_dev_shared_data_prepare(void)
        __rte_exclusive_locks_required(rte_mcfg_ethdev_get_lock());
+void eth_dev_shared_data_release(void)
+       __rte_exclusive_locks_required(rte_mcfg_ethdev_get_lock());
 
 void eth_dev_rxq_release(struct rte_eth_dev *dev, uint16_t qid);
 void eth_dev_txq_release(struct rte_eth_dev *dev, uint16_t qid);
-- 
2.41.0