[PATCH v4 2/2] net/sfc: provide cached dev info to use in secondary process

[Ivan Malov]

Secondary process support in the 'test-pmd' application now requires that
the driver expose the 'dev_infos_get' method within that context. Use the
cached dev info from the primary process in order to meet the requirement.

Signed-off-by: Ivan Malov <ivan.malov at arknetworks.am>
Reviewed-by: Viacheslav Galaktionov <viacheslav.galaktionov at arknetworks.am>
---
 drivers/net/sfc/sfc.h        | 19 ++++++++++++++
 drivers/net/sfc/sfc_ethdev.c | 48 ++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/drivers/net/sfc/sfc.h b/drivers/net/sfc/sfc.h
index 629578549f..809ad59148 100644
--- a/drivers/net/sfc/sfc.h
+++ b/drivers/net/sfc/sfc.h
@@ -156,6 +156,25 @@ struct sfc_adapter_shared {
 	unsigned int			nb_repr_txq;
 
 	struct sfc_nic_dma_info		nic_dma_info;
+
+	/*
+	 * Snapshot of the 'rte_eth_dev_info_get' output created by the primary
+	 * process attach path for the secondary process to use in its own
+	 * implementation of the 'dev_infos_get' method.
+	 *
+	 * Some driver-computed fields derived from mutable post-attach state
+	 * are knowingly stale, which is acceptable for the secondary process.
+	 *
+	 * This also contains a handful of stale fields which are normally
+	 * set by the ethdev layer upon invocation of the 'dev_infos_get',
+	 * so they will be overridden anyway in the secondary process.
+	 */
+	struct rte_eth_dev_info		dev_info_cache;
+	/*
+	 * Set to 'true' by the probe function from the primary process. The
+	 * secondary 'dev_infos_get' returns '-EAGAIN' when this is 'false'.
+	 */
+	RTE_ATOMIC(bool)		dev_info_cache_is_valid;
 };
 
 /* Adapter process private data */
diff --git a/drivers/net/sfc/sfc_ethdev.c b/drivers/net/sfc/sfc_ethdev.c
index 13619b4b9a..02231e4bce 100644
--- a/drivers/net/sfc/sfc_ethdev.c
+++ b/drivers/net/sfc/sfc_ethdev.c
@@ -16,7 +16,9 @@
 #include <bus_pci_driver.h>
 #include <rte_errno.h>
 #include <rte_string_fns.h>
+#include <rte_stdatomic.h>
 #include <rte_bitops.h>
+#include <rte_ethdev.h>
 #include <rte_ether.h>
 
 #include "efx.h"
@@ -3163,7 +3165,32 @@ sfc_eth_dev_clear_ops(struct rte_eth_dev *dev)
 	sa->priv.dp_rx = NULL;
 }
 
+static int
+sfc_dev_infos_get_secondary(struct rte_eth_dev *dev,
+			    struct rte_eth_dev_info *dev_info)
+{
+	const struct sfc_adapter_shared *sas =
+		sfc_adapter_shared_by_eth_dev(dev);
+	bool valid = rte_atomic_load_explicit(&sas->dev_info_cache_is_valid,
+					      rte_memory_order_acquire);
+
+	if (!valid)
+		return -EAGAIN;
+
+	*dev_info = sas->dev_info_cache;
+
+	/*
+	 * The cache holds stale primary-process pointers; restore
+	 * the process-local values from the caller-supplied 'dev'.
+	 */
+	if (dev_info->switch_info.name != NULL)
+		dev_info->switch_info.name = dev->device->driver->name;
+	dev_info->device = dev->device;
+	return 0;
+}
+
 static const struct eth_dev_ops sfc_eth_dev_secondary_ops = {
+	.dev_infos_get			= sfc_dev_infos_get_secondary,
 	.dev_supported_ptypes_get	= sfc_dev_supported_ptypes_get,
 	.reta_query			= sfc_dev_rss_reta_query,
 	.rss_hash_conf_get		= sfc_dev_rss_hash_conf_get,
@@ -3787,6 +3814,27 @@ static int sfc_eth_dev_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	if (rc != 0)
 		return rc;
 
+	if (dev_created && rte_eal_process_type() == RTE_PROC_PRIMARY) {
+		struct sfc_adapter *sa = sfc_adapter_by_eth_dev(dev);
+		struct sfc_adapter_shared *sas =
+			sfc_adapter_shared_by_eth_dev(dev);
+
+		/*
+		 * Pre-fill the dev info cache for the secondary
+		 * process. The port has been registered at this
+		 * point, allowing use of the public API.
+		 */
+		rc = rte_eth_dev_info_get(dev->data->port_id,
+					  &sas->dev_info_cache);
+		if (rc == 0) {
+			sas->dev_info_cache.device = NULL;
+			rte_atomic_store_explicit(&sas->dev_info_cache_is_valid,
+				true, rte_memory_order_release);
+		} else {
+			sfc_warn(sa, "failed to cache dev info for the secondary process");
+		}
+	}
+
 	rc = sfc_eth_dev_create_representors(dev, &eth_da);
 	if (rc != 0) {
 		if (dev_created)
-- 
2.47.3