[dpdk-dev] [PATCH v20.11 2/2] eal: improve device probing API

[Maxime Coquelin]

This patch makes rte_dev_probe() to return the
rte_device pointer on success and NULL on error
instead of returning 0 on success and negative
value on error.

The goal is to avoid that the calling application
iterates the devices list afterwards to retrieve
the pointer. Retrieving the pointer is required
for calling rte_dev_remove() later.

Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 app/test-pmd/testpmd.c                 |  2 +-
 drivers/net/failsafe/failsafe.c        |  5 +++--
 lib/librte_eal/common/eal_common_dev.c | 18 ++++++++++--------
 lib/librte_eal/include/rte_dev.h       |  4 ++--
 4 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index 4989d22ca8..f777f449a8 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -2764,7 +2764,7 @@ attach_port(char *identifier)
 		return;
 	}
 
-	if (rte_dev_probe(identifier) < 0) {
+	if (rte_dev_probe(identifier) == NULL) {
 		TESTPMD_LOG(ERR, "Failed to attach port %s\n", identifier);
 		return;
 	}
diff --git a/drivers/net/failsafe/failsafe.c b/drivers/net/failsafe/failsafe.c
index 72362f35de..e32effdef2 100644
--- a/drivers/net/failsafe/failsafe.c
+++ b/drivers/net/failsafe/failsafe.c
@@ -341,6 +341,7 @@ rte_pmd_failsafe_probe(struct rte_vdev_device *vdev)
 	struct rte_eth_dev *eth_dev;
 	struct sub_device  *sdev;
 	struct rte_devargs devargs;
+	struct rte_device *dev;
 	uint8_t i;
 	int ret;
 
@@ -378,8 +379,8 @@ rte_pmd_failsafe_probe(struct rte_vdev_device *vdev)
 				continue;
 			}
 			if (!devargs_already_listed(&devargs)) {
-				ret = rte_dev_probe(devargs.name);
-				if (ret < 0) {
+				dev = rte_dev_probe(devargs.name);
+				if (dev == NULL) {
 					ERROR("Failed to probe devargs %s",
 					      devargs.name);
 					continue;
diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
index 9e4f09d83e..72baae2e48 100644
--- a/lib/librte_eal/common/eal_common_dev.c
+++ b/lib/librte_eal/common/eal_common_dev.c
@@ -120,7 +120,9 @@ rte_eal_hotplug_add(const char *busname, const char *devname,
 	if (ret != 0)
 		return ret;
 
-	ret = rte_dev_probe(devargs);
+	if (rte_dev_probe(devargs) == NULL)
+		ret = -1;
+
 	free(devargs);
 
 	return ret;
@@ -192,7 +194,7 @@ local_dev_probe(const char *devargs, struct rte_device **new_dev)
 	return ret;
 }
 
-int
+struct rte_device *
 rte_dev_probe(const char *devargs)
 {
 	struct eal_dev_mp_req req;
@@ -212,12 +214,12 @@ rte_dev_probe(const char *devargs)
 		if (ret != 0) {
 			RTE_LOG(ERR, EAL,
 				"Failed to send hotplug request to primary\n");
-			return -ENOMSG;
+			return NULL;
 		}
 		if (req.result != 0)
 			RTE_LOG(ERR, EAL,
 				"Failed to hotplug add device\n");
-		return req.result;
+		return NULL;
 	}
 
 	/* attach a shared device from primary start from here: */
@@ -236,7 +238,7 @@ rte_dev_probe(const char *devargs)
 		 * process.
 		 */
 		if (ret != -EEXIST)
-			return ret;
+			return dev;
 	}
 
 	/* primary send attach sync request to secondary. */
@@ -261,11 +263,11 @@ rte_dev_probe(const char *devargs)
 
 		/* for -EEXIST, we don't need to rollback. */
 		if (ret == -EEXIST)
-			return ret;
+			return dev;
 		goto rollback;
 	}
 
-	return 0;
+	return dev;
 
 rollback:
 	req.t = EAL_DEV_REQ_TYPE_ATTACH_ROLLBACK;
@@ -282,7 +284,7 @@ rte_dev_probe(const char *devargs)
 			"Failed to rollback device attach on primary."
 			"Devices in secondary may not sync with primary\n");
 
-	return ret;
+	return NULL;
 }
 
 int
diff --git a/lib/librte_eal/include/rte_dev.h b/lib/librte_eal/include/rte_dev.h
index c8d985fb5c..9cf7c7fd71 100644
--- a/lib/librte_eal/include/rte_dev.h
+++ b/lib/librte_eal/include/rte_dev.h
@@ -148,9 +148,9 @@ int rte_eal_hotplug_add(const char *busname, const char *devname,
  * @param devargs
  *   Device arguments including bus, class and driver properties.
  * @return
- *   0 on success, negative on error.
+ *   Generic device pointer on success, NULL on error.
  */
-int rte_dev_probe(const char *devargs);
+struct rte_device *rte_dev_probe(const char *devargs);
 
 /**
  * Hotplug remove a given device from a specific bus.
-- 
2.26.2