[dpdk-dev] [PATCH v3] dev: fix virtual dev attach

[Gaetan Rivet]

Checking against error values returned by rte_eal_hotplug_add is
inelegant and prone to mistakes. Additionally, the failed PCI probe
prints a useless error that would throw off unsuspecting users:

   ERROR: failed to parse device "pci:net_ring0"

This error is printed when attempting to probe a virtual device first
with the PCI bus (here, a net_ring0 device), which will inevitably fail.

Use the relevant functions to infer the intended bus. The limitation to
PCI or vdev device is kept for strict API compatibility. Thus the PCI
probe attempt is avoided and the right function is directly called.

Fixes: 1c35f666df07 ("dev: fix attach proceeding with vdev on PCI
success")

Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
---

v2:

  - Avoid the PCI parsing error when attaching a vdev.

v3:

  - Explain the parsing error previously thrown that the current version
    of the patch avoids.

 lib/librte_eal/common/eal_common_dev.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
index d74f978..f98302d 100644
--- a/lib/librte_eal/common/eal_common_dev.c
+++ b/lib/librte_eal/common/eal_common_dev.c
@@ -66,6 +66,7 @@ static int cmp_dev_name(const struct rte_device *dev, const void *_name)
 
 int rte_eal_dev_attach(const char *name, const char *devargs)
 {
+	struct rte_bus *bus;
 	int ret;
 
 	if (name == NULL || devargs == NULL) {
@@ -73,9 +74,18 @@ int rte_eal_dev_attach(const char *name, const char *devargs)
 		return -EINVAL;
 	}
 
-	ret = rte_eal_hotplug_add("pci", name, devargs);
-	if (ret != -EINVAL)
-		return ret;
+	bus = rte_bus_find_by_device_name(name);
+	if (bus == NULL) {
+		RTE_LOG(ERR, EAL, "Unable to find a bus for the device '%s'\n",
+			name);
+		return -EINVAL;
+	}
+	if (strcmp(bus->name, "pci") == 0)
+		return rte_eal_hotplug_add("pci", name, devargs);
+	if (strcmp(bus->name, "vdev") != 0) {
+		RTE_LOG(ERR, EAL, "Device attach is only supported for PCI and vdev devices.\n");
+		return -ENOTSUP;
+	}
 
 	/*
 	 * If we haven't found a bus device the user meant to "hotplug" a
-- 
2.1.4