[dpdk-dev] [PATCH v4 4/4] eal: simplify parameters of hotplug functions

[Thomas Monjalon <thomas@monjalon.net>]

All information about a device to probe can be grouped
in a common string, which is what we usually call devargs.
An application should not have to parse this string before
calling the EAL probe function.
And the syntax could evolve to be more complex and support
matching multiple devices in one string.
That's why the bus name and device name should be removed from
rte_eal_hotplug_add().
Instead of changing this function, a simpler one is added
and used in the old one, which may be deprecated later.

When removing a device, we already know its rte_device handle
which can be directly passed as parameter of rte_eal_hotplug_remove().
If the rte_device is not known, it can be retrieved with the devargs,
by iterating in the device list (future RTE_DEV_FOREACH()).
Similarly to the probing case, a new function is added
and used in the old one, which may be deprecated later.
The new function is used in failsafe, because the replacement is easy.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
---
 drivers/net/failsafe/failsafe_eal.c     |  3 +-
 drivers/net/failsafe/failsafe_ether.c   |  3 +-
 lib/librte_eal/common/eal_common_dev.c  | 80 ++++++++++++++++---------
 lib/librte_eal/common/include/rte_dev.h | 30 +++++++++-
 lib/librte_eal/rte_eal_version.map      |  2 +
 5 files changed, 84 insertions(+), 34 deletions(-)

diff --git a/drivers/net/failsafe/failsafe_eal.c b/drivers/net/failsafe/failsafe_eal.c
index ce1633f13..8a888b1ff 100644
--- a/drivers/net/failsafe/failsafe_eal.c
+++ b/drivers/net/failsafe/failsafe_eal.c
@@ -144,8 +144,7 @@ fs_bus_uninit(struct rte_eth_dev *dev)
 	int ret = 0;
 
 	FOREACH_SUBDEV_STATE(sdev, i, dev, DEV_PROBED) {
-		sdev_ret = rte_eal_hotplug_remove(sdev->bus->name,
-							sdev->dev->name);
+		sdev_ret = rte_dev_remove(sdev->dev);
 		if (sdev_ret) {
 			ERROR("Failed to remove requested device %s (err: %d)",
 			      sdev->dev->name, sdev_ret);
diff --git a/drivers/net/failsafe/failsafe_ether.c b/drivers/net/failsafe/failsafe_ether.c
index 51c96f78b..f2512c430 100644
--- a/drivers/net/failsafe/failsafe_ether.c
+++ b/drivers/net/failsafe/failsafe_ether.c
@@ -282,8 +282,7 @@ fs_dev_remove(struct sub_device *sdev)
 		sdev->state = DEV_PROBED;
 		/* fallthrough */
 	case DEV_PROBED:
-		ret = rte_eal_hotplug_remove(sdev->bus->name,
-					     sdev->dev->name);
+		ret = rte_dev_remove(sdev->dev);
 		if (ret) {
 			ERROR("Bus detach failed for sub_device %u",
 			      SUB_ID(sdev));
diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
index a9be58edf..713707b9a 100644
--- a/lib/librte_eal/common/eal_common_dev.c
+++ b/lib/librte_eal/common/eal_common_dev.c
@@ -129,46 +129,61 @@ int rte_eal_dev_detach(struct rte_device *dev)
 
 int
 rte_eal_hotplug_add(const char *busname, const char *devname,
-		    const char *devargs)
+		    const char *drvargs)
 {
-	struct rte_bus *bus;
-	struct rte_device *dev;
-	struct rte_devargs *da;
 	int ret;
+	char *devargs = NULL;
+	int size, length = -1;
 
-	bus = rte_bus_find_by_name(busname);
-	if (bus == NULL) {
-		RTE_LOG(ERR, EAL, "Cannot find bus (%s)\n", busname);
-		return -ENOENT;
-	}
+	do { /* 2 iterations: first is to know string length */
+		size = length + 1;
+		length = snprintf(devargs, size, "%s:%s,%s", busname, devname, drvargs);
+		if (length >= size)
+			devargs = malloc(length + 1);
+		if (devargs == NULL)
+			return -ENOMEM;
+	} while (size == 0);
 
-	if (bus->plug == NULL) {
-		RTE_LOG(ERR, EAL, "Function plug not supported by bus (%s)\n",
-			bus->name);
-		return -ENOTSUP;
-	}
+	ret = rte_dev_probe(devargs);
+
+	free(devargs);
+	return ret;
+}
+
+int __rte_experimental
+rte_dev_probe(const char *devargs)
+{
+	struct rte_device *dev;
+	struct rte_devargs *da;
+	int ret;
 
 	da = calloc(1, sizeof(*da));
 	if (da == NULL)
 		return -ENOMEM;
 
-	ret = rte_devargs_parsef(da, "%s:%s,%s",
-				 busname, devname, devargs);
+	ret = rte_devargs_parse(da, devargs);
 	if (ret)
 		goto err_devarg;
 
+	if (da->bus->plug == NULL) {
+		RTE_LOG(ERR, EAL, "Function plug not supported by bus (%s)\n",
+			da->bus->name);
+		ret = -ENOTSUP;
+		goto err_devarg;
+	}
+
 	ret = rte_devargs_insert(da);
 	if (ret)
 		goto err_devarg;
 
-	ret = bus->scan();
+	ret = da->bus->scan();
 	if (ret)
 		goto err_devarg;
 
-	dev = bus->find_device(NULL, cmp_dev_name, devname);
+	dev = da->bus->find_device(NULL, cmp_dev_name, da->name);
 	if (dev == NULL) {
 		RTE_LOG(ERR, EAL, "Cannot find device (%s)\n",
-			devname);
+			da->name);
 		ret = -ENODEV;
 		goto err_devarg;
 	}
@@ -178,7 +193,7 @@ rte_eal_hotplug_add(const char *busname, const char *devname,
 		return -EEXIST;
 	}
 
-	ret = bus->plug(dev);
+	ret = da->bus->plug(dev);
 	if (ret) {
 		RTE_LOG(ERR, EAL, "Driver cannot attach the device (%s)\n",
 			dev->name);
@@ -197,9 +212,8 @@ rte_eal_hotplug_add(const char *busname, const char *devname,
 int
 rte_eal_hotplug_remove(const char *busname, const char *devname)
 {
-	struct rte_bus *bus;
 	struct rte_device *dev;
-	int ret;
+	struct rte_bus *bus;
 
 	bus = rte_bus_find_by_name(busname);
 	if (bus == NULL) {
@@ -207,23 +221,33 @@ rte_eal_hotplug_remove(const char *busname, const char *devname)
 		return -ENOENT;
 	}
 
-	if (bus->unplug == NULL) {
-		RTE_LOG(ERR, EAL, "Function unplug not supported by bus (%s)\n",
-			bus->name);
-		return -ENOTSUP;
-	}
-
 	dev = bus->find_device(NULL, cmp_dev_name, devname);
 	if (dev == NULL) {
 		RTE_LOG(ERR, EAL, "Cannot find plugged device (%s)\n", devname);
 		return -EINVAL;
 	}
 
+	return rte_dev_remove(dev);
+}
+
+int __rte_experimental
+rte_dev_remove(struct rte_device *dev)
+{
+	struct rte_bus *bus;
+	int ret;
+
 	if (dev->driver == NULL) {
 		RTE_LOG(ERR, EAL, "Device is already unplugged\n");
 		return -ENOENT;
 	}
 
+	bus = dev->devargs->bus;
+	if (bus->unplug == NULL) {
+		RTE_LOG(ERR, EAL, "Function unplug not supported by bus (%s)\n",
+			bus->name);
+		return -ENOTSUP;
+	}
+
 	ret = bus->unplug(dev);
 	if (ret)
 		RTE_LOG(ERR, EAL, "Driver cannot detach the device (%s)\n",
diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
index d440c4e58..ee77e4006 100644
--- a/lib/librte_eal/common/include/rte_dev.h
+++ b/lib/librte_eal/common/include/rte_dev.h
@@ -196,13 +196,26 @@ int rte_eal_dev_detach(struct rte_device *dev);
  * @param devname
  *   The device name. Based on this device name, eal will identify a driver
  *   capable of handling it and pass it to the driver probing function.
- * @param devargs
+ * @param drvargs
  *   Device arguments to be passed to the driver.
  * @return
  *   0 on success, negative on error.
  */
 int rte_eal_hotplug_add(const char *busname, const char *devname,
-			const char *devargs);
+			const char *drvargs);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Add matching devices.
+ *
+ * @param devargs
+ *   Device arguments including bus, class and driver properties.
+ * @return
+ *   0 on success, negative on error.
+ */
+int __rte_experimental rte_dev_probe(const char *devargs);
 
 /**
  * Hotplug remove a given device from a specific bus.
@@ -216,6 +229,19 @@ int rte_eal_hotplug_add(const char *busname, const char *devname,
  */
 int rte_eal_hotplug_remove(const char *busname, const char *devname);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Remove one device.
+ *
+ * @param dev
+ *   Data structure of the device to remove.
+ * @return
+ *   0 on success, negative on error.
+ */
+int __rte_experimental rte_dev_remove(struct rte_device *dev);
+
 /**
  * Device comparison function.
  *
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 6bff37f4b..2ea7a870a 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -281,6 +281,8 @@ EXPERIMENTAL {
 	rte_dev_event_monitor_stop;
 	rte_dev_iterator_init;
 	rte_dev_iterator_next;
+	rte_dev_probe;
+	rte_dev_remove;
 	rte_devargs_add;
 	rte_devargs_dump;
 	rte_devargs_insert;
-- 
2.19.0