[dpdk-dev] [PATCH v2 08/13] net/failsafe: add flexible device definition

[Gaetan Rivet]

Add the "exec" device type.
The parameters given to this type of device will be executed in a shell.
The output of this command is then used as a definition for a device.

That command can be re-interpreted if the related device is not
plugged-in. It allows for a device definition to react to system
changes (e.g. changing PCI bus for a given device).

Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
Acked-by: Olga Shern <olgas at mellanox.com>
---
 doc/guides/nics/fail_safe.rst           |  16 +++++
 drivers/net/failsafe/failsafe_args.c    | 102 ++++++++++++++++++++++++++++++++
 drivers/net/failsafe/failsafe_ether.c   |   7 +++
 drivers/net/failsafe/failsafe_private.h |   4 ++
 4 files changed, 129 insertions(+)

diff --git a/doc/guides/nics/fail_safe.rst b/doc/guides/nics/fail_safe.rst
index 74bd807..bb8a221 100644
--- a/doc/guides/nics/fail_safe.rst
+++ b/doc/guides/nics/fail_safe.rst
@@ -91,6 +91,15 @@ Fail-safe command line parameters
   additional sub-device parameters if need be. They will be passed on to the
   sub-device.
 
+- **exec(<shell command>)** parameter
+
+  This parameter allows the user to provide a command to the fail-safe PMD to
+  execute and define a sub-device. It is done within a regular shell context.
+  The first line of its output is read by the fail-safe PMD and otherwise
+  interpreted as if passed by the regular **dev** parameter. Any other line is
+  discarded. If the command fail or output an incorrect string, the sub-device
+  is not initialized.
+
 - **mac** parameter [MAC address]
 
   This parameter allows the user to set a default MAC address to the fail-safe
@@ -126,6 +135,13 @@ This section shows some example of using **testpmd** with a fail-safe PMD.
          --vdev='net_failsafe0,mac=de:ad:be:ef:01:02,dev(84:00.0),dev(net_ring0,nodeaction=r1:0:CREATE)' -- \
          -i
 
+#. Start testpmd using a flexible device definition
+
+   .. code-block:: console
+
+      $RTE_TARGET/build/app/testpmd -c 0xff -n 4 --no-pci \
+         --vdev='net_failsafe0,exec(echo 84:00.0)' -- -i
+
 Using the Fail-safe PMD from an application
 -------------------------------------------
 
diff --git a/drivers/net/failsafe/failsafe_args.c b/drivers/net/failsafe/failsafe_args.c
index 773b322..839831f 100644
--- a/drivers/net/failsafe/failsafe_args.c
+++ b/drivers/net/failsafe/failsafe_args.c
@@ -112,6 +112,80 @@ parse_device(struct sub_device *sdev, char *args)
 	return 0;
 }
 
+static void
+sanitize_cmdline(char *args)
+{
+	size_t len;
+
+	len = strnlen(args, DEVARGS_MAXLEN);
+	args[len - 1] = '\0';
+}
+
+static int
+execute_cmd(struct sub_device *sdev, char *cmdline)
+{
+	FILE *fp;
+	/* store possible newline as well */
+	char output[DEVARGS_MAXLEN + 1];
+	size_t len;
+	int old_err;
+	int ret;
+
+	DEBUG("'%s'", cmdline);
+	if (cmdline == NULL &&
+	    sdev->cmdline == NULL) {
+		/* debug: should never happen to a user */
+		DEBUG("Invalid command line");
+		return -EINVAL;
+	}
+	if (sdev->cmdline == NULL) {
+		char *new_str;
+
+		len = strlen(cmdline) + 1;
+		new_str = rte_realloc(sdev->cmdline, len,
+				RTE_CACHE_LINE_SIZE);
+		if (new_str == NULL) {
+			ERROR("Command line allocation failed");
+			return -ENOMEM;
+		}
+		sdev->cmdline = new_str;
+		snprintf(sdev->cmdline, len, "%s", cmdline);
+	} else {
+		if (strcmp(sdev->cmdline, cmdline))
+			DEBUG("cmd mismatch: '%s' != '%s'",
+				sdev->cmdline, cmdline);
+		cmdline = sdev->cmdline;
+	}
+	old_err = errno;
+	fp = popen(cmdline, "r");
+	if (fp == NULL) {
+		ret = errno;
+		ERROR("popen: %s", strerror(errno));
+		errno = old_err;
+		return ret;
+	}
+	/* We only read one line */
+	if (fgets(output, sizeof(output) - 1, fp) == NULL) {
+		DEBUG("Could not read command output");
+		return -ENODEV;
+	}
+	sanitize_cmdline(output);
+	ret = parse_device(sdev, output);
+	if (ret) {
+		ERROR("Parsing device '%s' failed", output);
+		goto ret_pclose;
+	}
+ret_pclose:
+	ret = pclose(fp);
+	if (ret) {
+		ret = errno;
+		ERROR("pclose: %s", strerror(errno));
+		errno = old_err;
+		return ret;
+	}
+	return ret;
+}
+
 static int
 parse_device_param(struct rte_eth_dev *dev, const char *param,
 		uint8_t head)
@@ -146,6 +220,14 @@ parse_device_param(struct rte_eth_dev *dev, const char *param,
 		ret = parse_device(sdev, args);
 		if (ret)
 			goto free_args;
+	} else if (strncmp(param, "exec", 4) == 0) {
+		ret = execute_cmd(sdev, args);
+		if (ret == -ENODEV) {
+			DEBUG("Reading device info from command line failed");
+			ret = 0;
+		}
+		if (ret)
+			goto free_args;
 	} else {
 		ERROR("Unrecognized device type: %.*s", (int)b, param);
 		return -EINVAL;
@@ -347,6 +429,8 @@ failsafe_args_free(struct rte_eth_dev *dev)
 	uint8_t i;
 
 	FOREACH_SUBDEV(sdev, i, dev) {
+		rte_free(sdev->cmdline);
+		sdev->cmdline = NULL;
 		free(sdev->devargs.args);
 		sdev->devargs.args = NULL;
 	}
@@ -377,3 +461,21 @@ failsafe_args_count_subdevice(struct rte_eth_dev *dev,
 	return parse_sub_devices(count_device,
 				dev, params);
 }
+
+int
+failsafe_args_parse_subs(struct rte_eth_dev *dev)
+{
+	struct sub_device *sdev;
+	uint8_t i;
+	int ret = 0;
+
+	FOREACH_SUBDEV(sdev, i, dev) {
+		if (sdev->state >= DEV_PARSED)
+			continue;
+		if (sdev->cmdline)
+			ret = execute_cmd(sdev, sdev->cmdline);
+		if (ret == 0)
+			sdev->state = DEV_PARSED;
+	}
+	return 0;
+}
diff --git a/drivers/net/failsafe/failsafe_ether.c b/drivers/net/failsafe/failsafe_ether.c
index ccdd471..a6ccf8f 100644
--- a/drivers/net/failsafe/failsafe_ether.c
+++ b/drivers/net/failsafe/failsafe_ether.c
@@ -188,6 +188,13 @@ failsafe_eth_dev_state_sync(struct rte_eth_dev *dev)
 	int ret;
 	uint8_t i;
 
+	if (PRIV(dev)->state < DEV_PARSED)
+		return 0;
+
+	ret = failsafe_args_parse_subs(dev);
+	if (ret)
+		return ret;
+
 	if (PRIV(dev)->state < DEV_PROBED)
 		return 0;
 	ret = failsafe_eal_init(dev);
diff --git a/drivers/net/failsafe/failsafe_private.h b/drivers/net/failsafe/failsafe_private.h
index bb27223..fcd5b75 100644
--- a/drivers/net/failsafe/failsafe_private.h
+++ b/drivers/net/failsafe/failsafe_private.h
@@ -45,6 +45,7 @@
 #define PMD_FAILSAFE_PLUG_IN_POLL_KVARG "plug_in_poll"
 #define PMD_FAILSAFE_PARAM_STRING	\
 	"dev(<ifc>),"			\
+	"exec(<shell command>),"	\
 	"mac=mac_addr,"			\
 	"plug_in_poll=u64"		\
 	""
@@ -92,6 +93,8 @@ struct sub_device {
 	struct rte_eth_dev *eth_dev;
 	/* Device state machine */
 	enum dev_state state;
+	/* Some device are defined as a command line */
+	char *cmdline;
 };
 
 struct fs_priv {
@@ -140,6 +143,7 @@ uint16_t failsafe_tx_burst(void *txq,
 int failsafe_args_parse(struct rte_eth_dev *dev, const char *params);
 void failsafe_args_free(struct rte_eth_dev *dev);
 int failsafe_args_count_subdevice(struct rte_eth_dev *dev, const char *params);
+int failsafe_args_parse_subs(struct rte_eth_dev *dev);
 
 /* EAL */
 
-- 
2.1.4