[dpdk-stable] patch 'net/tap: let kernel choose tun device name' has been queued to LTS release 18.11.1

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/07/19. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Thanks.

Kevin Traynor

---
>From d3034e04e58ca7bed78182fa9a1439afe4a73d4b Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <stephen at networkplumber.org>
Date: Fri, 11 Jan 2019 12:35:18 -0800
Subject: [PATCH] net/tap: let kernel choose tun device name

[ upstream commit b5235d61f3b7d2b1c2b9ee2601f3aca2b151b508 ]

Assigning tun and tap index in DPDK tap device driver is racy
and fails if used with primary/secondary. Instead use the kernel
feature of device wildcarding where if a name with %d is used
the kernel will fill in the next available device.

Fixes: 02f96a0a82d1 ("net/tap: add TUN/TAP device PMD")

Reported-by: Haifeng Li <hfli at netitest.com>
Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
Acked-by Keith Wiles <keith.wiles at intel.com>
---
 drivers/net/tap/rte_eth_tap.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index aef8b0b9f..a93429973 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -79,7 +79,4 @@ static const char *valid_arguments[] = {
 };
 
-static unsigned int tap_unit;
-static unsigned int tun_unit;
-
 static char tuntap_name[8];
 
@@ -151,6 +148,4 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
 	snprintf(ifr.ifr_name, IFNAMSIZ, "%s", pmd->name);
 
-	TAP_LOG(DEBUG, "ifr_name '%s'", ifr.ifr_name);
-
 	fd = open(TUN_TAP_DEV_PATH, O_RDWR);
 	if (fd < 0) {
@@ -186,4 +181,11 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
 	}
 
+	/*
+	 * Name passed to kernel might be wildcard like dtun%d
+	 * and need to find the resulting device.
+	 */
+	TAP_LOG(DEBUG, "Device name is '%s'", ifr.ifr_name);
+	strlcpy(pmd->name, ifr.ifr_name, RTE_ETH_NAME_MAX_LEN);
+
 	if (is_keepalive) {
 		/*
@@ -1756,4 +1758,5 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
 		goto error_exit;
 	}
+	TAP_LOG(DEBUG, "allocated %s", pmd->name);
 
 	ifr.ifr_mtu = dev->data->mtu;
@@ -1895,6 +1898,6 @@ set_interface_name(const char *key __rte_unused,
 		strlcpy(name, value, RTE_ETH_NAME_MAX_LEN);
 	else
-		snprintf(name, RTE_ETH_NAME_MAX_LEN, "%s%d",
-			 DEFAULT_TAP_NAME, tap_unit - 1);
+		/* use tap%d which causes kernel to choose next available */
+		strlcpy(name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN);
 
 	return 0;
@@ -2003,6 +2006,6 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
 	}
 
-	snprintf(tun_name, sizeof(tun_name), "%s%u",
-		 DEFAULT_TUN_NAME, tun_unit++);
+	/* use tun%d which causes kernel to choose next available */
+	strlcpy(tun_name, DEFAULT_TUN_NAME "%d", RTE_ETH_NAME_MAX_LEN);
 
 	if (params && (params[0] != '\0')) {
@@ -2024,9 +2027,8 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
 	pmd_link.link_speed = ETH_SPEED_NUM_10G;
 
-	TAP_LOG(NOTICE, "Initializing pmd_tun for %s as %s",
-		name, tun_name);
+	TAP_LOG(NOTICE, "Initializing pmd_tun for %s", name);
 
 	ret = eth_dev_tap_create(dev, tun_name, remote_iface, 0,
-		ETH_TUNTAP_TYPE_TUN);
+				 ETH_TUNTAP_TYPE_TUN);
 
 leave:
@@ -2034,5 +2036,4 @@ leave:
 		TAP_LOG(ERR, "Failed to create pmd for %s as %s",
 			name, tun_name);
-		tun_unit--; /* Restore the unit number */
 	}
 	rte_kvargs_free(kvlist);
@@ -2190,6 +2191,7 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev)
 
 	speed = ETH_SPEED_NUM_10G;
-	snprintf(tap_name, sizeof(tap_name), "%s%u",
-		 DEFAULT_TAP_NAME, tap_unit++);
+
+	/* use tap%d which causes kernel to choose next available */
+	strlcpy(tap_name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN);
 	memset(remote_iface, 0, RTE_ETH_NAME_MAX_LEN);
 
@@ -2255,5 +2257,4 @@ leave:
 			tap_devices_count--;
 		}
-		tap_unit--;		/* Restore the unit number */
 	}
 	rte_kvargs_free(kvlist);
-- 
2.19.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2019-01-31 15:44:06.948575581 +0000
+++ 0052-net-tap-let-kernel-choose-tun-device-name.patch	2019-01-31 15:44:05.000000000 +0000
@@ -1,15 +1,16 @@
-From b5235d61f3b7d2b1c2b9ee2601f3aca2b151b508 Mon Sep 17 00:00:00 2001
+From d3034e04e58ca7bed78182fa9a1439afe4a73d4b Mon Sep 17 00:00:00 2001
 From: Stephen Hemminger <stephen at networkplumber.org>
 Date: Fri, 11 Jan 2019 12:35:18 -0800
 Subject: [PATCH] net/tap: let kernel choose tun device name
 
+[ upstream commit b5235d61f3b7d2b1c2b9ee2601f3aca2b151b508 ]
+
 Assigning tun and tap index in DPDK tap device driver is racy
 and fails if used with primary/secondary. Instead use the kernel
 feature of device wildcarding where if a name with %d is used
 the kernel will fill in the next available device.
 
 Fixes: 02f96a0a82d1 ("net/tap: add TUN/TAP device PMD")
-Cc: stable at dpdk.org
 
 Reported-by: Haifeng Li <hfli at netitest.com>
 Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
@@ -19,10 +20,10 @@
  1 file changed, 17 insertions(+), 16 deletions(-)
 
 diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
-index d699b4fb0..ed8483cb9 100644
+index aef8b0b9f..a93429973 100644
 --- a/drivers/net/tap/rte_eth_tap.c
 +++ b/drivers/net/tap/rte_eth_tap.c
-@@ -80,7 +80,4 @@ static const char *valid_arguments[] = {
+@@ -79,7 +79,4 @@ static const char *valid_arguments[] = {
  };
  
 -static unsigned int tap_unit;
@@ -30,14 +31,14 @@
 -
  static char tuntap_name[8];
  
-@@ -152,6 +149,4 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
- 	strlcpy(ifr.ifr_name, pmd->name, IFNAMSIZ);
+@@ -151,6 +148,4 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
+ 	snprintf(ifr.ifr_name, IFNAMSIZ, "%s", pmd->name);
  
 -	TAP_LOG(DEBUG, "ifr_name '%s'", ifr.ifr_name);
 -
  	fd = open(TUN_TAP_DEV_PATH, O_RDWR);
  	if (fd < 0) {
-@@ -187,4 +182,11 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
+@@ -186,4 +181,11 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive)
  	}
  
 +	/*
@@ -49,22 +50,22 @@
 +
  	if (is_keepalive) {
  		/*
-@@ -1757,4 +1759,5 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
+@@ -1756,4 +1758,5 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name,
  		goto error_exit;
  	}
 +	TAP_LOG(DEBUG, "allocated %s", pmd->name);
  
  	ifr.ifr_mtu = dev->data->mtu;
-@@ -1919,6 +1922,6 @@ set_interface_name(const char *key __rte_unused,
+@@ -1895,6 +1898,6 @@ set_interface_name(const char *key __rte_unused,
  		strlcpy(name, value, RTE_ETH_NAME_MAX_LEN);
- 	} else {
+ 	else
 -		snprintf(name, RTE_ETH_NAME_MAX_LEN, "%s%d",
 -			 DEFAULT_TAP_NAME, tap_unit - 1);
 +		/* use tap%d which causes kernel to choose next available */
 +		strlcpy(name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN);
- 	}
+ 
  	return 0;
-@@ -2033,6 +2036,6 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
+@@ -2003,6 +2006,6 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
  	}
  
 -	snprintf(tun_name, sizeof(tun_name), "%s%u",
@@ -73,25 +74,25 @@
 +	strlcpy(tun_name, DEFAULT_TUN_NAME "%d", RTE_ETH_NAME_MAX_LEN);
  
  	if (params && (params[0] != '\0')) {
-@@ -2054,9 +2057,8 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
+@@ -2024,9 +2027,8 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev)
  	pmd_link.link_speed = ETH_SPEED_NUM_10G;
  
--	TAP_LOG(DEBUG, "Initializing pmd_tun for %s as %s",
+-	TAP_LOG(NOTICE, "Initializing pmd_tun for %s as %s",
 -		name, tun_name);
-+	TAP_LOG(DEBUG, "Initializing pmd_tun for %s", name);
++	TAP_LOG(NOTICE, "Initializing pmd_tun for %s", name);
  
  	ret = eth_dev_tap_create(dev, tun_name, remote_iface, 0,
 -		ETH_TUNTAP_TYPE_TUN);
 +				 ETH_TUNTAP_TYPE_TUN);
  
  leave:
-@@ -2064,5 +2066,4 @@ leave:
+@@ -2034,5 +2036,4 @@ leave:
  		TAP_LOG(ERR, "Failed to create pmd for %s as %s",
  			name, tun_name);
 -		tun_unit--; /* Restore the unit number */
  	}
  	rte_kvargs_free(kvlist);
-@@ -2220,6 +2221,7 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev)
+@@ -2190,6 +2191,7 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev)
  
  	speed = ETH_SPEED_NUM_10G;
 -	snprintf(tap_name, sizeof(tap_name), "%s%u",
@@ -101,7 +102,7 @@
 +	strlcpy(tap_name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN);
  	memset(remote_iface, 0, RTE_ETH_NAME_MAX_LEN);
  
-@@ -2284,5 +2286,4 @@ leave:
+@@ -2255,5 +2257,4 @@ leave:
  			tap_devices_count--;
  		}
 -		tap_unit--;		/* Restore the unit number */