From 308433155a67cb097142292c8943e0aa8d1a1c79 Mon Sep 17 00:00:00 2001 From: Vivien Didelot Date: Thu, 8 Sep 2016 12:50:43 -0400 Subject: net: bridge: add helper to call /sbin/bridge-stp If /sbin/bridge-stp is available on the system, bridge tries to execute it instead of the kernel implementation when starting/stopping STP. If anything goes wrong with /sbin/bridge-stp, bridge silently falls back to kernel STP, making hard to debug userspace STP. This patch adds a br_stp_call_user helper to start/stop userspace STP and debug errors from the program: abnormal exit status is stored in the lower byte and normal exit status is stored in higher byte. Below is a simple example on a kernel with dynamic debug enabled: # ln -s /bin/false /sbin/bridge-stp # brctl stp br0 on br0: failed to start userspace STP (256) # dmesg br0: /sbin/bridge-stp exited with code 1 br0: failed to start userspace STP (256) br0: using kernel STP Signed-off-by: Vivien Didelot Signed-off-by: David S. Miller --- net/bridge/br_stp_if.c | 43 +++++++++++++++++++++++++++++++------------ 1 file changed, 31 insertions(+), 12 deletions(-) (limited to 'net/bridge/br_stp_if.c') diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c index 341caa0ca63a..d8ad73b38de2 100644 --- a/net/bridge/br_stp_if.c +++ b/net/bridge/br_stp_if.c @@ -134,17 +134,36 @@ void br_stp_disable_port(struct net_bridge_port *p) br_become_root_bridge(br); } -static void br_stp_start(struct net_bridge *br) +static int br_stp_call_user(struct net_bridge *br, char *arg) { - int r; - char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL }; + char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL }; char *envp[] = { NULL }; + int rc; + + /* call userspace STP and report program errors */ + rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC); + if (rc > 0) { + if (rc & 0xff) + br_debug(br, BR_STP_PROG " received signal %d\n", + rc & 0x7f); + else + br_debug(br, BR_STP_PROG " exited with code %d\n", + (rc >> 8) & 0xff); + } + + return rc; +} + +static void br_stp_start(struct net_bridge *br) +{ struct net_bridge_port *p; + int err = -ENOENT; if (net_eq(dev_net(br->dev), &init_net)) - r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC); - else - r = -ENOENT; + err = br_stp_call_user(br, "start"); + + if (err && err != -ENOENT) + br_err(br, "failed to start userspace STP (%d)\n", err); spin_lock_bh(&br->lock); @@ -153,9 +172,10 @@ static void br_stp_start(struct net_bridge *br) else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY) __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY); - if (r == 0) { + if (!err) { br->stp_enabled = BR_USER_STP; br_debug(br, "userspace STP started\n"); + /* Stop hello and hold timers */ del_timer(&br->hello_timer); list_for_each_entry(p, &br->port_list, list) @@ -173,14 +193,13 @@ static void br_stp_start(struct net_bridge *br) static void br_stp_stop(struct net_bridge *br) { - int r; - char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL }; - char *envp[] = { NULL }; struct net_bridge_port *p; + int err; if (br->stp_enabled == BR_USER_STP) { - r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC); - br_info(br, "userspace STP stopped, return code %d\n", r); + err = br_stp_call_user(br, "stop"); + if (err) + br_err(br, "failed to stop userspace STP (%d)\n", err); /* To start timers on any ports left in blocking */ mod_timer(&br->hello_timer, jiffies + br->hello_time); -- cgit v1.2.3