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authorVivien Didelot <vivien.didelot@savoirfairelinux.com>2016-09-08 12:50:43 -0400
committerDavid S. Miller <davem@davemloft.net>2016-09-13 11:21:31 -0400
commit308433155a67cb097142292c8943e0aa8d1a1c79 (patch)
treee9334e5218ca665c10cf09bdf67f73e1be5db26a /net/bridge
parent4c73195edbe3a5d7e14ea549bb261cf35c29f0cc (diff)
downloadlinux-308433155a67cb097142292c8943e0aa8d1a1c79.tar.bz2
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 <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge')
-rw-r--r--net/bridge/br_stp_if.c43
1 files changed, 31 insertions, 12 deletions
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);