From 5aa3afe107d9099fc0dea2acf82c3e3c8f0f20e2 Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Tue, 23 Mar 2021 07:49:23 +0100 Subject: net: make unregister netdev warning timeout configurable netdev_wait_allrefs() issues a warning if refcount does not drop to 0 after 10 seconds. While 10 second wait generally should not happen under normal workload in normal environment, it seems to fire falsely very often during fuzzing and/or in qemu emulation (~10x slower). At least it's not possible to understand if it's really a false positive or not. Automated testing generally bumps all timeouts to very high values to avoid flake failures. Add net.core.netdev_unregister_timeout_secs sysctl to make the timeout configurable for automated testing systems. Lowering the timeout may also be useful for e.g. manual bisection. The default value matches the current behavior. Signed-off-by: Dmitry Vyukov Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=211877 Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller --- net/core/dev.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index c9a496f5e687..515309573cb8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10322,6 +10322,8 @@ int netdev_refcnt_read(const struct net_device *dev) } EXPORT_SYMBOL(netdev_refcnt_read); +int netdev_unregister_timeout_secs __read_mostly = 10; + #define WAIT_REFS_MIN_MSECS 1 #define WAIT_REFS_MAX_MSECS 250 /** @@ -10383,7 +10385,9 @@ static void netdev_wait_allrefs(struct net_device *dev) refcnt = netdev_refcnt_read(dev); - if (refcnt != 1 && time_after(jiffies, warning_time + 10 * HZ)) { + if (refcnt && + time_after(jiffies, warning_time + + netdev_unregister_timeout_secs * HZ)) { pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n", dev->name, refcnt); warning_time = jiffies; -- cgit