[PATCH net-next v2] net: change netdev_unregister_timeout_secs min value to 1

Dmitry Vyukov
2021-03-25T14:53:47Z

netdev_unregister_timeout_secs=0 can lead to printing the
"waiting for dev to become free" message every jiffy.
This is too frequent and unnecessary.
Set the min value to 1 second.

Also fix the merge issue introduced by
"net: make unregister netdev warning timeout configurable":
it changed "refcnt != 1" to "refcnt".

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Fixes: 5aa3afe107d9 ("net: make unregister netdev warning timeout configurable")
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes since v1:
- fix merge issue related to refcnt check
---
Documentation/admin-guide/sysctl/net.rst | 2 +-
net/core/dev.c | 2 +-
net/core/sysctl_net_core.c | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index 2090bfc69aa50..c941b214e0b7f 100644
--- a/Documentation/admin-guide/sysctl/net.rst
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -320,7 +320,7 @@ waiting for a network device refcount to drop to 0 during device
unregistration. A lower value may be useful during bisection to detect
a leaked reference faster. A larger value may be useful to prevent false
warnings on slow/loaded systems.
-Default value is 10, minimum 0, maximum 3600.
+Default value is 10, minimum 1, maximum 3600.

optmem_max
----------
diff --git a/net/core/dev.c b/net/core/dev.c
index 4bb6dcdbed8b8..7bb00b8b86c64 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10431,7 +10431,7 @@ static void netdev_wait_allrefs(struct net_device *dev)

refcnt = netdev_refcnt_read(dev);

- if (refcnt &&
+ if (refcnt != 1 &&
time_after(jiffies, warning_time +
netdev_unregister_timeout_secs * HZ)) {
pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index d84c8a1b280e2..c8496c1142c9d 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -577,7 +577,7 @@ static struct ctl_table net_core_table[] = {
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
+ .extra1 = SYSCTL_ONE,
.extra2 = &int_3600,
},
{ }

base-commit: 84c7f6c33f42a12eb036ebf0f0e3670799304120
--
2.31.0.291.g576ba9dcdaf-goog