diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-12-04 20:21:57 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-12-06 16:05:07 -0800 |
| commit | 4d92b95ff2f95f13df9bad0b5a25a9f60e72758d (patch) | |
| tree | 0e0fa4c1662c49b683170ed02da58ab253da23d7 /net | |
| parent | 914a7b5000d08f1487e0efa52f27c4b7ea75b893 (diff) | |
net: add net device refcount tracker infrastructure
net device are refcounted. Over the years we had numerous bugs
caused by imbalanced dev_hold() and dev_put() calls.
The general idea is to be able to precisely pair each decrement with
a corresponding prior increment. Both share a cookie, basically
a pointer to private data storing stack traces.
This patch adds dev_hold_track() and dev_put_track().
To use these helpers, each data structure owning a refcount
should also use a "netdevice_tracker" to pair the hold and put.
netdevice_tracker dev_tracker;
...
dev_hold_track(dev, &dev_tracker, GFP_ATOMIC);
...
dev_put_track(dev, &dev_tracker);
Whenever a leak happens, we will get precise stack traces
of the point dev_hold_track() happened, at device dismantle phase.
We will also get a stack trace if too many dev_put_track() for the same
netdevice_tracker are attempted.
This is guarded by CONFIG_NET_DEV_REFCNT_TRACKER option.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/Kconfig.debug | 10 | ||||
| -rw-r--r-- | net/core/dev.c | 3 |
2 files changed, 13 insertions, 0 deletions
diff --git a/net/Kconfig.debug b/net/Kconfig.debug new file mode 100644 index 000000000000..fb5c70e01cb3 --- /dev/null +++ b/net/Kconfig.debug @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0-only + +config NET_DEV_REFCNT_TRACKER + bool "Enable net device refcount tracking" + depends on DEBUG_KERNEL && STACKTRACE_SUPPORT + select REF_TRACKER + default n + help + Enable debugging feature to track device references. + This adds memory and cpu costs. diff --git a/net/core/dev.c b/net/core/dev.c index aba8acc1238c..1740d6cfe86b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9864,6 +9864,7 @@ static void netdev_wait_allrefs(struct net_device *dev) netdev_unregister_timeout_secs * HZ)) { pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n", dev->name, refcnt); + ref_tracker_dir_print(&dev->refcnt_tracker, 10); warning_time = jiffies; } } @@ -10154,6 +10155,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name, dev = PTR_ALIGN(p, NETDEV_ALIGN); dev->padded = (char *)dev - (char *)p; + ref_tracker_dir_init(&dev->refcnt_tracker, 128); #ifdef CONFIG_PCPU_DEV_REFCNT dev->pcpu_refcnt = alloc_percpu(int); if (!dev->pcpu_refcnt) @@ -10270,6 +10272,7 @@ void free_netdev(struct net_device *dev) list_for_each_entry_safe(p, n, &dev->napi_list, dev_list) netif_napi_del(p); + ref_tracker_dir_exit(&dev->refcnt_tracker); #ifdef CONFIG_PCPU_DEV_REFCNT free_percpu(dev->pcpu_refcnt); dev->pcpu_refcnt = NULL; |