| Message ID | 20201206235919.393158-11-vladimir.oltean@nxp.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Make .ndo_get_stats64 sleepable | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 1 this patch: 1 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 33 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 1 this patch: 1 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c index c714e6a9dad4..83f8a89dfc5a 100644 --- a/net/core/net-procfs.c +++ b/net/core/net-procfs.c @@ -21,7 +21,7 @@ static inline struct net_device *dev_from_same_bucket(struct seq_file *seq, loff unsigned int count = 0, offset = get_offset(*pos); h = &net->dev_index_head[get_bucket(*pos)]; - hlist_for_each_entry_rcu(dev, h, index_hlist) { + hlist_for_each_entry(dev, h, index_hlist) { if (++count == offset) return dev; } @@ -51,9 +51,11 @@ static inline struct net_device *dev_from_bucket(struct seq_file *seq, loff_t *p * in detail. */ static void *dev_seq_start(struct seq_file *seq, loff_t *pos) - __acquires(RCU) { - rcu_read_lock(); + struct net *net = seq_file_net(seq); + + mutex_lock(&net->netdev_lists_lock); + if (!*pos) return SEQ_START_TOKEN; @@ -70,9 +72,10 @@ static void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos) } static void dev_seq_stop(struct seq_file *seq, void *v) - __releases(RCU) { - rcu_read_unlock(); + struct net *net = seq_file_net(seq); + + mutex_unlock(&net->netdev_lists_lock); } static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
In the effort of making .ndo_get_stats64 be able to sleep, we need to ensure the callers of dev_get_stats do not use atomic context. The /proc/net/dev file uses an RCU read-side critical section to ensure the integrity of the list of network interfaces, because it iterates through all net devices in the netns to show their statistics. To offer the equivalent protection against an interface registering or deregistering, while also remaining in sleepable context, we can use the netns mutex for the interface lists. Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- net/core/net-procfs.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)