diff mbox series

[v4,net-next,03/18] net: procfs: hold netif_lists_lock when retrieving device statistics

Message ID 20210108002005.3429956-4-olteanv@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Make .ndo_get_stats64 sleepable | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 2 maintainers not CCed: vladimir.oltean@nxp.com pabeni@redhat.com
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

Commit Message

Vladimir Oltean Jan. 8, 2021, 12:19 a.m. UTC 
From: Vladimir Oltean <vladimir.oltean@nxp.com>

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>
---
Changes in v4:
None.

Changes in v3:
None.

Changes in v2:
None.

 net/core/net-procfs.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c
index c714e6a9dad4..4784703c1e39 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);
+
+	netif_lists_lock(net);
+
 	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);
+
+	netif_lists_unlock(net);
 }
 
 static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)