net: fix /proc/net/dev regression

Commit f04565ddf52 (dev: use name hash for dev_seq_ops) added a second
regression, as some devices are missing from /proc/net/dev if many
devices are defined.

When seq_file buffer is filled, the last ->next/show() method is
canceled (pos value is reverted to value prior ->next() call)

Problem is after above commit, we dont restart the lookup at right
position in ->start() method.

Fix this by removing the internal 'pos' pointer added in commit, since
we need to use the 'loff_t *pos' provided by seq_file layer.

This also reverts commit 5cac98dd0 (net: Fix corruption
in /proc/*/net/dev_mcast), since its not needed anymore.

Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Mihai Maruseac <mmaruseac@ixiacom.com>
Tested-by:  Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 15 insertions, 48 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1f77540bdc95..5cbaa20f1659 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2604,8 +2604,6 @@ extern void		net_disable_timestamp(void);
 extern void *dev_seq_start(struct seq_file *seq, loff_t *pos);
 extern void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos);
 extern void dev_seq_stop(struct seq_file *seq, void *v);
-extern int dev_seq_open_ops(struct inode *inode, struct file *file,
-                            const struct seq_operations *ops);
 #endif
 
 extern int netdev_class_create_file(struct class_attribute *class_attr);
diff --git a/net/core/dev.c b/net/core/dev.c
index 6c7dc9d78e10..c25d453b2803 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4028,54 +4028,41 @@ static int dev_ifconf(struct net *net, char __user *arg)
 
 #ifdef CONFIG_PROC_FS
 
-#define BUCKET_SPACE (32 - NETDEV_HASHBITS)
-
-struct dev_iter_state {
-        struct seq_net_private p;
-        unsigned int pos; /* bucket << BUCKET_SPACE + offset */
-};
+#define BUCKET_SPACE (32 - NETDEV_HASHBITS - 1)
 
 #define get_bucket(x) ((x) >> BUCKET_SPACE)
 #define get_offset(x) ((x) & ((1 << BUCKET_SPACE) - 1))
 #define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
 
-static inline struct net_device *dev_from_same_bucket(struct seq_file *seq)
+static inline struct net_device *dev_from_same_bucket(struct seq_file *seq, loff_t *pos)
 {
-        struct dev_iter_state *state = seq->private;
         struct net *net = seq_file_net(seq);
         struct net_device *dev;
         struct hlist_node *p;
         struct hlist_head *h;
-        unsigned int count, bucket, offset;
+        unsigned int count = 0, offset = get_offset(*pos);
 
-        bucket = get_bucket(state->pos);
-        offset = get_offset(state->pos);
-        h = &net->dev_name_head[bucket];
-        count = 0;
+        h = &net->dev_name_head[get_bucket(*pos)];
         hlist_for_each_entry_rcu(dev, p, h, name_hlist) {
-                if (count++ == offset) {
-                        state->pos = set_bucket_offset(bucket, count);
+                if (++count == offset)
                         return dev;
-                }
         }
 
         return NULL;
 }
 
-static inline struct net_device *dev_from_new_bucket(struct seq_file *seq)
+static inline struct net_device *dev_from_bucket(struct seq_file *seq, loff_t *pos)
 {
-        struct dev_iter_state *state = seq->private;
         struct net_device *dev;
         unsigned int bucket;
 
-        bucket = get_bucket(state->pos);
         do {
-                dev = dev_from_same_bucket(seq);
+                dev = dev_from_same_bucket(seq, pos);
                 if (dev)
                         return dev;
 
-                bucket++;
-                state->pos = set_bucket_offset(bucket, 0);
+                bucket = get_bucket(*pos) + 1;
+                *pos = set_bucket_offset(bucket, 1);
         } while (bucket < NETDEV_HASHENTRIES);
 
         return NULL;
@@ -4088,33 +4075,20 @@ static inline struct net_device *dev_from_new_bucket(struct seq_file *seq)
 void *dev_seq_start(struct seq_file *seq, loff_t *pos)
         __acquires(RCU)
 {
-        struct dev_iter_state *state = seq->private;
-
         rcu_read_lock();
         if (!*pos)
                 return SEQ_START_TOKEN;
 
-        /* check for end of the hash */
-        if (state->pos == 0 && *pos > 1)
+        if (get_bucket(*pos) >= NETDEV_HASHENTRIES)
                 return NULL;
 
-        return dev_from_new_bucket(seq);
+        return dev_from_bucket(seq, pos);
 }
 
 void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
-        struct net_device *dev;
-
         ++*pos;
-
-        if (v == SEQ_START_TOKEN)
-                return dev_from_new_bucket(seq);
-
-        dev = dev_from_same_bucket(seq);
-        if (dev)
-                return dev;
-
-        return dev_from_new_bucket(seq);
+        return dev_from_bucket(seq, pos);
 }
 
 void dev_seq_stop(struct seq_file *seq, void *v)
@@ -4213,13 +4187,7 @@ static const struct seq_operations dev_seq_ops = {
 static int dev_seq_open(struct inode *inode, struct file *file)
 {
         return seq_open_net(inode, file, &dev_seq_ops,
-                            sizeof(struct dev_iter_state));
-}
-
-int dev_seq_open_ops(struct inode *inode, struct file *file,
-                     const struct seq_operations *ops)
-{
-        return seq_open_net(inode, file, ops, sizeof(struct dev_iter_state));
+                            sizeof(struct seq_net_private));
 }
 
 static const struct file_operations dev_seq_fops = {
diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
index 29c07fef9228..626698f0db8b 100644
--- a/net/core/dev_addr_lists.c
+++ b/net/core/dev_addr_lists.c
@@ -696,7 +696,8 @@ static const struct seq_operations dev_mc_seq_ops = {
 
 static int dev_mc_seq_open(struct inode *inode, struct file *file)
 {
-        return dev_seq_open_ops(inode, file, &dev_mc_seq_ops);
+        return seq_open_net(inode, file, &dev_mc_seq_ops,
+                            sizeof(struct seq_net_private));
 }
 
 static const struct file_operations dev_mc_seq_fops = {