[ 060/167] [PATCH 01/26] net: fix /proc/net/dev regression

Ben Hutchings
2012-05-09T06:04:54Z

From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit 2def16ae6b0c77571200f18ba4be049b03d75579 ]

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/linux/netdevice.h | 2 --
net/core/dev.c | 58 ++++++++++-----------------------------------
net/core/dev_addr_lists.c | 3 ++-
3 files changed, 15 insertions(+), 48 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a82ad4d..cbeb586 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2536,8 +2536,6 @@ 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 55cd370..cd5050e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4102,54 +4102,41 @@ 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;
@@ -4162,33 +4149,20 @@ 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)
@@ -4287,13 +4261,7 @@ 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 febba51..277faef 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 = {
--
1.7.10