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SubjectRe: [PATCH] net: Revert "fib_trie: use seq_file_net rather than seq->private"
On 06/05/2014 02:02 AM, Sasha Levin wrote:

> This reverts commit 30f38d2fdd79f13fc929489f7e6e517b4a4bfe63.

> fib_triestat is surrounded by a big lie: while it claims that it's a
> seq_file (fib_triestat_seq_open, fib_triestat_seq_show), it isn't:

> static const struct file_operations fib_triestat_fops = {
> .owner = THIS_MODULE,
> .open = fib_triestat_seq_open,
> .read = seq_read,
> .llseek = seq_lseek,
> .release = single_release_net,
> };

> Yes, fib_triestat is just a regular file.

> A small detail (assuming CONFIG_NET_NS=y) is that while for seq_files
> you could do seq_file_net() to get the net ptr, doing so for a regular
> file would be wrong and would dereference an invalid pointer.
>
> The fib_triestat lie claimed a victim, and trying to show the file would
> be bad for the kernel. This patch just reverts the issue and fixes
> fib_triestat, which still needs a rewrite to either be a seq_file or
> stop claiming it is.

> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
> net/ipv4/fib_trie.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 243c7f4..5afeb5a 100644
> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
> @@ -2166,7 +2166,7 @@ static void fib_table_print(struct seq_file *seq, struct fib_table *tb)
>
> static int fib_triestat_seq_show(struct seq_file *seq, void *v)
> {
> - struct net *net = seq_file_net(seq);
> + struct net *net = (struct net *)seq->private;

'void *' doesn't need any explicit casting to another pointer type, the
cast it automatic.

WBR, Sergei



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