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    Subject[PATCH 11/40] ipv6/flowlabel: simplify pid namespace lookup
    Date
    The shole seq_file sequence already operates under a single RCU lock pair,
    so move the pid namespace lookup into it, and stop grabbing a reference
    and remove all kinds of boilerplate code.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    net/ipv6/ip6_flowlabel.c | 28 +++++-----------------------
    1 file changed, 5 insertions(+), 23 deletions(-)

    diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
    index c05c4e82a7ca..a9f221d45ef9 100644
    --- a/net/ipv6/ip6_flowlabel.c
    +++ b/net/ipv6/ip6_flowlabel.c
    @@ -754,7 +754,10 @@ static struct ip6_flowlabel *ip6fl_get_idx(struct seq_file *seq, loff_t pos)
    static void *ip6fl_seq_start(struct seq_file *seq, loff_t *pos)
    __acquires(RCU)
    {
    + struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
    +
    rcu_read_lock_bh();
    + state->pid_ns = task_active_pid_ns(current);
    return *pos ? ip6fl_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
    }

    @@ -810,36 +813,15 @@ static const struct seq_operations ip6fl_seq_ops = {

    static int ip6fl_seq_open(struct inode *inode, struct file *file)
    {
    - struct seq_file *seq;
    - struct ip6fl_iter_state *state;
    - int err;
    -
    - err = seq_open_net(inode, file, &ip6fl_seq_ops,
    + return seq_open_net(inode, file, &ip6fl_seq_ops,
    sizeof(struct ip6fl_iter_state));
    -
    - if (!err) {
    - seq = file->private_data;
    - state = ip6fl_seq_private(seq);
    - rcu_read_lock();
    - state->pid_ns = get_pid_ns(task_active_pid_ns(current));
    - rcu_read_unlock();
    - }
    - return err;
    -}
    -
    -static int ip6fl_seq_release(struct inode *inode, struct file *file)
    -{
    - struct seq_file *seq = file->private_data;
    - struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
    - put_pid_ns(state->pid_ns);
    - return seq_release_net(inode, file);
    }

    static const struct file_operations ip6fl_seq_fops = {
    .open = ip6fl_seq_open,
    .read = seq_read,
    .llseek = seq_lseek,
    - .release = ip6fl_seq_release,
    + .release = seq_release_net,
    };

    static int __net_init ip6_flowlabel_proc_init(struct net *net)
    --
    2.17.0
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