On Mon, Aug 13, 2012 at 07:43:21PM -0700, John Fastabend wrote:
> Add lock to prevent a race with a file closing and also remove
> useless and ugly sscanf code. The extra code was never needed
> and the case it supposedly protected against is in fact handled
> correctly by sock_from_file as pointed out by Al Viro.
>
> CC: Neil Horman <nhor...@tuxdriver.com>
> Reported-by: Al Viro <v...@zeniv.linux.org.uk>
> Signed-off-by: John Fastabend <john.r.fastab...@intel.com>
> ---
>
> net/core/netprio_cgroup.c | 22 ++++------------------
> 1 files changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
> index ed0c043..f65dba3 100644
> --- a/net/core/netprio_cgroup.c
> +++ b/net/core/netprio_cgroup.c
> @@ -277,12 +277,6 @@ out_free_devname:
> void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
> {
> struct task_struct *p;
> - char *tmp = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
> -
> - if (!tmp) {
> - pr_warn("Unable to attach cgrp due to alloc failure!\n");
> - return;
> - }
>
> cgroup_taskset_for_each(p, cgrp, tset) {
> unsigned int fd;
> @@ -296,32 +290,24 @@ void net_prio_attach(struct cgroup *cgrp, struct
> cgroup_taskset *tset)
> continue;
> }
>
> - rcu_read_lock();
> + spin_lock(&files->file_lock);
> fdt = files_fdtable(files);
> for (fd = 0; fd < fdt->max_fds; fd++) {
> - char *path;
> struct file *file;
> struct socket *sock;
> - unsigned long s;
> - int rv, err = 0;
> + int err;
>
> file = fcheck_files(files, fd);
> if (!file)
> continue;
>
> - path = d_path(&file->f_path, tmp, PAGE_SIZE);
> - rv = sscanf(path, "socket:[%lu]", &s);
> - if (rv <= 0)
> - continue;
> -
> sock = sock_from_file(file, &err);
> - if (!err)
> + if (sock)
> sock_update_netprioidx(sock->sk, p);
> }
> - rcu_read_unlock();
> + spin_unlock(&files->file_lock);
> task_unlock(p);
> }
> - kfree(tmp);
> }
>
> static struct cftype ss_files[] = {
>
This looks ok to me, but I've already shown my inability to review code that
interfaces with VFS. Al, what do you think?
Neil
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