Re: [RFC][PATCH -mm take4 3/6] add interface for netconsole using sysfs

Andrew Morton
2007-04-20T04:06:35Z

On Wed, 18 Apr 2007 21:08:45 +0900 Keiichi KII <k-keiichi@bx.jp.nec.com> wrote:

> +static ssize_t store_local_port(struct netconsole_target *nt, const char *buf,
> + size_t count)
> +{
> + spin_lock(&target_list_lock);
> + nt->np.local_port = simple_strtol(buf, NULL, 10);
> + spin_unlock(&target_list_lock);
> +
> + return count;
> +}
> +
> +static ssize_t store_remote_port(struct netconsole_target *nt, const char *buf,
> + size_t count)
> +{
> + spin_lock(&target_list_lock);
> + nt->np.remote_port = simple_strtol(buf, NULL, 10);
> + spin_unlock(&target_list_lock);
> +
> + return count;
> +}

I think that you'll find that the locking in here does nothing useful and
can be removed.

Also, write_msg() can be called from IRQ context, so this lock _must_ be
taken with spin_lock_irq[save] basically everywhere - the code as-is can be
deadlocked.