On Mon, 18 Sep 2017, Luck, Tony wrote:
> @@ -208,14 +241,19 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file
> *of,
> char *tok, *resname;
> int closid, ret = 0;
>
> + seq_buf_clear(&last_cmd_status);
> +
> /* Valid input requires a trailing newline */
> - if (nbytes == 0 || buf[nbytes - 1] != '\n')
> + if (nbytes == 0 || buf[nbytes - 1] != '\n') {
> + seq_buf_puts(&last_cmd_status, "no trailing newline\n");
> return -EINVAL;
> + }
> buf[nbytes - 1] = '\0';
In all other instances you access last_cmd_status within the
rdtgroup_kn_lock_live() protected section, which also serializes the show()
function via rdtgroup_mutex. Here you do it outside for obvious reasons,
but that opens a can of evil worms ...
Can you please provide and use two helpers - last_cmd_buf_clear() and
last_cmd_buf_puts() - which both have a
lockdep_assert_held(&rdtgroup_mutex) inside to make sure that we don't end
up with unprotected access accidentally?
Thanks,
tglx
