On Thursday, October 22, 2015 02:53:19 PM Richard Guy Briggs wrote:
> When auditd goes away (died, killed or shutdown, or net namespace shut
> down), there is no point in sleeping waiting for auditd to drain the
> queue since that message would be distined for the hold queue after the
> timeout anyways. This will needlessly have those processes wait the
> full default timeout of 60 seconds (audit_backlog_wait_time).
>
> Wake up the processes caught in the audit_backlog_wait queue when auditd
> is no longer present so they can be sent instead to the hold queue.
>
> Signed-off-by: Richard Guy Briggs <r...@redhat.com>
> ---
> kernel/audit.c | 6 +++++-
> 1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 34411af..688fa1e 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -425,6 +425,7 @@ restart:
> audit_log_lost(s);
> audit_pid = 0;
> audit_sock = NULL;
> + wake_up(&audit_backlog_wait);
> } else {
> pr_warn("re-scheduling(#%d) write to
> audit_pid=%d\n",
> attempts, audit_pid);
> @@ -882,6 +883,8 @@ static int audit_receive_msg(struct sk_buff *skb, struct
> nlmsghdr *nlh) audit_pid = new_pid;
> audit_nlk_portid = NETLINK_CB(skb).portid;
> audit_sock = skb->sk;
> + if (!audit_pid)
> + wake_up(&audit_backlog_wait);
> }
> if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
> err = audit_set_rate_limit(s.rate_limit);
I'm thinking it might be time for two small, static helper functions,
auditd_register() and auditd_unregister() (or similar, feel free to suggest
other names), that set/reset the various auditd state variables and handle the
wake_up() call. We're duplicating some code that is starting to get non-
trivial.
I'd also add a comment about why you are calling wake_up() in the unregister
function.
> @@ -1154,6 +1157,7 @@ static void __net_exit audit_net_exit(struct net *net)
> if (sock == audit_sock) {
> audit_pid = 0;
> audit_sock = NULL;
> + wake_up(&audit_backlog_wait);
> }
>
> RCU_INIT_POINTER(aunet->nlsk, NULL);
> @@ -1393,7 +1397,7 @@ struct audit_buffer *audit_log_start(struct
> audit_context *ctx, gfp_t gfp_mask, sleep_time = timeout_start +
> audit_backlog_wait_time - jiffies; if (sleep_time > 0) {
> sleep_time = wait_for_auditd(sleep_time);
> - if (sleep_time > 0)
> + if (audit_pid && sleep_time > 0)
> continue;
Perhaps handle this in wait_for_auditd()? Right now this is the only caller,
but if we use it elsewhere it seems like we would want the same logic.
--
paul moore
www.paul-moore.com
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