(Adding netdev@...)
On Wed, Oct 29, 2014 at 9:16 AM, Peter Zijlstra <pet...@infradead.org> wrote:
>
> Dave, this relies on bits currently in tip/sched/core, if you're ok I'll
> merge it through that tree.
>
> ---
> Subject: netdev: Fix sleeping inside wait event
> From: Peter Zijlstra <pet...@infradead.org>
> Date: Wed Oct 29 17:04:56 CET 2014
>
> rtnl_lock_unregistering() takes rtnl_lock() -- a mutex -- inside a
> wait loop. The wait loop relies on current->state to function, but so
> does mutex_lock(), nesting them makes for the inner to destroy the
> outer state.
>
While you are on it, please fix rtnl_lock_unregistering_all() too?
Thanks!
> Fix this using the new wait_woken() bits.
>
> Cc: Oleg Nesterov <o...@redhat.com>
> Cc: Eric Biederman <ebied...@xmission.com>
> Cc: David Miller <da...@davemloft.net>
> Reported-by: Fengguang Wu <fengguang...@intel.com>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> ---
> net/core/dev.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -7196,11 +7196,10 @@ static void __net_exit rtnl_lock_unregis
> */
> struct net *net;
> bool unregistering;
> - DEFINE_WAIT(wait);
> + DEFINE_WAIT_FUNC(wait, woken_wake_function);
>
> + add_wait_queue(&netdev_unregistering_wq, &wait);
> for (;;) {
> - prepare_to_wait(&netdev_unregistering_wq, &wait,
> - TASK_UNINTERRUPTIBLE);
> unregistering = false;
> rtnl_lock();
> list_for_each_entry(net, net_list, exit_list) {
> @@ -7212,9 +7211,10 @@ static void __net_exit rtnl_lock_unregis
> if (!unregistering)
> break;
> __rtnl_unlock();
> - schedule();
> +
> + wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
> }
> - finish_wait(&netdev_unregistering_wq, &wait);
> + remove_wait_queue(&netdev_unregistering_wq, &wait);
> }
>
> static void __net_exit default_device_exit_batch(struct list_head *net_list)
> --
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