On 15-01-2008 07:36, Makito SHIOKAWA wrote:
> Fix some RTNL lock taking:
>
> * RTNL (mutex; may sleep) must not be taken under read_lock (spinlock; must be
> atomic). However, RTNL is taken under read_lock in bond_loadbalance_arp_mon()
> and bond_activebackup_arp_mon(). So change code to take RTNL outside of
> read_lock.
>
> * rtnl_unlock() calls netdev_run_todo() which takes net_todo_run_mutex, and
> rtnl_unlock() is called under read_lock in bond_mii_monitor(). So for the same
> reason as above, change code to call rtnl_unlock() outside of read_lock.
>
> Signed-off-by: Makito SHIOKAWA <[EMAIL PROTECTED]>
> ---
> drivers/net/bonding/bond_main.c | 24 ++++++++++--------------
> 1 file changed, 10 insertions(+), 14 deletions(-)
>
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2372,6 +2372,7 @@ void bond_mii_monitor(struct work_struct
> struct bonding *bond = container_of(work, struct bonding,
> mii_work.work);
> unsigned long delay;
> + int need_unlock = 0;
>
> read_lock(&bond->lock);
> if (bond->kill_timers) {
> @@ -2383,13 +2384,16 @@ void bond_mii_monitor(struct work_struct
> rtnl_lock();
> read_lock(&bond->lock);
> __bond_mii_monitor(bond, 1);
> - rtnl_unlock();
> + need_unlock = 1;
Maybe I'm wrong, but since this read_lock() is given and taken anyway,
it seems this looks a bit better to me (why hold this rtnl longer
than needed?):
read_unlock(&bond->lock);
rtnl_unlock();
read_lock(&bond->lock);
On the other hand, probably 'if (bond->kill_timers)' could be repeated
after this read_lock() retaking.
> }
>
> delay = ((bond->params.miimon * HZ) / 1000) ? : 1;
> - read_unlock(&bond->lock);
> if (bond->params.miimon)
> queue_delayed_work(bond->wq, &bond->mii_work, delay);
If this if () is really necessary here, then this should be better
before "delay = ..." with a block.
> + read_unlock(&bond->lock);
> + /* rtnl_unlock() may sleep, so call it after read_unlock() */
> + if (need_unlock)
> + rtnl_unlock();
> }
Regards,
Jarek P.
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