Messages in this thread | | | Date | Thu, 20 Feb 2014 21:07:27 -0500 | From | Peter Hurley <> | Subject | Re: [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK |
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On 02/20/2014 08:59 PM, Tejun Heo wrote: > Hello, > > On Thu, Feb 20, 2014 at 08:44:46PM -0500, Peter Hurley wrote: >>> +static void fw_device_workfn(struct work_struct *work) >>> +{ >>> + struct fw_device *device = container_of(to_delayed_work(work), >>> + struct fw_device, work); >> >> I think this needs an smp_rmb() here. > > The patch is equivalent transformation and the whole thing is > guaranteed to have gone through pool->lock. No explicit rmb > necessary.
The spin_unlock_irq(&pool->lock) only guarantees completion of memory operations _before_ the unlock; memory operations which occur _after_ the unlock may be speculated before the unlock.
IOW, unlock is not a memory barrier for operations that occur after.
>> IOW, the beginning of the work function should act like a barrier in >> the same way that queue_work_on() (et. al.) already does. > > workqueue already has enough barriers; otherwise, the whole kernel > would have crumbled long time ago.
See above.
Regards, Peter Hurley
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