Re: poll: allow f_op->poll to sleep, take #3

[Tejun Heo <htejun@gmail.com>]

Ingo Molnar wrote:
>> And @sync might be useful depending on who's waking it up, so we 
>> either need to change the wake interface or give it an easier way to 
>> pass those parameters as received.  The callback function isn't the 
>> right place to ignore those parameters.  It simply doesn't know why 
>> the caller is passing them in or what they mean under the 
>> circumstances.
> 
> We'll likely eliminate the 'sync' parameter from the scheduler. It's 
> not a flag that should be proliferated.

But it's still being used in quite hot paths (pipe, splice, socket)
and I don't really wanna mix up a change which can cause subtle
scheduling related performance regression into this patch.  How about
using the dummy waitqueue hack for now and when removing the @sync
param, switch it to one of wakeup APIs?  I'll be happy to add big /*
TODO */ comment in the function.

Thanks.

-- 
tejun