Re: blk_iopoll_enabled

[Jens Axboe <axboe@kernel.dk>]

On 2014-03-12 11:35, Sagi Grimberg wrote:
> Hey Jens,
>
> So I'm looking at blk_iopoll for iSER & SRP and I have one gap I would
> like to get your input on.
>
> In blk-iopoll.c I see:
> int blk_iopoll_enabled = 1;
> EXPORT_SYMBOL(blk_iopoll_enabled);
>
> This is set to 1 and exported for everyone to condition and *modify* it.
> The documentation says the user must check this when using blk_iopoll.
>
> My question is why? it should always be true shouldn't it?
> Moreover, isn't it better to protect it using a get() function of it?
> can't someone set it to 0 and shutdown the lights on everyone else?

We can kill it. IIRC, it was mostly used during development to test 
functionality and performance (and wired to a sysfs toggle file).

But... Just because it's exported doesn't mean that random users are 
allowed to just disable it. What's left now is an always-on, so we can 
remove it.

-- 
Jens Axboe