netdev - Re: any reason for "!!netif_carrier_ok" and "!!netif

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Message-ID: <20180827121623.Horde.Jfv_6y4hNg2t7I9Trd8TLaD@crashcourse.ca>
Date:   Mon, 27 Aug 2018 12:16:23 -0400
From:   rpjday@...shcourse.ca
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: any reason for "!!netif_carrier_ok" and "!!netif_dormant" in
 net-sysfs.c?

Quoting David Miller <davem@...emloft.net>:

> From: "Robert P. J. Day" <rpjday@...shcourse.ca>
> Date: Mon, 27 Aug 2018 04:55:29 -0400 (EDT)
>
>>   another pedantic oddity -- is there a reason for these two double
>> negations in net/core/net-sysfs.c?
>
> It turns an arbitrary integer into a boolean, this is a common
> construct across the kernel tree so I'm surprised you've never seen
> it before.
>
> Although, I don't know how much more hand holding we're willing to
> tolerate continuing to give to you at this point.
>
> Thanks.

   I mentioned in my earlier email that I know what that construct is
*typically* used for; I also pointed out that, AFAICT, it was totally
unnecessary in the context of the two routines I mentioned, which
would appear to ever return only one of two boolean values, 0 or 1.

   My experience with kernel code is that one should not introduce
unnecessary complexities, which suggests (as I stated) that there
seems to be no value in the "!!" construct *in those particular
cases*, hence my curiosity.

   If you want to criticize my question, at least have the courtesy
to represent it accurately.

rday