RE: [PATCH V3 3/7] Drivers: hv: vmbus: add APIs to send/recv hvsock packet and get the r/w-ability

From: Dan Carpenter
Sent: Wednesday, July 22, 2015 18:36
To: Dexuan Cui
On Wed, Jul 22, 2015 at 10:09:10AM +0000, Dexuan Cui wrote:

quoted

quoted

I'd suggest you do something like

    if (ret == -EAGIAIN)
        return 0;
    else if (ret)
        return ret;

to make it future-proof (e.g. when a new error is returned by
hv_ringbuffer_peek). And a comment would also be useful as it is unclear
why we silence errors here.

Hi Vitaly,
Thanks!
I think I made a mistake here:
the "if (ret != 0) return 0;" should be changed
to   "if (ret != 0) return ret;"

Usually 0 means success to me, so 
to me, "ret != 0" reads like "ret is not successful" and seems natural. 

The kind of usage is not rare in the kernel code:

decui@lin:~/linux-next$ grep 'if (ret != 0)' kernel/ include/ ipc/  -r  | wc -l
28
decui@lin:~/linux-next$ grep 'if (ret != 0)' drivers/   -r  | wc -l
1031
 

The double negative really doesn't not make the code more complicated.
I like using a quadruple negative instead.

	if (ret != 0 != 0)
		return ret;
dan carpenter

Hi Dan, I read this as a humor.  :-)

I'll take the suggestion and remember to use this in V4 and in future:
 
if (ret)
	return ret;

Thanks!

-- Dexuan