From: Ananyev, Konstantin [mailto:konstantin.ananyev@intel.com]
Sent: Thursday, 2 December 2021 14.01

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From: Thomas Monjalon [mailto:thomas@monjalon.net]
Sent: Thursday, 2 December 2021 08.19

01/12/2021 22:37, Tyler Retzlaff:

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On Wed, Nov 24, 2021 at 06:04:56PM +0000, Bruce Richardson wrote:

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  if (ret < 0 && rte_errno == EAGAIN)

i only urge that this be explicit as opposed to a range i.e. ret

== -

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1

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preferred over ret < 0

I don't understand why you think it is important to limit return

value

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to -1.
Why "if (ret == -1)" is better than "if (ret < 0)" ?

Speaking for myself:

For clarity. It leaves no doubt that "it failed" is represented by

the return value -1, and that the function does not return errno values
such as

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-EINVAL.

But why '< 0' gives you less clarity?
Negative value means failure - seems perfectly clear to me.

I disagree: Negative value does not mean failure. Only -1 means failure.

There is no -2 return value. There is no -EINVAL return value.

Testing for (ret < 0) might confuse someone to think that other values than -1 could be returned as indication of failure, which is not the case when following the convention where the functions set errno and return -1 in case of failure.

It would be different if following a convention where the functions return -errno in case of failure. In this case, testing (ret < 0) would be appropriate.

So explicitly testing (ret == -1) clarifies which of the two conventions are relevant.