Use named error return for initProcess#start

[tedyu]

In initProcess#start, there is deferred func :

	defer func() {
		if err != nil {

Since the error return is not named, the above check doesn't cover all the cases.
e.g. a few lines below:

	if _, err := io.Copy(p.messageSockPair.parent, p.bootstrapData); err != nil {
		return newSystemErrorWithCause(err, "copying bootstrap data to pipe")

The check in deferred func doesn't check either err or, the actual returned error.

This PR changes the error return to be named.

[tedyu]

@hqhq @cyphar
Mind taking a look ?

[tedyu]

/cc @mrunalp

[tedyu]

The deferred func starting line 352 is duplicate with the one starting line 304.

I think the second deferred func can be removed.

[tedyu]

What happens is that the second deferred func is ineffective.
I checked every err variable after line 352: they are all local (newly declared) to the operation.

I will drop the second deferred func.

[kolyshkin]

@tedyu thanks for the patch! Coincidentally, I was looking into this part of code as well and ended up with a similar patch.

Some discussion about the code is provided at #1916 (review) (also, this is a PR to blame) and yet it doesn't explain the double defer.

I think the defer needs to be moved up a bit (before p.intelRdtManager.Apply() or even before p.manager.Apply()), otherwise, if p.intelRdtManager.Apply() fails, p.manager.Destroy() is not called.

@crosbymichael @giuseppe PTAL

[mrunalp]

LGTM

[mrunalp]

@AkihiroSuda ptal

[tedyu]

@kolyshkin
I have lifted the deferred func earlier.
Please take a look.

[tedyu]

@kolyshkin
Please let me know if there is anything else to be addressed.

[thaJeztah]

@crosbymichael ptal 🤗

[crosbymichael]

LGTM

[tedyu]

@crosbymichael @thaJeztah
Can this be merged ?

Thanks

[thaJeztah]

I'm not a maintainer in this repository; @AkihiroSuda @mrunalp PTAL?

[AkihiroSuda]

LGTM

[kolyshkin]

LGTM

/lgtm

[tedyu]

@mrunalp
Can you merge this ?

thanks

[tedyu]

Thanks @AkihiroSuda

[AkihiroSuda]

Signed-off-by: zyu

Please use your full name next time