[libvirt PATCH] qemu: remove unreachable code in qemuProcessStart()

[Laine Stump]

On 8/24/20 6:30 PM, Daniel Henrique Barboza wrote:
> 
> 
> On 8/23/20 1:51 AM, Laine Stump wrote:
>> Back when the original version of this chunk of code was added (commit
>> 41b087198 in libvirt-0.8.1 in April 2010), we used virExecDaemonize()
>> to start the qemu process, and would continue on in the function
>> (which at that time was called qemudStartVMDaemon()) even if a -1 was
>> returned. So it was possible to get to this code with rv == -1 (it was
>> called "ret" in that version of the code).
>>
>> In modern libvirt code, qemu is started with virCommandRun(); then we
>> call virPidFileReadPath(); those are the only two ways of setting "rv"
>> prior to this code being removed, and in either case if the new value
>> of rv < 0, then we immediately skip over the rest of the code to the
>> cleanup: label.
>>
>> This means that the code being removed by this patch is
>> unreachable.
>>
>> (NB: anyway, attempting to fend off accidental removal of some other
>> guest's nwfilter rules by carefully ordering all nwfilter teardowns to
>> happen "before tap device deletion" is a fruitless pursuit, because a
>> tap device could be deleted by the qemu process being terminated
>> external to libvirt, i.e. we must instead avoid re-using tap device
>> names. That is coming.)
> 
> 
> Is it better for this patch to be pushed after "conf: properly clear out
> autogenerated macvtap ..." then?

Nah, it's unreachable code in any case, so its removal is independent of 
anything else.

> 
>>
>> Signed-off-by: Laine Stump <laine at redhat.com>
>> ---
> 
> Reviewed-by: Daniel Henrique Barboza <danielhb413 at gmail.com>

Thanks!