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?

Signed-off-by: Laine Stump <laine@redhat.com> ---

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

src/qemu/qemu_process.c | 6 ------ 1 file changed, 6 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 126fabf5ef..832b2e6870 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -6907,12 +6907,6 @@ qemuProcessLaunch(virConnectPtr conn, goto cleanup; VIR_DEBUG("Handshake complete, child running");

- if (rv == -1) { - /* The VM failed to start; tear filters before taps */ - virDomainConfVMNWFilterTeardown(vm); - goto cleanup; - } - if (qemuDomainObjStartWorker(vm) < 0) goto cleanup;