On Thu, Feb 16, 2023 at 17:23:19 +0100, Peter Krempa wrote: > On Tue, Feb 14, 2023 at 11:08:12 -0600, Jonathon Jongsma wrote: > > Adds the ability to monitor the nbdkit process so that we can take > > action in case the child exits unexpectedly. > > > > When the nbdkit process exits, we pause the vm, restart nbdkit, and then > > resume the vm. This allows the vm to continue working in the event of a > > nbdkit failure. > > > > Eventually we may want to generalize this functionality since we may > > need something similar for e.g. qemu-storage-daemon, etc. > > > > The process is monitored with the pidfd_open() syscall if it exists > > (since linux 5.3). Otherwise it resorts to checking whether the process > > is alive once a second. The one-second time period was chosen somewhat > > arbitrarily. > > > > Signed-off-by: Jonathon Jongsma <jjongsma@xxxxxxxxxx> > > --- > > meson.build | 7 ++ > > src/qemu/qemu_nbdkit.c | 147 ++++++++++++++++++++++++++++++++++++++-- > > src/qemu/qemu_nbdkit.h | 4 +- > > src/qemu/qemu_process.c | 4 +- > > 4 files changed, 155 insertions(+), 7 deletions(-) > > [...] > > > diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c > > index e6d3232a1e..74e2ceee19 100644 > > --- a/src/qemu/qemu_nbdkit.c > > +++ b/src/qemu/qemu_nbdkit.c > > [...] > > > +#if WITH_DECL_SYS_PIDFD_OPEN > > + pidfd = syscall(SYS_pidfd_open, proc->pid, 0); > > + if (pidfd < 0) > > + return -1; > > + > > + proc->eventwatch = virEventAddHandle(pidfd, > > + VIR_EVENT_HANDLE_READABLE, > > + qemuNbdkitProcessPidfdCb, > > + qemuNbdkitProcessEventDataNew(proc, vm), > > + (virFreeCallback)qemuNbdkitProcessEventDataFree); > > +#else > > + /* fall back to checking once a second */ > > + proc->eventwatch = virEventAddTimeout(1000, > > + qemuNbdkitProcessTimeoutCb, > > + qemuNbdkitProcessEventDataNew(proc, vm), > > + (virFreeCallback)qemuNbdkitProcessEventDataFree); > > I don't think we want to do this this polling. I'll rather disable all > of nbdkit than do this if the event interface is not available. > > Additionally any failure in this function would result into the default > error of "unable to connect to nbdkit" but this time with no > information. If you get rid of the polling impl: Reviewed-by: Peter Krempa <pkrempa@xxxxxxxxxx>
