Re: [pve-devel] [PATCH qemu-server 2/2] swtpm: wait for pidfile

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

On 14.10.21 11:28, Stefan Reiter wrote:
> swtpm may take a little bit to daemonize, so the pidfile might not be
> available right after run_command. Causes an ugly warning about using an
> undefined value in a match, so wait up to 5s for it to appear.
> 
> Note that in testing this loop only ever got to the first or second
> iteration, so I believe the timeout duration should be more than enough.
> 
> Also add a missing 'usleep' import, 'usleep' was used before but never
> imported, apparently the other case never got triggered...
> 
> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> ---
> 
> Triggered during rollback testing, potentially due to extra load. Didn't cause
> any failure (as long as the VM starts fine it's all good), but looks ugly in the
> log and may cause lingering instances if QEMU fails afterward.
> 
>  PVE/QemuServer.pm | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index d5dfdbb..7a7cdb0 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -22,7 +22,7 @@ use JSON;
>  use MIME::Base64;
>  use POSIX;
>  use Storable qw(dclone);
> -use Time::HiRes qw(gettimeofday);
> +use Time::HiRes qw(gettimeofday usleep);
>  use URI::Escape;
>  use UUID;
>  
> @@ -3059,6 +3059,14 @@ sub start_swtpm {
>      push @$emulator_cmd, "--tpm2" if $tpm->{version} eq 'v2.0';
>      run_command($emulator_cmd, outfunc => sub { print $1; });
>  
> +    # swtpm may take a bit to start before daemonizing, wait up to 5s for pid
> +    my $tries = 100;
> +    while (! -e $paths->{pid}) {
> +	usleep(50000);
> +	die "failed to start swtpm: pid file '$paths->{pid}' wasn't created.\n"
> +	    if --$tries == 0;

I moved the die before the sleep, as else we'd wait extra 50 ms if we'd die anyway.

> +    }
> +
>      # return untainted PID of swtpm daemon so it can be killed on error
>      file_read_firstline($paths->{pid}) =~ m/(\d+)/;
>      return $1;
>