Re: [PATCH 2/2] trace: skip qemu_set_log_filename if no "-D" option was passed

[Eric Blake]

On 2/9/21 8:57 AM, Paolo Bonzini wrote:
> When the "simple" backend is not active but the "log" backend is,
> both "-trace file=" and "-D" will result in a call to
> qemu_set_log_filename.  Unfortunately, QEMU was also calling
> qemu_set_log_filename if "-D" was not passed, so the "-trace
> file=" option had no effect and the tracepoints went back to
> stderr.
> 
> Fortunately we can just skip qemu_set_log_filename in that case,
> because the log backend will initialize itself just fine as soon
> as qemu_set_log is called, also in qemu_process_early_options.
> 
> Cc: stefanha@redhat.com
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  softmmu/vl.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index b219ce1f35..e67f91dd37 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2367,7 +2367,9 @@ static void qemu_process_early_options(void)
>      trace_init_file();
>  
>      /* Open the logfile at this point and set the log mask if necessary.  */
> -    qemu_set_log_filename(log_file, &error_fatal);
> +    if (log_file) {
> +        qemu_set_log_filename(log_file, &error_fatal);
> +    }
>      if (log_mask) {
>          int mask;
>          mask = qemu_str_to_log_mask(log_mask);
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org