Re: [PATCH v2 03/14] system: unconditionally enable thread naming

[Richard Henderson <richard.henderson@linaro.org>]

On 8/30/25 04:03, Daniel P. Berrangé wrote:
> When thread naming was introduced years ago, it was disabled by
> default and put behind a command line flag:
> 
>    commit 8f480de0c91a18d550721f8d9af969ebfbda0793
>    Author: Dr. David Alan Gilbert<dgilbert@redhat.com>
>    Date:   Thu Jan 30 10:20:31 2014 +0000
> 
>      Add 'debug-threads' suboption to --name
> 
> This was done based on a concern that something might depend
> on the historical thread naming. Thread names, however, were
> never promised to be part of QEMU's public API. The defaults
> will vary across platforms, so no assumptions should ever be
> made about naming.
> 
> An opt-in behaviour is also unfortunately incompatible with
> RCU which creates its thread from an constructor function
> which is run before command line args are parsed. Thus the
> RCU thread lacks any name.
> 
> libvirt has unconditionally enabled debug-threads=yes on all
> VMs it creates for 10 years. Interestingly this DID expose a
> bug in libvirt, as it parsed/proc/$PID/stat and could not
> cope with a space in the thread name. This was a latent
> pre-existing bug in libvirt though, and not a part of QEMU's
> API.
> 
> Having thread names always available, will allow thread names
> to be included in error reports and log messags QEMU prints
> by default, which will improve ability to triage QEMU bugs.
> 
> Reviewed-by: Dr. David Alan Gilbert<dave@treblig.org>
> Signed-off-by: Daniel P. Berrangé<berrange@redhat.com>
> ---
>   docs/about/deprecated.rst |  7 +++++++
>   include/qemu/thread.h     |  1 -
>   system/vl.c               | 11 ++++++-----
>   util/qemu-thread-posix.c  | 18 +-----------------
>   util/qemu-thread-win32.c  | 27 ++++++---------------------
>   5 files changed, 20 insertions(+), 44 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~