Re: [PATCH 2/5] cpu: move Qemu[Thread|Cond] setup into common code

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 30/5/24 21:42, Alex Bennée wrote:
> Aside from the round robin threads this is all common code. By
> moving the halt_cond setup we also no longer need hacks to work around
> the race between QOM object creation and thread creation.
> 
> It is a little ugly to free stuff up for the round robin thread but
> better it deal with its own specialises than making the other
> accelerators jump through hoops.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   include/hw/core/cpu.h             |  4 ++++
>   accel/dummy-cpus.c                |  3 ---
>   accel/hvf/hvf-accel-ops.c         |  4 ----
>   accel/kvm/kvm-accel-ops.c         |  3 ---
>   accel/tcg/tcg-accel-ops-mttcg.c   |  4 ----
>   accel/tcg/tcg-accel-ops-rr.c      | 14 +++++++-------
>   hw/core/cpu-common.c              |  5 +++++
>   target/i386/nvmm/nvmm-accel-ops.c |  3 ---
>   target/i386/whpx/whpx-accel-ops.c |  3 ---
>   9 files changed, 16 insertions(+), 27 deletions(-)


> diff --git a/accel/tcg/tcg-accel-ops-rr.c b/accel/tcg/tcg-accel-ops-rr.c
> index 894e73e52c..84c36c1450 100644
> --- a/accel/tcg/tcg-accel-ops-rr.c
> +++ b/accel/tcg/tcg-accel-ops-rr.c
> @@ -317,22 +317,22 @@ void rr_start_vcpu_thread(CPUState *cpu)
>       tcg_cpu_init_cflags(cpu, false);
>   
>       if (!single_tcg_cpu_thread) {
> -        cpu->thread = g_new0(QemuThread, 1);
> -        cpu->halt_cond = g_new0(QemuCond, 1);
> -        qemu_cond_init(cpu->halt_cond);
> +        single_tcg_halt_cond = cpu->halt_cond;
> +        single_tcg_cpu_thread = cpu->thread;
>   
>           /* share a single thread for all cpus with TCG */
>           snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "ALL CPUs/TCG");
>           qemu_thread_create(cpu->thread, thread_name,
>                              rr_cpu_thread_fn,
>                              cpu, QEMU_THREAD_JOINABLE);
> -
> -        single_tcg_halt_cond = cpu->halt_cond;
> -        single_tcg_cpu_thread = cpu->thread;
>       } else {
> -        /* we share the thread */
> +        /* we share the thread, dump spare data */

/* we share the thread, release allocations from cpu_common_initfn() */

> +        g_free(cpu->thread);
> +        qemu_cond_destroy(cpu->halt_cond);
>           cpu->thread = single_tcg_cpu_thread;
>           cpu->halt_cond = single_tcg_halt_cond;
> +
> +        /* copy the stuff done at start of rr_cpu_thread_fn */
>           cpu->thread_id = first_cpu->thread_id;
>           cpu->neg.can_do_io = 1;
>           cpu->created = true;

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>