Re: [Qemu-devel] [PATCH 14/16] cputlb: remove tb_lock from tlb_flush functions

["Alex Bennée" <alex.bennee@linaro.org>]

Emilio G. Cota <cota@braap.org> writes:

> The acquisition of tb_lock was added when the async tlb_flush
> was introduced in e3b9ca810 ("cputlb: introduce tlb_flush_* async work.")
>
> tb_lock was there to allow us to do memset() on the tb_jmp_cache's.
> However, since f3ced3c5928 ("tcg: consistently access cpu->tb_jmp_cache
> atomically") all accesses to tb_jmp_cache are atomic, so tb_lock
> is not needed here. Get rid of it.

\o/

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

>
> Signed-off-by: Emilio G. Cota <cota@braap.org>
> ---
>  accel/tcg/cputlb.c | 8 --------
>  1 file changed, 8 deletions(-)
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 0543903..f5c3a09 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -125,8 +125,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
>      atomic_set(&env->tlb_flush_count, env->tlb_flush_count + 1);
>      tlb_debug("(count: %zu)\n", tlb_flush_count());
>
> -    tb_lock();
> -
>      memset(env->tlb_table, -1, sizeof(env->tlb_table));
>      memset(env->tlb_v_table, -1, sizeof(env->tlb_v_table));
>      cpu_tb_jmp_cache_clear(cpu);
> @@ -135,8 +133,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
>      env->tlb_flush_addr = -1;
>      env->tlb_flush_mask = 0;
>
> -    tb_unlock();
> -
>      atomic_mb_set(&cpu->pending_tlb_flush, 0);
>  }
>
> @@ -180,8 +176,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu, run_on_cpu_data data)
>
>      assert_cpu_is_self(cpu);
>
> -    tb_lock();
> -
>      tlb_debug("start: mmu_idx:0x%04lx\n", mmu_idx_bitmask);
>
>      for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
> @@ -197,8 +191,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu, run_on_cpu_data data)
>      cpu_tb_jmp_cache_clear(cpu);
>
>      tlb_debug("done\n");
> -
> -    tb_unlock();
>  }
>
>  void tlb_flush_by_mmuidx(CPUState *cpu, uint16_t idxmap)


--
Alex Bennée