linux-kernel - Re: [PATCH v1 05/18] KVM: selftests/hardware_disable

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Date:   Thu, 27 Oct 2022 00:16:12 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Wei Wang <wei.w.wang@...el.com>
Cc:     pbonzini@...hat.com, dmatlack@...gle.com, vipinsh@...gle.com,
        ajones@...tanamicro.com, eric.auger@...hat.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 05/18] KVM: selftests/hardware_disable_test: code
 consolidation and cleanup

On Mon, Oct 24, 2022, Wei Wang wrote:
> Remove the unnecessary definition of the threads[] array, and use the
> helper functions to create and join threads.
> 
> Also move setting of the thread affinity to __vcpu_thread_create using
> attribute. This avoids an explicit step to set it after thread
> creation.

As David called out, please do this in a separate patch (one logical change per
patch).

> Signed-off-by: Wei Wang <wei.w.wang@...el.com>
> ---
>  .../selftests/kvm/hardware_disable_test.c     | 56 +++++--------------
>  1 file changed, 15 insertions(+), 41 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/hardware_disable_test.c b/tools/testing/selftests/kvm/hardware_disable_test.c
> index f5d59b9934f1..c212d34a6714 100644
> --- a/tools/testing/selftests/kvm/hardware_disable_test.c
> +++ b/tools/testing/selftests/kvm/hardware_disable_test.c
> @@ -8,7 +8,6 @@
>  #define _GNU_SOURCE
>  
>  #include <fcntl.h>
> -#include <pthread.h>
>  #include <semaphore.h>
>  #include <stdint.h>
>  #include <stdlib.h>
> @@ -59,64 +58,39 @@ static void *sleeping_thread(void *arg)
>  	pthread_exit(NULL);
>  }
>  
> -static inline void check_create_thread(pthread_t *thread, pthread_attr_t *attr,
> -				       void *(*f)(void *), void *arg)
> -{
> -	int r;
> -
> -	r = pthread_create(thread, attr, f, arg);
> -	TEST_ASSERT(r == 0, "%s: failed to create thread", __func__);
> -}
> -
> -static inline void check_set_affinity(pthread_t thread, cpu_set_t *cpu_set)
> -{
> -	int r;
> -
> -	r = pthread_setaffinity_np(thread, sizeof(cpu_set_t), cpu_set);
> -	TEST_ASSERT(r == 0, "%s: failed set affinity", __func__);
> -}
> -
> -static inline void check_join(pthread_t thread, void **retval)
> -{
> -	int r;
> -
> -	r = pthread_join(thread, retval);
> -	TEST_ASSERT(r == 0, "%s: failed to join thread", __func__);
> -}
> -
>  static void run_test(uint32_t run)
>  {
>  	struct kvm_vcpu *vcpu;
>  	struct kvm_vm *vm;
>  	cpu_set_t cpu_set;
> -	pthread_t threads[VCPU_NUM];
>  	pthread_t throw_away;
> -	void *b;
> +	pthread_attr_t attr;
>  	uint32_t i, j;
> +	int r;
>  
>  	CPU_ZERO(&cpu_set);
>  	for (i = 0; i < VCPU_NUM; i++)
>  		CPU_SET(i, &cpu_set);

Uh, what is this test doing?  I assume the intent is to avoid spamming all pCPUs
in the system, but I don't get the benefit of doing so.