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Date: Fri, 29 Jul 2011 10:49:01 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] Odd code in cpus.c
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To: Frediano Ziglio <freddy77@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On 2011-07-29 10:34, Frediano Ziglio wrote:
> I  don't know that much this code however qemu_kvm_init_cpu_signals
> seems a bit strange and duplicate to me, in cpus.c
> 
> 
> static void qemu_kvm_init_cpu_signals(CPUState *env)
> {
>     int r;
>     sigset_t set;
>     struct sigaction sigact;
> 
>     memset(&sigact, 0, sizeof(sigact));
>     sigact.sa_handler = dummy_signal;
>     sigaction(SIG_IPI, &sigact, NULL);
> 
> #ifdef CONFIG_IOTHREAD
>     pthread_sigmask(SIG_BLOCK, NULL, &set);
>     sigdelset(&set, SIG_IPI);
>     sigdelset(&set, SIGBUS);
>     r = kvm_set_signal_mask(env, &set);
>     if (r) {
>         fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r));
>         exit(1);
>     }
> #else
>     sigemptyset(&set);
>     sigaddset(&set, SIG_IPI);
>     sigaddset(&set, SIGIO);
>     sigaddset(&set, SIGALRM);
>     pthread_sigmask(SIG_BLOCK, &set, NULL);
> 
>     pthread_sigmask(SIG_BLOCK, NULL, &set);
>     sigdelset(&set, SIGIO);
>     sigdelset(&set, SIGALRM);
> #endif
>     sigdelset(&set, SIG_IPI);
>     sigdelset(&set, SIGBUS);
>     r = kvm_set_signal_mask(env, &set);
>     if (r) {
>         fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r));
>         exit(1);
>     }
> }
> 
> 
> if CONFIG_IOTHREAD is set you get
> 
> 
> static void qemu_kvm_init_cpu_signals(CPUState *env)
> {
>     int r;
>     sigset_t set;
>     struct sigaction sigact;
> 
>     memset(&sigact, 0, sizeof(sigact));
>     sigact.sa_handler = dummy_signal;
>     sigaction(SIG_IPI, &sigact, NULL);
> 
>     pthread_sigmask(SIG_BLOCK, NULL, &set);
>     sigdelset(&set, SIG_IPI);
>     sigdelset(&set, SIGBUS);
>     r = kvm_set_signal_mask(env, &set);
>     if (r) {
>         fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r));
>         exit(1);
>     }
>     sigdelset(&set, SIG_IPI);
>     sigdelset(&set, SIGBUS);
>     r = kvm_set_signal_mask(env, &set);
>     if (r) {
>         fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r));
>         exit(1);
>     }
> }
> 
> 
> which seems to set kvm signal twice with same values (taking into
> account that in kvm_set_signal_mask the set is copied before the call
> to kvm_vcpu_ioctl).

Indeed. Harmless fortunately. I suspect the duplicate bits in the #ifdef
CONFIG_IOTHREAD block were simply forgotten. Paolo?

Jan

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