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Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU re
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections |
Date: |
Thu, 23 Jul 2015 10:56:19 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 07/22/2015 10:18 PM, Paolo Bonzini wrote:
> Otherwise, grace periods are detected too early!
We always use qemu_thread_create() in qemu. So I think we can do it like this:
wrapped_fn()
{
rcu_register_thread();
call thread_fn() here
rcu_unregister_thread();
}
So we will never forget to call rcu_register_thread() when creating a new
thread.
Thanks
Wen Congyang
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> cpus.c | 6 ++++++
> iothread.c | 5 +++++
> migration/migration.c | 4 ++++
> tests/test-rcu-list.c | 4 ++++
> util/rcu.c | 2 ++
> 5 files changed, 21 insertions(+)
>
> diff --git a/cpus.c b/cpus.c
> index b00a423..a822ce3 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -954,6 +954,8 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
> CPUState *cpu = arg;
> int r;
>
> + rcu_register_thread();
> +
> qemu_mutex_lock_iothread();
> qemu_thread_get_self(cpu->thread);
> cpu->thread_id = qemu_get_thread_id();
> @@ -995,6 +997,8 @@ static void *qemu_dummy_cpu_thread_fn(void *arg)
> sigset_t waitset;
> int r;
>
> + rcu_register_thread();
> +
> qemu_mutex_lock_iothread();
> qemu_thread_get_self(cpu->thread);
> cpu->thread_id = qemu_get_thread_id();
> @@ -1034,6 +1038,8 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
> {
> CPUState *cpu = arg;
>
> + rcu_register_thread();
> +
> qemu_mutex_lock_iothread();
> qemu_tcg_init_cpu_signals();
> qemu_thread_get_self(cpu->thread);
> diff --git a/iothread.c b/iothread.c
> index 6d2a33f..da6ce7b 100644
> --- a/iothread.c
> +++ b/iothread.c
> @@ -18,6 +18,7 @@
> #include "sysemu/iothread.h"
> #include "qmp-commands.h"
> #include "qemu/error-report.h"
> +#include "qemu/rcu.h"
>
> typedef ObjectClass IOThreadClass;
>
> @@ -31,6 +32,8 @@ static void *iothread_run(void *opaque)
> IOThread *iothread = opaque;
> bool blocking;
>
> + rcu_register_thread();
> +
> qemu_mutex_lock(&iothread->init_done_lock);
> iothread->thread_id = qemu_get_thread_id();
> qemu_cond_signal(&iothread->init_done_cond);
> @@ -45,6 +48,8 @@ static void *iothread_run(void *opaque)
> }
> aio_context_release(iothread->ctx);
> }
> +
> + rcu_unregister_thread();
> return NULL;
> }
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 86ca099..fd4f99b 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -22,6 +22,7 @@
> #include "block/block.h"
> #include "qapi/qmp/qerror.h"
> #include "qemu/sockets.h"
> +#include "qemu/rcu.h"
> #include "migration/block.h"
> #include "qemu/thread.h"
> #include "qmp-commands.h"
> @@ -917,6 +918,8 @@ static void *migration_thread(void *opaque)
> int64_t start_time = initial_time;
> bool old_vm_running = false;
>
> + rcu_register_thread();
> +
> qemu_savevm_state_header(s->file);
> qemu_savevm_state_begin(s->file, &s->params);
>
> @@ -1016,6 +1019,7 @@ static void *migration_thread(void *opaque)
> qemu_bh_schedule(s->cleanup_bh);
> qemu_mutex_unlock_iothread();
>
> + rcu_unregister_thread();
> return NULL;
> }
>
> diff --git a/tests/test-rcu-list.c b/tests/test-rcu-list.c
> index 4c5f62e..daa8bf4 100644
> --- a/tests/test-rcu-list.c
> +++ b/tests/test-rcu-list.c
> @@ -108,6 +108,8 @@ static void *rcu_q_reader(void *arg)
> long long n_reads_local = 0;
> struct list_element *el;
>
> + rcu_register_thread();
> +
> *(struct rcu_reader_data **)arg = &rcu_reader;
> atomic_inc(&nthreadsrunning);
> while (goflag == GOFLAG_INIT) {
> @@ -129,6 +131,8 @@ static void *rcu_q_reader(void *arg)
> qemu_mutex_lock(&counts_mutex);
> n_reads += n_reads_local;
> qemu_mutex_unlock(&counts_mutex);
> +
> + rcu_unregister_thread();
> return NULL;
> }
>
> diff --git a/util/rcu.c b/util/rcu.c
> index 7270151..cdcad67 100644
> --- a/util/rcu.c
> +++ b/util/rcu.c
> @@ -216,6 +216,8 @@ static void *call_rcu_thread(void *opaque)
> {
> struct rcu_head *node;
>
> + rcu_register_thread();
> +
> for (;;) {
> int tries = 0;
> int n = atomic_read(&rcu_call_count);
>
- [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Paolo Bonzini, 2015/07/22
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections,
Wen Congyang <=
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Christian Borntraeger, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Paolo Bonzini, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Wen Congyang, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Paolo Bonzini, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Wen Congyang, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Paolo Bonzini, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Wen Congyang, 2015/07/23
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Wen Congyang, 2015/07/24
- Re: [Qemu-devel] [PATCH] rcu: actually register threads that have RCU read-side critical sections, Paolo Bonzini, 2015/07/24