On 07/23/2015 06:42 PM, Paolo Bonzini wrote:
>
>
> On 23/07/2015 12:30, Christian Borntraeger wrote:
>> Am 22.07.2015 um 16:18 schrieb Paolo Bonzini:
>>> Otherwise, grace periods are detected too early!
>>
>> I guess this or Wens proposal is still necessary for 2.4?
>
> Yes. I think this is better for 2.4. There are threads that do not
> need RCU, for example the thread-pool.c worker threads, so it may just
If the thread doesn't use RCU, rcu_register_thread() is harmless, is it right?
> be simpler to add an assertion in rcu_register_thread. I'm just a bit
> wary of doing little more than the bare minimum in 2.4, because of the
> OS X failure that I didn't quite understand.
Which problem? I don't find it in the maillist. Do I miss something?
Thanks
Wen Congyang
>
> Paolo
>
>>
>>>
>>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
>>> ---
>>> 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);
>>>
>>
>>
>>
>
> .
>
