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
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.
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);
>>
>
>
>
