Re: [Qemu-devel] [RFC 03/10] replace spinlock by QemuMutex.

[Frederic Konrad <fred.konrad@greensocs.com>]

On 29/01/2015 16:25, Peter Maydell wrote:
> On 16 January 2015 at 17:19,  <fred.konrad@greensocs.com> wrote:
>> From: KONRAD Frederic <fred.konrad@greensocs.com>
>>
>> spinlock is only used in two cases:
>>    * cpu-exec.c: to protect TranslationBlock
>>    * mem_helper.c: for lock helper in target-i386 (which seems broken).
>>
>> It's a pthread_mutex_t in user-mode so better using QemuMutex directly in this
>> case.
>> It allows as well to reuse tb_lock mutex of TBContext in case of multithread
>> TCG.
>>
>> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>> ---
>>   cpu-exec.c               | 15 +++++++++++----
>>   include/exec/exec-all.h  |  4 ++--
>>   linux-user/main.c        |  6 +++---
>>   target-i386/mem_helper.c | 16 +++++++++++++---
>>   tcg/i386/tcg-target.c    |  8 ++++++++
>>   5 files changed, 37 insertions(+), 12 deletions(-)
>>
>> diff --git a/cpu-exec.c b/cpu-exec.c
>> index a4f0eff..1e7513c 100644
>> --- a/cpu-exec.c
>> +++ b/cpu-exec.c
>> @@ -335,7 +335,9 @@ int cpu_exec(CPUArchState *env)
>>       SyncClocks sc;
>>
>>       /* This must be volatile so it is not trashed by longjmp() */
>> +#if defined(CONFIG_USER_ONLY)
>>       volatile bool have_tb_lock = false;
>> +#endif
> This work should be removing ifdefs indicating differences between
> handling of user-only and softmmu regarding locking and threads,
> not adding new ones.
>
> -- PMM
True,
I tried to go step by step to be able to use tb_lock and remove spinlock 
(which is
qemu_mutex_lock with ifdefs) to avoid a big patch with a lot of changes.

The ifdefs should be removed later in the series (I think).

Fred