Re: [Qemu-devel] [RFC PATCH v8 05/21] replay: introduce mutex to protect the replay log

[Paolo Bonzini <pbonzini@redhat.com>]

On 22/01/2015 09:51, Pavel Dovgalyuk wrote:
> This mutex will protect read/write operations for replay log.
> Using mutex is necessary because most of the events consist of
> several fields stored in the log. The mutex will help to avoid races.
> 
> Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
> ---
>  replay/replay-internal.c |   25 +++++++++++++++++++++++++
>  replay/replay-internal.h |    7 +++++++
>  2 files changed, 32 insertions(+), 0 deletions(-)
> 
> diff --git a/replay/replay-internal.c b/replay/replay-internal.c
> index 3865fa5..f552dad 100755
> --- a/replay/replay-internal.c
> +++ b/replay/replay-internal.c
> @@ -15,6 +15,11 @@
>  unsigned int replay_data_kind = -1;
>  unsigned int replay_has_unread_data;
>  
> +/* Mutex to protect reading and writing events to the log.
> +   replay_data_kind and replay_has_unread_data are also protected
> +   by this mutex. */
> +static QemuMutex lock;
> +
>  /* File for replay writing */
>  FILE *replay_file;
>  
> @@ -139,3 +144,23 @@ void replay_fetch_data_kind(void)
>          }
>      }
>  }
> +
> +void replay_mutex_init(void)
> +{
> +    qemu_mutex_init(&lock);
> +}
> +
> +void replay_mutex_destroy(void)
> +{
> +    qemu_mutex_destroy(&lock);
> +}

Destroy is probably not necessary.

> +void replay_mutex_lock(void)
> +{
> +    qemu_mutex_lock(&lock);
> +}
> +
> +void replay_mutex_unlock(void)
> +{
> +    qemu_mutex_unlock(&lock);
> +}
> diff --git a/replay/replay-internal.h b/replay/replay-internal.h
> index dad5bc8..50ce29b 100755
> --- a/replay/replay-internal.h
> +++ b/replay/replay-internal.h
> @@ -34,6 +34,13 @@ int64_t replay_get_qword(void);
>  void replay_get_array(uint8_t *buf, size_t *size);
>  void replay_get_array_alloc(uint8_t **buf, size_t *size);
>  
> +/* Mutex functions for protecting replay log file */
> +
> +void replay_mutex_init(void);
> +void replay_mutex_destroy(void);
> +void replay_mutex_lock(void);
> +void replay_mutex_unlock(void);
> +
>  /*! Checks error status of the file. */
>  void replay_check_error(void);
>  
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>