Re: [PATCH] replay: fix recursive checkpoints

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/03/21 09:59, Pavel Dovgalyuk wrote:
> Record/replay uses checkpoints to synchronize the execution
> of the threads and timers. Hardware events such as BH are
> processed at the checkpoints too.
> Event processing can cause refreshing the virtual timers
> and calling the icount-related functions, that also use checkpoints.
> This patch prevents recursive processing of such checkpoints,
> because they have their own records in the log and should be
> processed later.
> 
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> ---
>   replay/replay.c |   11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/replay/replay.c b/replay/replay.c
> index c806fec69a..6df2abc18c 100644
> --- a/replay/replay.c
> +++ b/replay/replay.c
> @@ -180,12 +180,13 @@ bool replay_checkpoint(ReplayCheckpoint checkpoint)
>       }
>   
>       if (in_checkpoint) {
> -        /* If we are already in checkpoint, then there is no need
> -           for additional synchronization.
> +        /*
>              Recursion occurs when HW event modifies timers.
> -           Timer modification may invoke the checkpoint and
> -           proceed to recursion. */
> -        return true;
> +           Prevent performing icount warp in this case and
> +           wait for another invocation of the checkpoint.
> +        */
> +        g_assert(replay_mode == REPLAY_MODE_PLAY);
> +        return false;
>       }
>       in_checkpoint = true;
>   
> 

Queued, thanks.

Paolo