Re: [Qemu-devel] [PATCH 4/9] runstate_set(): Check for valid transitions

[Blue Swirl]

On Wed, Sep 14, 2011 at 3:06 AM, Luiz Capitulino <address@hidden> wrote:
> On Fri,  9 Sep 2011 17:25:41 -0300
> Luiz Capitulino <address@hidden> wrote:
>
>> This commit could have been folded with the previous one, however
>> doing it separately will allow for easy bisect and revert if needed.
>>
>> Checking and testing all valid transitions wasn't trivial, chances
>> are this will need broader testing to become more stable.
>>
>> This is a transition table as suggested by Lluís Vilanova.
>>
>> Signed-off-by: Luiz Capitulino <address@hidden>
>
> Would be nice to get a reviewed-by for this patch, as it wasn't trivial
> to get it right and tested...
>
>> ---
>>  sysemu.h |    1 +
>>  vl.c     |   74 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  2 files changed, 74 insertions(+), 1 deletions(-)
>>
>> diff --git a/sysemu.h b/sysemu.h
>> index 19088aa..a01ddac 100644
>> --- a/sysemu.h
>> +++ b/sysemu.h
>> @@ -36,6 +36,7 @@ extern uint8_t qemu_uuid[];
>>  int qemu_uuid_parse(const char *str, uint8_t *uuid);
>>  #define UUID_FMT 
>> "%02hhx%02hhx%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
>>
>> +void runstate_init(void);
>>  bool runstate_check(RunState state);
>>  void runstate_set(RunState new_state);
>>  typedef struct vm_change_state_entry VMChangeStateEntry;
>> diff --git a/vl.c b/vl.c
>> index 9926d2a..4a8edc7 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -327,14 +327,84 @@ static int default_driver_check(QemuOpts *opts, void 
>> *opaque)
>>
>>  static RunState current_run_state = RSTATE_NO_STATE;
>>
>> +typedef struct {
>> +    RunState from;
>> +    RunState to;
>> +} RunStateTransition;
>> +
>> +static const RunStateTransition runstate_transitions_def[] = {
>> +    /*     from      ->     to      */
>> +    { RSTATE_NO_STATE, RSTATE_RUNNING },
>> +    { RSTATE_NO_STATE, RSTATE_IN_MIGRATE },
>> +    { RSTATE_NO_STATE, RSTATE_PRE_LAUNCH },
>> +
>> +    { RSTATE_DEBUG, RSTATE_RUNNING },
>> +
>> +    { RSTATE_IN_MIGRATE, RSTATE_RUNNING },
>> +    { RSTATE_IN_MIGRATE, RSTATE_PRE_LAUNCH },
>> +
>> +    { RSTATE_PANICKED, RSTATE_PAUSED },
>> +
>> +    { RSTATE_IO_ERROR, RSTATE_RUNNING },
>> +
>> +    { RSTATE_PAUSED, RSTATE_RUNNING },
>> +
>> +    { RSTATE_POST_MIGRATE, RSTATE_RUNNING },
>> +
>> +    { RSTATE_PRE_LAUNCH, RSTATE_RUNNING },
>> +    { RSTATE_PRE_LAUNCH, RSTATE_POST_MIGRATE },
>> +
>> +    { RSTATE_PRE_MIGRATE, RSTATE_RUNNING },
>> +    { RSTATE_PRE_MIGRATE, RSTATE_POST_MIGRATE },
>> +
>> +    { RSTATE_RESTORE, RSTATE_RUNNING },
>> +
>> +    { RSTATE_RUNNING, RSTATE_DEBUG },
>> +    { RSTATE_RUNNING, RSTATE_PANICKED },
>> +    { RSTATE_RUNNING, RSTATE_IO_ERROR },
>> +    { RSTATE_RUNNING, RSTATE_PAUSED },
>> +    { RSTATE_RUNNING, RSTATE_PRE_MIGRATE },
>> +    { RSTATE_RUNNING, RSTATE_RESTORE },
>> +    { RSTATE_RUNNING, RSTATE_SAVEVM },
>> +    { RSTATE_RUNNING, RSTATE_SHUTDOWN },
>> +    { RSTATE_RUNNING, RSTATE_WATCHDOG },
>> +
>> +    { RSTATE_SAVEVM, RSTATE_RUNNING },
>> +
>> +    { RSTATE_SHUTDOWN, RSTATE_PAUSED },
>> +
>> +    { RSTATE_WATCHDOG, RSTATE_RUNNING },
>> +
>> +    { RSTATE_MAX, RSTATE_MAX },

I don't see a state which requires a system_reset to recover, which I
think was the original motivation. Do I miss something?

Otherwise the patch looks fine.

>> +};
>> +
>> +static bool runstate_valid_transitions[RSTATE_MAX][RSTATE_MAX];
>> +
>>  bool runstate_check(RunState state)
>>  {
>>      return current_run_state == state;
>>  }
>>
>> +void runstate_init(void)
>> +{
>> +    const RunStateTransition *p;
>> +
>> +    memset(&runstate_valid_transitions, 0, 
>> sizeof(runstate_valid_transitions));
>> +
>> +    for (p = &runstate_transitions_def[0]; p->from != RSTATE_MAX; p++) {
>> +        runstate_valid_transitions[p->from][p->to] = true;
>> +    }
>> +}
>> +
>> +/* This function will abort() on invalid state transitions */
>>  void runstate_set(RunState new_state)
>>  {
>> -    assert(new_state < RSTATE_MAX);
>> +    if (new_state >= RSTATE_MAX ||
>> +        !runstate_valid_transitions[current_run_state][new_state]) {
>> +        fprintf(stderr, "invalid runstate transition\n");
>> +        abort();
>> +    }
>> +
>>      current_run_state = new_state;
>>  }
>>
>> @@ -2218,6 +2288,8 @@ int main(int argc, char **argv, char **envp)
>>
>>      g_mem_set_vtable(&mem_trace);
>>
>> +    runstate_init();
>> +
>>      init_clocks();
>>
>>      qemu_cache_utils_init(envp);
>
>
>