Re: [PATCH 2/2] hw/timer/slavio_timer.c: Switch to transaction-based ptimer API

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Peter,

On 10/17/19 3:23 PM, Peter Maydell wrote:
> Switch the slavio_timer code away from bottom-half based ptimers to
> the new transaction-based ptimer API.  This just requires adding
> begin/commit calls around the various places that modify the ptimer
> state, and using the new ptimer_init() function to create the timer.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/timer/slavio_timer.c | 20 ++++++++++++++++----
>   1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/timer/slavio_timer.c b/hw/timer/slavio_timer.c
> index 692d213897d..0e2efe6fe89 100644
> --- a/hw/timer/slavio_timer.c
> +++ b/hw/timer/slavio_timer.c
> @@ -30,7 +30,6 @@
>   #include "hw/sysbus.h"
>   #include "migration/vmstate.h"
>   #include "trace.h"
> -#include "qemu/main-loop.h"
>   #include "qemu/module.h"
>   
>   /*
> @@ -213,6 +212,7 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>       saddr = addr >> 2;
>       switch (saddr) {
>       case TIMER_LIMIT:
> +        ptimer_transaction_begin(t->timer);
>           if (slavio_timer_is_user(tc)) {
>               uint64_t count;


This part is odd since there is a check on t->timer != NULL later, and 
ptimer_transaction_commit() can't take NULL.

This won't happen if you restrict to ptimer_* calls:

-- >8 --
@@ -222,18 +222,22 @@ static void slavio_timer_mem_writel(void *opaque, 
hwaddr addr,
              t->reached = 0;
              count = ((uint64_t)t->counthigh << 32) | t->count;
              trace_slavio_timer_mem_writel_limit(timer_index, count);
+            ptimer_transaction_begin(t->timer);
              ptimer_set_count(t->timer, LIMIT_TO_PERIODS(t->limit - 
count));
+            ptimer_transaction_commit(t->timer);
          } else {
              // set limit, reset counter
              qemu_irq_lower(t->irq);
              t->limit = val & TIMER_MAX_COUNT32;
              if (t->timer) {
+                ptimer_transaction_begin(t->timer);
                  if (t->limit == 0) { /* free-run */
                      ptimer_set_limit(t->timer,
 
LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
                  } else {
                      ptimer_set_limit(t->timer, 
LIMIT_TO_PERIODS(t->limit), 1);
                  }
+                ptimer_transaction_commit(t->timer);
              }
          }
          break;
---

>   
> @@ -236,6 +236,7 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>                   }
>               }
>           }
> +        ptimer_transaction_commit(t->timer);
>           break;
>       case TIMER_COUNTER:
>           if (slavio_timer_is_user(tc)) {
> @@ -247,7 +248,9 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>               t->reached = 0;
>               count = ((uint64_t)t->counthigh) << 32 | t->count;
>               trace_slavio_timer_mem_writel_limit(timer_index, count);
> +            ptimer_transaction_begin(t->timer);
>               ptimer_set_count(t->timer, LIMIT_TO_PERIODS(t->limit - count));
> +            ptimer_transaction_commit(t->timer);
>           } else {
>               trace_slavio_timer_mem_writel_counter_invalid();
>           }
> @@ -255,13 +258,16 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>       case TIMER_COUNTER_NORST:
>           // set limit without resetting counter
>           t->limit = val & TIMER_MAX_COUNT32;
> +        ptimer_transaction_begin(t->timer);
>           if (t->limit == 0) { /* free-run */
>               ptimer_set_limit(t->timer, LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 0);
>           } else {
>               ptimer_set_limit(t->timer, LIMIT_TO_PERIODS(t->limit), 0);
>           }
> +        ptimer_transaction_commit(t->timer);
>           break;
>       case TIMER_STATUS:
> +        ptimer_transaction_begin(t->timer);
>           if (slavio_timer_is_user(tc)) {

I'd move the begin() here.

>               // start/stop user counter
>               if (val & 1) {
> @@ -273,6 +279,7 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>               }
>           }
>           t->run = val & 1;
> +        ptimer_transaction_commit(t->timer);
>           break;
>       case TIMER_MODE:
>           if (timer_index == 0) {
> @@ -282,6 +289,7 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>                   unsigned int processor = 1 << i;
>                   CPUTimerState *curr_timer = &s->cputimer[i + 1];
>   
> +                ptimer_transaction_begin(curr_timer->timer);
>                   // check for a change in timer mode for this processor
>                   if ((val & processor) != (s->cputimer_mode & processor)) {

Ditto, begin() here.

>                       if (val & processor) { // counter -> user timer
> @@ -308,6 +316,7 @@ static void slavio_timer_mem_writel(void *opaque, hwaddr addr,
>                           trace_slavio_timer_mem_writel_mode_counter(timer_index);
>                       }
>                   }
> +                ptimer_transaction_commit(curr_timer->timer);
>               }
>           } else {
>               trace_slavio_timer_mem_writel_mode_invalid();
> @@ -367,10 +376,12 @@ static void slavio_timer_reset(DeviceState *d)
>           curr_timer->count = 0;
>           curr_timer->reached = 0;
>           if (i <= s->num_cpus) {
> +            ptimer_transaction_begin(curr_timer->timer);
>               ptimer_set_limit(curr_timer->timer,
>                                LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
>               ptimer_run(curr_timer->timer, 0);
>               curr_timer->run = 1;
> +            ptimer_transaction_commit(curr_timer->timer);
>           }
>       }
>       s->cputimer_mode = 0;
> @@ -380,7 +391,6 @@ static void slavio_timer_init(Object *obj)
>   {
>       SLAVIO_TIMERState *s = SLAVIO_TIMER(obj);
>       SysBusDevice *dev = SYS_BUS_DEVICE(obj);
> -    QEMUBH *bh;
>       unsigned int i;
>       TimerContext *tc;
>   
> @@ -392,9 +402,11 @@ static void slavio_timer_init(Object *obj)
>           tc->s = s;
>           tc->timer_index = i;
>   
> -        bh = qemu_bh_new(slavio_timer_irq, tc);
> -        s->cputimer[i].timer = ptimer_init_with_bh(bh, PTIMER_POLICY_DEFAULT);
> +        s->cputimer[i].timer = ptimer_init(slavio_timer_irq, tc,
> +                                           PTIMER_POLICY_DEFAULT);
> +        ptimer_transaction_begin(s->cputimer[i].timer);
>           ptimer_set_period(s->cputimer[i].timer, TIMER_PERIOD);
> +        ptimer_transaction_commit(s->cputimer[i].timer);
>   
>           size = i == 0 ? SYS_TIMER_SIZE : CPU_TIMER_SIZE;
>           snprintf(timer_name, sizeof(timer_name), "timer-%i", i);
>