virtio-rng: fix condition checking on period_ms

The condition checking on vrng->conf.period_ms appears to be wrong, conflicting with the error comment following it.

Signed-off-by Wei Huang <[email protected]>

---
 hw/virtio/virtio-rng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

hw/virtio/virtio-rng.c +0 -0

index 473c044..a06427c 100644

Quoted 14 lines · Wei Huang

The condition checking on vrng->conf.period_ms appears to be wrong, conflicting with the error comment following it.

Signed-off-by Wei Huang <[email protected]>

---
 hw/virtio/virtio-rng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

hw/virtio/virtio-rng.c +0 -0

index 473c044..a06427c 100644

hw/virtio/virtio-rng.c static void virtio_rng_device_realize(DeviceState *dev, Error **errp) · line 155

Quoted 8 lines

hw/virtio/virtio-rng.c +1 -1

@@ -149,7 +149,7 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
     VirtIORNG *vrng = VIRTIO_RNG(dev);
     Error *local_err = NULL;
 
-    if (!vrng->conf.period_ms > 0) {
+    if (!(vrng->conf.period_ms > 0)) {
         error_setg(errp, "'period' parameter expects a positive integer");
         return;
     }

The current condition is absolutely weird, but I think it happens to work correctly:

Period_ms has type uint32_t. If it is positive, then !period_ms is zero. 0>0 is false, hence the error message is not printed.

If period_ms is zero, then !period_ms is 1. 1>0 is true, hence the error message is printed.

I would rewrite the check as

    if (vrng->conf.period_ms == 0) {
        error_setg(...)

Quoted 33 lines · Laszlo Ersek

Quoted 14 lines · Wei Huang

The condition checking on vrng->conf.period_ms appears to be wrong, conflicting with the error comment following it.

Signed-off-by Wei Huang <[email protected]>

---
 hw/virtio/virtio-rng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

hw/virtio/virtio-rng.c +0 -0

index 473c044..a06427c 100644

hw/virtio/virtio-rng.c static void virtio_rng_device_realize(DeviceState *dev, Error **errp) · line 155

Quoted 8 lines

hw/virtio/virtio-rng.c +1 -1

@@ -149,7 +149,7 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
     VirtIORNG *vrng = VIRTIO_RNG(dev);
     Error *local_err = NULL;
 
-    if (!vrng->conf.period_ms > 0) {
+    if (!(vrng->conf.period_ms > 0)) {
         error_setg(errp, "'period' parameter expects a positive integer");
         return;
     }

The current condition is absolutely weird, but I think it happens to work correctly:

Period_ms has type uint32_t. If it is positive, then !period_ms is zero. 0>0 is false, hence the error message is not printed.

If period_ms is zero, then !period_ms is 1. 1>0 is true, hence the error message is printed.

Quoted 4 lines

I would rewrite the check as

    if (vrng->conf.period_ms == 0) {
        error_setg(...)

... actually, what the heck are you looking at? :) This has been fixed up in:

commit a3a292c420d2fec3c07a7ca56fbb064cd57a298a

Author: Amit Shah <[email protected]>
Date:   Thu Dec 11 13:17:42 2014 +0530

virtio-rng: fix check for period_ms validity

Thanks
Laszlo