qemu/atomic.h: rename atomic_ to qatomic_

clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when a QEMU code calls these functions in a source file
that also included <stdatomic.h> via a system header file:

  $ CC=clang CXX=clang++ ./configure ... && make
  ../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid)

Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h
and <stdatomic.h> can co-exist. I checked /usr/include on my machine and
searched GitHub for existing "qatomic_" users but there seem to be none.

This patch was generated using:

  $ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \
    sort -u >/tmp/changed_identifiers
  $ for identifier in $(</tmp/changed_identifiers); do
        sed -i "s%\<$identifier\>%q$identifier%g" \
            $(git grep -I -l "\<$identifier\>")
    done

I manually fixed line-wrap issues and misaligned rST tables.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923105646.47864-1-stefanha@redhat.com>

hw/virtio/vhost.c

@@ -90,7 +90,7 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
         }
         /* Data must be read atomically. We don't really need barrier semantics
          * but it's easier to use atomic_* than roll our own. */
-        log = atomic_xchg(from, 0);
+        log = qatomic_xchg(from, 0);
         while (log) {
             int bit = ctzl(log);
             hwaddr page_addr;

hw/virtio/virtio-mmio.c

@@ -179,7 +179,7 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size)
         }
         return proxy->vqs[vdev->queue_sel].enabled;
     case VIRTIO_MMIO_INTERRUPT_STATUS:
-        return atomic_read(&vdev->isr);
+        return qatomic_read(&vdev->isr);
     case VIRTIO_MMIO_STATUS:
         return vdev->status;
     case VIRTIO_MMIO_CONFIG_GENERATION:
@@ -370,7 +370,7 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value,
         }
         break;
     case VIRTIO_MMIO_INTERRUPT_ACK:
-        atomic_and(&vdev->isr, ~value);
+        qatomic_and(&vdev->isr, ~value);
         virtio_update_irq(vdev);
         break;
     case VIRTIO_MMIO_STATUS:
@@ -496,7 +496,7 @@ static void virtio_mmio_update_irq(DeviceState *opaque, uint16_t vector)
     if (!vdev) {
         return;
     }
-    level = (atomic_read(&vdev->isr) != 0);
+    level = (qatomic_read(&vdev->isr) != 0);
     trace_virtio_mmio_setting_irq(level);
     qemu_set_irq(proxy->irq, level);
 }

hw/virtio/virtio-pci.c

@@ -72,7 +72,7 @@ static void virtio_pci_notify(DeviceState *d, uint16_t vector)
         msix_notify(&proxy->pci_dev, vector);
     else {
         VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-        pci_set_irq(&proxy->pci_dev, atomic_read(&vdev->isr) & 1);
+        pci_set_irq(&proxy->pci_dev, qatomic_read(&vdev->isr) & 1);
     }
 }
 
@@ -398,7 +398,7 @@ static uint32_t virtio_ioport_read(VirtIOPCIProxy *proxy, uint32_t addr)
         break;
     case VIRTIO_PCI_ISR:
         /* reading from the ISR also clears it. */
-        ret = atomic_xchg(&vdev->isr, 0);
+        ret = qatomic_xchg(&vdev->isr, 0);
         pci_irq_deassert(&proxy->pci_dev);
         break;
     case VIRTIO_MSI_CONFIG_VECTOR:
@@ -1362,7 +1362,7 @@ static uint64_t virtio_pci_isr_read(void *opaque, hwaddr addr,
 {
     VirtIOPCIProxy *proxy = opaque;
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    uint64_t val = atomic_xchg(&vdev->isr, 0);
+    uint64_t val = qatomic_xchg(&vdev->isr, 0);
     pci_irq_deassert(&proxy->pci_dev);
 
     return val;

hw/virtio/virtio.c

@@ -149,8 +149,8 @@ static void virtio_virtqueue_reset_region_cache(struct VirtQueue *vq)
 {
     VRingMemoryRegionCaches *caches;
 
-    caches = atomic_read(&vq->vring.caches);
-    atomic_rcu_set(&vq->vring.caches, NULL);
+    caches = qatomic_read(&vq->vring.caches);
+    qatomic_rcu_set(&vq->vring.caches, NULL);
     if (caches) {
         call_rcu(caches, virtio_free_region_cache, rcu);
     }
@@ -197,7 +197,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
         goto err_avail;
     }
 
-    atomic_rcu_set(&vq->vring.caches, new);
+    qatomic_rcu_set(&vq->vring.caches, new);
     if (old) {
         call_rcu(old, virtio_free_region_cache, rcu);
     }
@@ -283,7 +283,7 @@ static void vring_packed_flags_write(VirtIODevice *vdev,
 /* Called within rcu_read_lock().  */
 static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
 {
-    return atomic_rcu_read(&vq->vring.caches);
+    return qatomic_rcu_read(&vq->vring.caches);
 }
 
 /* Called within rcu_read_lock().  */
@@ -2007,7 +2007,7 @@ void virtio_reset(void *opaque)
     vdev->queue_sel = 0;
     vdev->status = 0;
     vdev->disabled = false;
-    atomic_set(&vdev->isr, 0);
+    qatomic_set(&vdev->isr, 0);
     vdev->config_vector = VIRTIO_NO_VECTOR;
     virtio_notify_vector(vdev, vdev->config_vector);
 
@@ -2439,13 +2439,13 @@ void virtio_del_queue(VirtIODevice *vdev, int n)
 
 static void virtio_set_isr(VirtIODevice *vdev, int value)
 {
-    uint8_t old = atomic_read(&vdev->isr);
+    uint8_t old = qatomic_read(&vdev->isr);
 
     /* Do not write ISR if it does not change, so that its cacheline remains
      * shared in the common case where the guest does not read it.
      */
     if ((old & value) != value) {
-        atomic_or(&vdev->isr, value);
+        qatomic_or(&vdev->isr, value);
     }
 }
 
@@ -3254,7 +3254,7 @@ void virtio_init(VirtIODevice *vdev, const char *name,
     vdev->started = false;
     vdev->device_id = device_id;
     vdev->status = 0;
-    atomic_set(&vdev->isr, 0);
+    qatomic_set(&vdev->isr, 0);
     vdev->queue_sel = 0;
     vdev->config_vector = VIRTIO_NO_VECTOR;
     vdev->vq = g_malloc0(sizeof(VirtQueue) * VIRTIO_QUEUE_MAX);