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>

1 files changed, 4 insertions, 4 deletions

diff --git a/docs/devel/lockcnt.txt b/docs/devel/lockcnt.txt
index 7c099bc6c8..2d85462fe3 100644
--- a/docs/devel/lockcnt.txt
+++ b/docs/devel/lockcnt.txt
@@ -95,7 +95,7 @@ not just frees, though there could be cases where this is not necessary.
 
 Reads, instead, can be done without taking the mutex, as long as the
 readers and writers use the same macros that are used for RCU, for
-example atomic_rcu_read, atomic_rcu_set, QLIST_FOREACH_RCU, etc.  This is
+example qatomic_rcu_read, qatomic_rcu_set, QLIST_FOREACH_RCU, etc.  This is
 because the reads are done outside a lock and a set or QLIST_INSERT_HEAD
 can happen concurrently with the read.  The RCU API ensures that the
 processor and the compiler see all required memory barriers.
@@ -189,7 +189,7 @@ qemu_lockcnt_lock and qemu_lockcnt_unlock:
     if (!xyz) {
         new_xyz = g_new(XYZ, 1);
         ...
-        atomic_rcu_set(&xyz, new_xyz);
+        qatomic_rcu_set(&xyz, new_xyz);
     }
     qemu_lockcnt_unlock(&xyz_lockcnt);
 
@@ -198,7 +198,7 @@ qemu_lockcnt_dec:
 
     qemu_lockcnt_inc(&xyz_lockcnt);
     if (xyz) {
-        XYZ *p = atomic_rcu_read(&xyz);
+        XYZ *p = qatomic_rcu_read(&xyz);
         ...
         /* Accesses can now be done through "p".  */
     }
@@ -222,7 +222,7 @@ the decrement, the locking and the check on count as follows:
 
     qemu_lockcnt_inc(&xyz_lockcnt);
     if (xyz) {
-        XYZ *p = atomic_rcu_read(&xyz);
+        XYZ *p = qatomic_rcu_read(&xyz);
         ...
         /* Accesses can now be done through "p".  */
     }