[Qemu-devel] [RFC PATCH] migration: do not use atomic__nocheck() functions directly

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

(incorrectly use in 3be98be4e9f)

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
currently on ppc32 the linking fails:

  CC      migration/postcopy-ram.o
...
  LINK    microblaze-softmmu/qemu-system-microblaze
../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
migration/postcopy-ram.c:717: undefined reference to `__atomic_fetch_add_8'
migration/postcopy-ram.c:738: undefined reference to `__atomic_fetch_add_8'
../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
migration/postcopy-ram.c:651: undefined reference to `__atomic_exchange_8'
migration/postcopy-ram.c:652: undefined reference to `__atomic_exchange_8'
migration/postcopy-ram.c:661: undefined reference to `__atomic_exchange_8'
collect2: error: ld returned 1 exit status
Makefile:193: recipe for target 'qemu-system-microblaze' failed
make[1]: *** [qemu-system-microblaze] Error 1

with this patch the compilation fails:

  CC      migration/postcopy-ram.o
In file included from include/qemu/osdep.h:36:0,
                 from migration/postcopy-ram.c:19:
migration/postcopy-ram.c: In function 'mark_postcopy_blocktime_begin':
include/qemu/compiler.h:86:30: error: static assertion failed: "not expecting: sizeof(*&dc->last_begin) > ATOMIC_REG_SIZE"
 #define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
                              ^
include/qemu/atomic.h:183:5: note: in expansion of macro 'QEMU_BUILD_BUG_ON'
     QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE);      \
     ^
migration/postcopy-ram.c:651:5: note: in expansion of macro 'atomic_xchg'
     atomic_xchg(&dc->last_begin, now_ms);
     ^

 migration/postcopy-ram.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 7814da5b4b..6ecc1aa820 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -648,17 +648,17 @@ static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
         atomic_inc(&dc->smp_cpus_down);
     }
 
-    atomic_xchg__nocheck(&dc->last_begin, now_ms);
-    atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms);
-    atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr);
+    atomic_xchg(&dc->last_begin, now_ms);
+    atomic_xchg(&dc->page_fault_vcpu_time[cpu], now_ms);
+    atomic_xchg(&dc->vcpu_addr[cpu], addr);
 
     /* check it here, not at the begining of the function,
      * due to, check could accur early than bitmap_set in
      * qemu_ufd_copy_ioctl */
     already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
     if (already_received) {
-        atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0);
-        atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0);
+        atomic_xchg(&dc->vcpu_addr[cpu], 0);
+        atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
         atomic_dec(&dc->smp_cpus_down);
     }
     trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
@@ -719,7 +719,7 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
             read_vcpu_time == 0) {
             continue;
         }
-        atomic_xchg__nocheck(&dc->vcpu_addr[i], 0);
+        atomic_xchg(&dc->vcpu_addr[i], 0);
         vcpu_blocktime = now_ms - read_vcpu_time;
         affected_cpu += 1;
         /* we need to know is that mark_postcopy_end was due to
-- 
2.15.1