[Xen-devel] [PATCH for-4.9 v2 2/2] x86/dm: fix clang build

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

The current code in dm_op breaks clang build with:

dm.c:411:21: error: 'break' is bound to loop, GCC binds it to switch 
[-Werror,-Wgcc-compat]
            while ( read_atomic(&p2m->ioreq.entry_count) &&
                    ^
xen/include/asm/atomic.h:53:43: note: expanded from macro 'read_atomic'
    default: x_ = 0; __bad_atomic_size(); break;          \
                                          ^

Move the read_atomic check inside the loop body in order to fix the error.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v1:
 - New in this version.
---
 xen/arch/x86/hvm/dm.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index d72b7bd835..d7aaaf6ff8 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -408,9 +408,16 @@ static int dm_op(domid_t domid,
         {
             struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
-            while ( read_atomic(&p2m->ioreq.entry_count) &&
-                    first_gfn <= p2m->max_mapped_pfn )
+            while ( first_gfn <= p2m->max_mapped_pfn )
             {
+                /*
+                 * NB: read_atomic cannot be used in the loop condition because
+                 * clang complains with: "'break' is bound to loop, GCC binds
+                 * it to switch", so move it inside of the loop instead.
+                 */
+                if ( !read_atomic(&p2m->ioreq.entry_count) )
+                    break;
+
                 /* Iterate p2m table for 256 gfns each time. */
                 p2m_finish_type_change(d, _gfn(first_gfn), 256,
                                        p2m_ioreq_server, p2m_ram_rw);
-- 
2.11.0 (Apple Git-81)


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