[Xen-devel] [PATCH 5/5] xen: use masking operation instead of test_bit for MCSF bits

[Juergen Gross <jgross@xxxxxxxx>]

Use a bit mask for testing of a set bit instead of test_bit in case no
atomic operation is needed, as this will lead to smaller and more
effective code.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/arch/x86/domain.c           | 8 ++++----
 xen/arch/x86/x86_64/compat/mm.c | 4 ++--
 xen/common/multicall.c          | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 4e96f6c..7ca9b93 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1750,7 +1750,7 @@ void hypercall_cancel_continuation(void)
     struct cpu_user_regs *regs = guest_cpu_user_regs();
     struct mc_state *mcs = &current->mc_state;
 
-    if ( test_bit(_MCSF_in_multicall, &mcs->flags) )
+    if ( mcs->flags & MCSF_in_multicall )
     {
         __clear_bit(_MCSF_call_preempted, &mcs->flags);
     }
@@ -1774,7 +1774,7 @@ unsigned long hypercall_create_continuation(
 
     va_start(args, format);
 
-    if ( test_bit(_MCSF_in_multicall, &mcs->flags) )
+    if ( mcs->flags & MCSF_in_multicall )
     {
         __set_bit(_MCSF_call_preempted, &mcs->flags);
 
@@ -1852,9 +1852,9 @@ int hypercall_xlat_continuation(unsigned int *id, 
unsigned int nr,
 
     va_start(args, mask);
 
-    if ( test_bit(_MCSF_in_multicall, &mcs->flags) )
+    if ( mcs->flags & MCSF_in_multicall )
     {
-        if ( !test_bit(_MCSF_call_preempted, &mcs->flags) )
+        if ( !(mcs->flags & MCSF_call_preempted) )
         {
             va_end(args);
             return 0;
diff --git a/xen/arch/x86/x86_64/compat/mm.c b/xen/arch/x86/x86_64/compat/mm.c
index d034bd0..178e42d 100644
--- a/xen/arch/x86/x86_64/compat/mm.c
+++ b/xen/arch/x86/x86_64/compat/mm.c
@@ -324,7 +324,7 @@ int 
compat_mmuext_op(XEN_GUEST_HANDLE_PARAM(mmuext_op_compat_t) cmp_uops,
             {
                 struct cpu_user_regs *regs = guest_cpu_user_regs();
                 struct mc_state *mcs = &current->mc_state;
-                unsigned int arg1 = !test_bit(_MCSF_in_multicall, &mcs->flags)
+                unsigned int arg1 = !(mcs->flags & MCSF_in_multicall)
                                     ? regs->ecx
                                     : mcs->call.args[1];
                 unsigned int left = arg1 & ~MMU_UPDATE_PREEMPTED;
@@ -338,7 +338,7 @@ int 
compat_mmuext_op(XEN_GUEST_HANDLE_PARAM(mmuext_op_compat_t) cmp_uops,
                 {
                     BUG_ON(!hypercall_xlat_continuation(&left, 4, 0x01, 
nat_ops,
                                                         cmp_uops));
-                    if ( !test_bit(_MCSF_in_multicall, &mcs->flags) )
+                    if ( !(mcs->flags & MCSF_in_multicall) )
                         regs->_ecx += count - i;
                     else
                         mcs->compat_call.args[1] += count - i;
diff --git a/xen/common/multicall.c b/xen/common/multicall.c
index fa9d910..21661ee 100644
--- a/xen/common/multicall.c
+++ b/xen/common/multicall.c
@@ -79,7 +79,7 @@ do_multicall(
 
         if ( unlikely(__copy_field_to_guest(call_list, &mcs->call, result)) )
             rc = -EFAULT;
-        else if ( test_bit(_MCSF_call_preempted, &mcs->flags) )
+        else if ( mcs->flags & MCSF_call_preempted )
         {
             /* Translate sub-call continuation to guest layout */
             xlat_multicall_entry(mcs);
-- 
2.1.4


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