[Xen-devel] [PATCH 1/3] xen: drop in_atomic()

[Juergen Gross <jgross@xxxxxxxx>]

Currently there is only one user of in_atomic(), and that is in an
#ifdef 0 section. This has been so since Xen 4.1, so chances are
rather slim we suddenly want to enable it again.

Dropping in_atomic() will remove the last user of preempt_count()
in non-debug builds enabling further optimizations.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c    | 16 ----------------
 xen/common/preempt.c      |  5 -----
 xen/include/xen/preempt.h |  2 --
 3 files changed, 23 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 8993c2aa57..7b36765b97 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3185,22 +3185,6 @@ static enum hvm_translation_result __hvm_copy(
 
     ASSERT(is_hvm_vcpu(v));
 
-    /*
-     * XXX Disable for 4.1.0: PV-on-HVM drivers will do grant-table ops
-     * such as query_size. Grant-table code currently does copy_to/from_guest
-     * accesses under the big per-domain lock, which this test would disallow.
-     * The test is not needed until we implement sleeping-on-waitqueue when
-     * we access a paged-out frame, and that's post 4.1.0 now.
-     */
-#if 0
-    /*
-     * If the required guest memory is paged out, this function may sleep.
-     * Hence we bail immediately if called from atomic context.
-     */
-    if ( in_atomic() )
-        return HVMTRANS_unhandleable;
-#endif
-
     while ( todo > 0 )
     {
         enum hvm_translation_result res;
diff --git a/xen/common/preempt.c b/xen/common/preempt.c
index 3b4178fd44..20913e20d3 100644
--- a/xen/common/preempt.c
+++ b/xen/common/preempt.c
@@ -25,11 +25,6 @@
 
 DEFINE_PER_CPU(unsigned int, __preempt_count);
 
-bool_t in_atomic(void)
-{
-    return preempt_count() || in_irq() || !local_irq_is_enabled();
-}
-
 #ifndef NDEBUG
 void ASSERT_NOT_IN_ATOMIC(void)
 {
diff --git a/xen/include/xen/preempt.h b/xen/include/xen/preempt.h
index bef83135a1..f715ca09bc 100644
--- a/xen/include/xen/preempt.h
+++ b/xen/include/xen/preempt.h
@@ -26,8 +26,6 @@ DECLARE_PER_CPU(unsigned int, __preempt_count);
     preempt_count()--;                          \
 } while (0)
 
-bool_t in_atomic(void);
-
 #ifndef NDEBUG
 void ASSERT_NOT_IN_ATOMIC(void);
 #else
-- 
2.16.4


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