turn interrupt::{enable,disable} into compiler barriers

src/interrupt.rs

@@ -45,7 +45,7 @@ pub fn disable() {
             asm!("cpsid i"
                  :
                  :
-                 :
+                 : "memory"
                  : "volatile");
         },
         #[cfg(not(target_arch = "arm"))]
@@ -66,7 +66,7 @@ pub unsafe fn enable() {
             asm!("cpsie i"
                  :
                  :
-                 :
+                 : "memory"
                  : "volatile");
         }
         #[cfg(not(target_arch = "arm"))]
@@ -81,10 +81,6 @@ pub struct CriticalSection {
     _0: (),
 }
 
-macro_rules! barrier {
-    () => { asm!("" ::: "memory" : "volatile") }
-}
-
 /// Execute closure `f` in an interrupt-free context.
 ///
 /// This as also known as a "critical section".
@@ -97,9 +93,7 @@ where
     // disable interrupts
     disable();
 
-    unsafe { barrier!() }
     let r = f(&CriticalSection { _0: () });
-    unsafe { barrier!() }
 
     // If the interrupts were active before our `disable` call, then re-enable
     // them. Otherwise, keep them disabled