updated alarmtest

1 files changed, 6 insertions, 3 deletions

diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 563532e..f192832 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -34,7 +34,8 @@ acquire(struct spinlock *lk)
 
   // Tell the C compiler and the processor to not move loads or stores
   // past this point, to ensure that the critical section's memory
-  // references happen after the lock is acquired.
+  // references happen strictly after the lock is acquired.
+  // On RISC-V, this emits a fence instruction.
   __sync_synchronize();
 
   // Record info about lock acquisition for holding() and debugging.
@@ -52,8 +53,10 @@ release(struct spinlock *lk)
 
   // Tell the C compiler and the CPU to not move loads or stores
   // past this point, to ensure that all the stores in the critical
-  // section are visible to other CPUs before the lock is released.
-  // On RISC-V, this turns into a fence instruction.
+  // section are visible to other CPUs before the lock is released,
+  // and that loads in the critical section occur strictly before
+  // the lock is released.
+  // On RISC-V, this emits a fence instruction.
   __sync_synchronize();
 
   // Release the lock, equivalent to lk->locked = 0.