diff options
Diffstat (limited to 'kernel/spinlock.c')
| -rw-r--r-- | kernel/spinlock.c | 9 |
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. |