diff options
| -rw-r--r-- | include/linux/srcu.h | 2 | ||||
| -rw-r--r-- | kernel/srcu.c | 19 |
2 files changed, 10 insertions, 11 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index a478c8eb8479..5b49d41868c8 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -35,7 +35,7 @@ struct srcu_struct_array { }; /* Bit definitions for field ->c above and ->snap below. */ -#define SRCU_USAGE_BITS 2 +#define SRCU_USAGE_BITS 1 #define SRCU_REF_MASK (ULONG_MAX >> SRCU_USAGE_BITS) #define SRCU_USAGE_COUNT (SRCU_REF_MASK + 1) diff --git a/kernel/srcu.c b/kernel/srcu.c index 17e95bcc901c..43f1d61e513e 100644 --- a/kernel/srcu.c +++ b/kernel/srcu.c @@ -138,14 +138,14 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx) /* * Now, we check the ->snap array that srcu_readers_active_idx() - * filled in from the per-CPU counter values. Since both - * __srcu_read_lock() and __srcu_read_unlock() increment the - * upper bits of the per-CPU counter, an increment/decrement - * pair will change the value of the counter. Since there is - * only one possible increment, the only way to wrap the counter - * is to have a huge number of counter decrements, which requires - * a huge number of tasks and huge SRCU read-side critical-section - * nesting levels, even on 32-bit systems. + * filled in from the per-CPU counter values. Since + * __srcu_read_lock() increments the upper bits of the per-CPU + * counter, an increment/decrement pair will change the value + * of the counter. Since there is only one possible increment, + * the only way to wrap the counter is to have a huge number of + * counter decrements, which requires a huge number of tasks and + * huge SRCU read-side critical-section nesting levels, even on + * 32-bit systems. * * All of the ways of confusing the readings require that the scan * in srcu_readers_active_idx() see the read-side task's decrement, @@ -234,8 +234,7 @@ void __srcu_read_unlock(struct srcu_struct *sp, int idx) { preempt_disable(); smp_mb(); /* C */ /* Avoid leaking the critical section. */ - ACCESS_ONCE(this_cpu_ptr(sp->per_cpu_ref)->c[idx]) += - SRCU_USAGE_COUNT - 1; + ACCESS_ONCE(this_cpu_ptr(sp->per_cpu_ref)->c[idx]) -= 1; preempt_enable(); } EXPORT_SYMBOL_GPL(__srcu_read_unlock); |
