diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bitmap.h | 44 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 31 |
2 files changed, 54 insertions, 21 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index fb3a9c93ac86..aa4096126553 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -522,17 +522,18 @@ static inline void bitmap_replace(unsigned long *dst, * * (Bits 0, 1, 2, 3, 4, 5 are copied to the bits 0, 1, 4, 8, 9, 12) * - * A more 'visual' description of the operation: - * src: 0000000001011010 - * |||||| - * +------+||||| - * | +----+|||| - * | |+----+||| - * | || +-+|| - * | || | || - * mask: ...v..vv...v..vv - * ...0..11...0..10 - * dst: 0000001100000010 + * A more 'visual' description of the operation:: + * + * src: 0000000001011010 + * |||||| + * +------+||||| + * | +----+|||| + * | |+----+||| + * | || +-+|| + * | || | || + * mask: ...v..vv...v..vv + * ...0..11...0..10 + * dst: 0000001100000010 * * A relationship exists between bitmap_scatter() and bitmap_gather(). * bitmap_gather() can be seen as the 'reverse' bitmap_scatter() operation. @@ -568,16 +569,17 @@ static inline void bitmap_scatter(unsigned long *dst, const unsigned long *src, * * (Bits 0, 1, 4, 8, 9, 12 are copied to the bits 0, 1, 2, 3, 4, 5) * - * A more 'visual' description of the operation: - * mask: ...v..vv...v..vv - * src: 0000001100000010 - * ^ ^^ ^ 0 - * | || | 10 - * | || > 010 - * | |+--> 1010 - * | +--> 11010 - * +----> 011010 - * dst: 0000000000011010 + * A more 'visual' description of the operation:: + * + * mask: ...v..vv...v..vv + * src: 0000001100000010 + * ^ ^^ ^ 0 + * | || | 10 + * | || > 010 + * | |+--> 1010 + * | +--> 11010 + * +----> 011010 + * dst: 0000000000011010 * * A relationship exists between bitmap_gather() and bitmap_scatter(). See * bitmap_scatter() for the bitmap scatter detailed operations. diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 16f519914415..17d7ed5f3ae6 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -247,6 +247,37 @@ do { \ cond_resched(); \ } while (0) +/** + * rcu_softirq_qs_periodic - Report RCU and RCU-Tasks quiescent states + * @old_ts: jiffies at start of processing. + * + * This helper is for long-running softirq handlers, such as NAPI threads in + * networking. The caller should initialize the variable passed in as @old_ts + * at the beginning of the softirq handler. When invoked frequently, this macro + * will invoke rcu_softirq_qs() every 100 milliseconds thereafter, which will + * provide both RCU and RCU-Tasks quiescent states. Note that this macro + * modifies its old_ts argument. + * + * Because regions of code that have disabled softirq act as RCU read-side + * critical sections, this macro should be invoked with softirq (and + * preemption) enabled. + * + * The macro is not needed when CONFIG_PREEMPT_RT is defined. RT kernels would + * have more chance to invoke schedule() calls and provide necessary quiescent + * states. As a contrast, calling cond_resched() only won't achieve the same + * effect because cond_resched() does not provide RCU-Tasks quiescent states. + */ +#define rcu_softirq_qs_periodic(old_ts) \ +do { \ + if (!IS_ENABLED(CONFIG_PREEMPT_RT) && \ + time_after(jiffies, (old_ts) + HZ / 10)) { \ + preempt_disable(); \ + rcu_softirq_qs(); \ + preempt_enable(); \ + (old_ts) = jiffies; \ + } \ +} while (0) + /* * Infrastructure to implement the synchronize_() primitives in * TREE_RCU and rcu_barrier_() primitives in TINY_RCU. |