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-rw-r--r--include/linux/seqlock.h108
1 files changed, 56 insertions, 52 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 299d68f10325..6c4f68ef1393 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -263,32 +263,32 @@ static inline void raw_write_seqcount_end(seqcount_t *s)
* atomically, avoiding compiler optimizations; b) to document which writes are
* meant to propagate to the reader critical section. This is necessary because
* neither writes before and after the barrier are enclosed in a seq-writer
- * critical section that would ensure readers are aware of ongoing writes.
+ * critical section that would ensure readers are aware of ongoing writes::
*
- * seqcount_t seq;
- * bool X = true, Y = false;
+ * seqcount_t seq;
+ * bool X = true, Y = false;
*
- * void read(void)
- * {
- * bool x, y;
+ * void read(void)
+ * {
+ * bool x, y;
*
- * do {
- * int s = read_seqcount_begin(&seq);
+ * do {
+ * int s = read_seqcount_begin(&seq);
*
- * x = X; y = Y;
+ * x = X; y = Y;
*
- * } while (read_seqcount_retry(&seq, s));
+ * } while (read_seqcount_retry(&seq, s));
*
- * BUG_ON(!x && !y);
+ * BUG_ON(!x && !y);
* }
*
* void write(void)
* {
- * WRITE_ONCE(Y, true);
+ * WRITE_ONCE(Y, true);
*
- * raw_write_seqcount_barrier(seq);
+ * raw_write_seqcount_barrier(seq);
*
- * WRITE_ONCE(X, false);
+ * WRITE_ONCE(X, false);
* }
*/
static inline void raw_write_seqcount_barrier(seqcount_t *s)
@@ -325,64 +325,68 @@ static inline int raw_read_seqcount_latch(seqcount_t *s)
* Very simply put: we first modify one copy and then the other. This ensures
* there is always one copy in a stable state, ready to give us an answer.
*
- * The basic form is a data structure like:
+ * The basic form is a data structure like::
*
- * struct latch_struct {
- * seqcount_t seq;
- * struct data_struct data[2];
- * };
+ * struct latch_struct {
+ * seqcount_t seq;
+ * struct data_struct data[2];
+ * };
*
* Where a modification, which is assumed to be externally serialized, does the
- * following:
+ * following::
*
- * void latch_modify(struct latch_struct *latch, ...)
- * {
- * smp_wmb(); <- Ensure that the last data[1] update is visible
- * latch->seq++;
- * smp_wmb(); <- Ensure that the seqcount update is visible
+ * void latch_modify(struct latch_struct *latch, ...)
+ * {
+ * smp_wmb(); // Ensure that the last data[1] update is visible
+ * latch->seq++;
+ * smp_wmb(); // Ensure that the seqcount update is visible
*
- * modify(latch->data[0], ...);
+ * modify(latch->data[0], ...);
*
- * smp_wmb(); <- Ensure that the data[0] update is visible
- * latch->seq++;
- * smp_wmb(); <- Ensure that the seqcount update is visible
+ * smp_wmb(); // Ensure that the data[0] update is visible
+ * latch->seq++;
+ * smp_wmb(); // Ensure that the seqcount update is visible
*
- * modify(latch->data[1], ...);
- * }
+ * modify(latch->data[1], ...);
+ * }
*
- * The query will have a form like:
+ * The query will have a form like::
*
- * struct entry *latch_query(struct latch_struct *latch, ...)
- * {
- * struct entry *entry;
- * unsigned seq, idx;
+ * struct entry *latch_query(struct latch_struct *latch, ...)
+ * {
+ * struct entry *entry;
+ * unsigned seq, idx;
*
- * do {
- * seq = raw_read_seqcount_latch(&latch->seq);
+ * do {
+ * seq = raw_read_seqcount_latch(&latch->seq);
*
- * idx = seq & 0x01;
- * entry = data_query(latch->data[idx], ...);
+ * idx = seq & 0x01;
+ * entry = data_query(latch->data[idx], ...);
*
- * smp_rmb();
- * } while (seq != latch->seq);
+ * smp_rmb();
+ * } while (seq != latch->seq);
*
- * return entry;
- * }
+ * return entry;
+ * }
*
* So during the modification, queries are first redirected to data[1]. Then we
* modify data[0]. When that is complete, we redirect queries back to data[0]
* and we can modify data[1].
*
- * NOTE: The non-requirement for atomic modifications does _NOT_ include
- * the publishing of new entries in the case where data is a dynamic
- * data structure.
+ * NOTE:
+ *
+ * The non-requirement for atomic modifications does _NOT_ include
+ * the publishing of new entries in the case where data is a dynamic
+ * data structure.
+ *
+ * An iteration might start in data[0] and get suspended long enough
+ * to miss an entire modification sequence, once it resumes it might
+ * observe the new entry.
*
- * An iteration might start in data[0] and get suspended long enough
- * to miss an entire modification sequence, once it resumes it might
- * observe the new entry.
+ * NOTE:
*
- * NOTE: When data is a dynamic data structure; one should use regular RCU
- * patterns to manage the lifetimes of the objects within.
+ * When data is a dynamic data structure; one should use regular RCU
+ * patterns to manage the lifetimes of the objects within.
*/
static inline void raw_write_seqcount_latch(seqcount_t *s)
{