Documentation/locking/seqlock.rst

8 Sequence counters are a reader-writer consistency mechanism with
9 lockless readers (read-only retry loops), and no writer starvation. They
10 are used for data that's rarely written to (e.g. system time), where the
11 reader wants a consistent set of information and is willing to retry if
19 the reader must retry.
30 interrupted writer. If that reader belongs to a real-time scheduling
53 requirements of writer serialization and non-preemptibility, use
76 	/* ... [[write-side critical section]] ... */
85 		/* ... [[read-side critical section]] ... */
93 -----------------------------------------------------------------
96 sections must be serialized and non-preemptible. This variant of
98 initialization time, which enables lockdep to validate that the write
112   - ``seqcount_spinlock_t``
113   - ``seqcount_raw_spinlock_t``
114   - ``seqcount_rwlock_t``
115   - ``seqcount_mutex_t``
116   - ``seqcount_ww_mutex_t``
145 ----------------------------------------------
165 embedded spinlock for writer serialization and non-preemptibility.
189 	/* ... [[write-side critical section]] ... */
196    retry if a writer is in progress by detecting change in the sequence
202 		/* ... [[read-side critical section]] ... */
213 	/* ... [[read-side critical section]] ... */
219    starvation (too much retry loops) in case of a sharp spike in write
223    full locking read and no retry loop is necessary::
230 		/* ... [[read-side critical section]] ... */
239 .. kernel-doc:: include/linux/seqlock.h