Update Linux to v5.4.148
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz
Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index bcf4cf2..a42a299 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -243,6 +243,13 @@
* usual consistency guarantee. It is one wmb cheaper, because we can
* collapse the two back-to-back wmb()s.
*
+ * Note that, writes surrounding the barrier should be declared atomic (e.g.
+ * via WRITE_ONCE): a) to ensure the writes become visible to other threads
+ * 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.
+ *
* seqcount_t seq;
* bool X = true, Y = false;
*
@@ -262,11 +269,11 @@
*
* void write(void)
* {
- * Y = true;
+ * WRITE_ONCE(Y, true);
*
* raw_write_seqcount_barrier(seq);
*
- * X = false;
+ * WRITE_ONCE(X, false);
* }
*/
static inline void raw_write_seqcount_barrier(seqcount_t *s)