Signed-off-by: Junchang Wang <junchangwang@xxxxxxxxx>
---
CodeSamples/defer/route_seqlock.c | 6 +++---
CodeSamples/defer/seqlock.h | 4 ++--
defer/seqlock.tex | 12 ++++++------
3 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/CodeSamples/defer/route_seqlock.c b/CodeSamples/defer/route_seqlock.c
index 633cf05..8224682 100644
--- a/CodeSamples/defer/route_seqlock.c
+++ b/CodeSamples/defer/route_seqlock.c
@@ -47,7 +47,7 @@ retry:
s = read_seqbegin(&sl);
repp = &route_list.re_next;
do {
- rep = ACCESS_ONCE(*repp);
+ rep = READ_ONCE(*repp);
if (rep == NULL) {
if (read_seqretry(&sl, s))
goto retry;
@@ -57,7 +57,7 @@ retry:
/* Advance to next. */
repp = &rep->re_next;
} while (rep->addr != addr);
- if (ACCESS_ONCE(rep->re_freed))
+ if (READ_ONCE(rep->re_freed))
abort();
ret = rep->iface;
if (read_seqretry(&sl, s))
@@ -123,7 +123,7 @@ void route_clear(void)
write_seqlock(&sl);
rep = route_list.re_next;
- ACCESS_ONCE(route_list.re_next) = NULL;
+ WRITE_ONCE(route_list.re_next, NULL);
while (rep != NULL) {
rep1 = rep->re_next;
free(rep);
diff --git a/CodeSamples/defer/seqlock.h b/CodeSamples/defer/seqlock.h
index b210944..c994285 100644
--- a/CodeSamples/defer/seqlock.h
+++ b/CodeSamples/defer/seqlock.h
@@ -38,7 +38,7 @@ static inline unsigned long read_seqbegin(seqlock_t *slp)
{
unsigned long s;
- s = ACCESS_ONCE(slp->seq);
+ s = READ_ONCE(slp->seq);
smp_mb();
return s & ~0x1UL;
}
@@ -48,7 +48,7 @@ static inline int read_seqretry(seqlock_t *slp, unsigned long oldseq)
unsigned long s;
smp_mb();
- s = ACCESS_ONCE(slp->seq);
+ s = READ_ONCE(slp->seq);
return s != oldseq;
}
diff --git a/defer/seqlock.tex b/defer/seqlock.tex
index ba8abfe..cb5e4e6 100644
--- a/defer/seqlock.tex
+++ b/defer/seqlock.tex
@@ -116,7 +116,7 @@ It is also used in pathname traversal to detect concurrent rename operations.
13 {
14 unsigned long s;
15
-16 s = ACCESS_ONCE(slp->seq);
+16 s = READ_ONCE(slp->seq);
17 smp_mb();
18 return s & ~0x1UL;
19 }
@@ -127,7 +127,7 @@ It is also used in pathname traversal to detect concurrent rename operations.
24 unsigned long s;
25
26 smp_mb();
-27 s = ACCESS_ONCE(slp->seq);
+27 s = READ_ONCE(slp->seq);
28 return s != oldseq;
29 }
30
@@ -211,11 +211,11 @@ in other words, that there has been no writer, and returns true if so.
In older versions of the Linux kernel, no.
In very new versions of the Linux kernel, line~16 could use
- \co{smp_load_acquire()} instead of \co{ACCESS_ONCE()}, which
+ \co{smp_load_acquire()} instead of \co{READ_ONCE()}, which
in turn would allow the \co{smp_mb()} on line~17 to be dropped.
Similarly, line~41 could use an \co{smp_store_release()}, for
example, as follows: \\
- \co{smp_store_release(&slp->seq, ACCESS_ONCE(slp->seq) + 1);} \\
+ \co{smp_store_release(&slp->seq, READ_ONCE(slp->seq) + 1);} \\
This would allow the \co{smp_mb()} on line~40 to be dropped.
} \QuickQuizEnd
@@ -310,7 +310,7 @@ increment of the sequence number on line~44, then releases the lock.
18 s = read_seqbegin(&sl);
19 repp = &route_list.re_next;
20 do {
-21 rep = ACCESS_ONCE(*repp);
+21 rep = READ_ONCE(*repp);
22 if (rep == NULL) {
23 if (read_seqretry(&sl, s))
24 goto retry;
@@ -318,7 +318,7 @@ increment of the sequence number on line~44, then releases the lock.
26 }
27 repp = &rep->re_next;
28 } while (rep->addr != addr);
-29 if (ACCESS_ONCE(rep->re_freed))
+29 if (READ_ONCE(rep->re_freed))
30 abort();
31 ret = rep->iface;
32 if (read_seqretry(&sl, s))
--
2.7.4
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