The following commit has been merged into the locking/core branch of tip:
Commit-ID: 93190bc35d6d4364a4d8c38ac8961dabecbff4ed
Gitweb: https://git.kernel.org/tip/93190bc35d6d4364a4d8c38ac8961dabecbff4ed
Author: Marco Elver <elver@xxxxxxxxxx>
AuthorDate: Mon, 04 Nov 2024 16:43:08 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 05 Nov 2024 12:55:35 +01:00
seqlock, treewide: Switch to non-raw seqcount_latch interface
Switch all instrumentable users of the seqcount_latch interface over to
the non-raw interface.
Co-developed-by: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20241104161910.780003-5-elver@xxxxxxxxxx
---
arch/x86/kernel/tsc.c | 5 +++--
include/linux/rbtree_latch.h | 20 +++++++++++---------
kernel/printk/printk.c | 9 +++++----
kernel/time/sched_clock.c | 12 +++++++-----
kernel/time/timekeeping.c | 12 +++++++-----
5 files changed, 33 insertions(+), 25 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index dfe6847..67aeaba 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -174,10 +174,11 @@ static void __set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long ts
c2n = per_cpu_ptr(&cyc2ns, cpu);
- raw_write_seqcount_latch(&c2n->seq);
+ write_seqcount_latch_begin(&c2n->seq);
c2n->data[0] = data;
- raw_write_seqcount_latch(&c2n->seq);
+ write_seqcount_latch(&c2n->seq);
c2n->data[1] = data;
+ write_seqcount_latch_end(&c2n->seq);
}
static void set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long tsc_now)
diff --git a/include/linux/rbtree_latch.h b/include/linux/rbtree_latch.h
index 6a0999c..2f630eb 100644
--- a/include/linux/rbtree_latch.h
+++ b/include/linux/rbtree_latch.h
@@ -14,7 +14,7 @@
*
* If we need to allow unconditional lookups (say as required for NMI context
* usage) we need a more complex setup; this data structure provides this by
- * employing the latch technique -- see @raw_write_seqcount_latch -- to
+ * employing the latch technique -- see @write_seqcount_latch_begin -- to
* implement a latched RB-tree which does allow for unconditional lookups by
* virtue of always having (at least) one stable copy of the tree.
*
@@ -132,7 +132,7 @@ __lt_find(void *key, struct latch_tree_root *ltr, int idx,
* @ops: operators defining the node order
*
* It inserts @node into @root in an ordered fashion such that we can always
- * observe one complete tree. See the comment for raw_write_seqcount_latch().
+ * observe one complete tree. See the comment for write_seqcount_latch_begin().
*
* The inserts use rcu_assign_pointer() to publish the element such that the
* tree structure is stored before we can observe the new @node.
@@ -145,10 +145,11 @@ latch_tree_insert(struct latch_tree_node *node,
struct latch_tree_root *root,
const struct latch_tree_ops *ops)
{
- raw_write_seqcount_latch(&root->seq);
+ write_seqcount_latch_begin(&root->seq);
__lt_insert(node, root, 0, ops->less);
- raw_write_seqcount_latch(&root->seq);
+ write_seqcount_latch(&root->seq);
__lt_insert(node, root, 1, ops->less);
+ write_seqcount_latch_end(&root->seq);
}
/**
@@ -159,7 +160,7 @@ latch_tree_insert(struct latch_tree_node *node,
*
* Removes @node from the trees @root in an ordered fashion such that we can
* always observe one complete tree. See the comment for
- * raw_write_seqcount_latch().
+ * write_seqcount_latch_begin().
*
* It is assumed that @node will observe one RCU quiescent state before being
* reused of freed.
@@ -172,10 +173,11 @@ latch_tree_erase(struct latch_tree_node *node,
struct latch_tree_root *root,
const struct latch_tree_ops *ops)
{
- raw_write_seqcount_latch(&root->seq);
+ write_seqcount_latch_begin(&root->seq);
__lt_erase(node, root, 0);
- raw_write_seqcount_latch(&root->seq);
+ write_seqcount_latch(&root->seq);
__lt_erase(node, root, 1);
+ write_seqcount_latch_end(&root->seq);
}
/**
@@ -204,9 +206,9 @@ latch_tree_find(void *key, struct latch_tree_root *root,
unsigned int seq;
do {
- seq = raw_read_seqcount_latch(&root->seq);
+ seq = read_seqcount_latch(&root->seq);
node = __lt_find(key, root, seq & 1, ops->comp);
- } while (raw_read_seqcount_latch_retry(&root->seq, seq));
+ } while (read_seqcount_latch_retry(&root->seq, seq));
return node;
}
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index beb808f..19911c8 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -560,10 +560,11 @@ bool printk_percpu_data_ready(void)
/* Must be called under syslog_lock. */
static void latched_seq_write(struct latched_seq *ls, u64 val)
{
- raw_write_seqcount_latch(&ls->latch);
+ write_seqcount_latch_begin(&ls->latch);
ls->val[0] = val;
- raw_write_seqcount_latch(&ls->latch);
+ write_seqcount_latch(&ls->latch);
ls->val[1] = val;
+ write_seqcount_latch_end(&ls->latch);
}
/* Can be called from any context. */
@@ -574,10 +575,10 @@ static u64 latched_seq_read_nolock(struct latched_seq *ls)
u64 val;
do {
- seq = raw_read_seqcount_latch(&ls->latch);
+ seq = read_seqcount_latch(&ls->latch);
idx = seq & 0x1;
val = ls->val[idx];
- } while (raw_read_seqcount_latch_retry(&ls->latch, seq));
+ } while (read_seqcount_latch_retry(&ls->latch, seq));
return val;
}
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 29bdf30..fcca4e7 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -71,13 +71,13 @@ static __always_inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
notrace struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
{
- *seq = raw_read_seqcount_latch(&cd.seq);
+ *seq = read_seqcount_latch(&cd.seq);
return cd.read_data + (*seq & 1);
}
notrace int sched_clock_read_retry(unsigned int seq)
{
- return raw_read_seqcount_latch_retry(&cd.seq, seq);
+ return read_seqcount_latch_retry(&cd.seq, seq);
}
static __always_inline unsigned long long __sched_clock(void)
@@ -132,16 +132,18 @@ unsigned long long notrace sched_clock(void)
static void update_clock_read_data(struct clock_read_data *rd)
{
/* steer readers towards the odd copy */
- raw_write_seqcount_latch(&cd.seq);
+ write_seqcount_latch_begin(&cd.seq);
/* now its safe for us to update the normal (even) copy */
cd.read_data[0] = *rd;
/* switch readers back to the even copy */
- raw_write_seqcount_latch(&cd.seq);
+ write_seqcount_latch(&cd.seq);
/* update the backup (odd) copy with the new data */
cd.read_data[1] = *rd;
+
+ write_seqcount_latch_end(&cd.seq);
}
/*
@@ -279,7 +281,7 @@ void __init generic_sched_clock_init(void)
*/
static u64 notrace suspended_sched_clock_read(void)
{
- unsigned int seq = raw_read_seqcount_latch(&cd.seq);
+ unsigned int seq = read_seqcount_latch(&cd.seq);
return cd.read_data[seq & 1].epoch_cyc;
}
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 7e6f409..1875298 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -411,7 +411,7 @@ static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
* We want to use this from any context including NMI and tracing /
* instrumenting the timekeeping code itself.
*
- * Employ the latch technique; see @raw_write_seqcount_latch.
+ * Employ the latch technique; see @write_seqcount_latch.
*
* So if a NMI hits the update of base[0] then it will use base[1]
* which is still consistent. In the worst case this can result is a
@@ -424,16 +424,18 @@ static void update_fast_timekeeper(const struct tk_read_base *tkr,
struct tk_read_base *base = tkf->base;
/* Force readers off to base[1] */
- raw_write_seqcount_latch(&tkf->seq);
+ write_seqcount_latch_begin(&tkf->seq);
/* Update base[0] */
memcpy(base, tkr, sizeof(*base));
/* Force readers back to base[0] */
- raw_write_seqcount_latch(&tkf->seq);
+ write_seqcount_latch(&tkf->seq);
/* Update base[1] */
memcpy(base + 1, base, sizeof(*base));
+
+ write_seqcount_latch_end(&tkf->seq);
}
static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
@@ -443,11 +445,11 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
u64 now;
do {
- seq = raw_read_seqcount_latch(&tkf->seq);
+ seq = read_seqcount_latch(&tkf->seq);
tkr = tkf->base + (seq & 0x01);
now = ktime_to_ns(tkr->base);
now += __timekeeping_get_ns(tkr);
- } while (raw_read_seqcount_latch_retry(&tkf->seq, seq));
+ } while (read_seqcount_latch_retry(&tkf->seq, seq));
return now;
}
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