[PATCH tip/core/rcu 18/41] tracing: Replace synchronize_sched() and call_rcu_sched()

Paul E. McKenney
2018-11-11T19:44:28Z

Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can
be replaced by synchronize_rcu(). Similarly, call_rcu_sched() can be
replaced by call_rcu(). This commit therefore makes these changes.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <linux-kernel@vger.kernel.org>
---
include/linux/tracepoint.h | 2 +-
kernel/trace/ftrace.c | 24 ++++++++++++------------
kernel/trace/ring_buffer.c | 12 ++++++------
kernel/trace/trace.c | 10 +++++-----
kernel/trace/trace_events_filter.c | 4 ++--
kernel/trace/trace_kprobe.c | 2 +-
kernel/tracepoint.c | 4 ++--
7 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 538ba1a58f5b..432080b59c26 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -82,7 +82,7 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb)
static inline void tracepoint_synchronize_unregister(void)
{
synchronize_srcu(&tracepoint_srcu);
- synchronize_sched();
+ synchronize_rcu();
}
#else
static inline void tracepoint_synchronize_unregister(void)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f536f601bd46..5b4f73e4fd56 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -173,7 +173,7 @@ static void ftrace_sync(struct work_struct *work)
{
/*
* This function is just a stub to implement a hard force
- * of synchronize_sched(). This requires synchronizing
+ * of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle.
*
* Yes, function tracing is rude.
@@ -934,7 +934,7 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
ftrace_profile_enabled = 0;
/*
* unregister_ftrace_profiler calls stop_machine
- * so this acts like an synchronize_sched.
+ * so this acts like an synchronize_rcu.
*/
unregister_ftrace_profiler();
}
@@ -1086,7 +1086,7 @@ struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)

/*
* Some of the ops may be dynamically allocated,
- * they are freed after a synchronize_sched().
+ * they are freed after a synchronize_rcu().
*/
preempt_disable_notrace();

@@ -1286,7 +1286,7 @@ static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
{
if (!hash || hash == EMPTY_HASH)
return;
- call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
+ call_rcu(&hash->rcu, __free_ftrace_hash_rcu);
}

void ftrace_free_filter(struct ftrace_ops *ops)
@@ -1501,7 +1501,7 @@ static bool hash_contains_ip(unsigned long ip,
* the ip is not in the ops->notrace_hash.
*
* This needs to be called with preemption disabled as
- * the hashes are freed with call_rcu_sched().
+ * the hashes are freed with call_rcu().
*/
static int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
@@ -4496,7 +4496,7 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
if (ftrace_enabled && !ftrace_hash_empty(hash))
ftrace_run_modify_code(&probe->ops, FTRACE_UPDATE_CALLS,
&old_hash_ops);
- synchronize_sched();
+ synchronize_rcu();

hlist_for_each_entry_safe(entry, tmp, &hhd, hlist) {
hlist_del(&entry->hlist);
@@ -5314,7 +5314,7 @@ ftrace_graph_release(struct inode *inode, struct file *file)
mutex_unlock(&graph_lock);

/* Wait till all users are no longer using the old hash */
- synchronize_sched();
+ synchronize_rcu();

free_ftrace_hash(old_hash);
}
@@ -5707,7 +5707,7 @@ void ftrace_release_mod(struct module *mod)
list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
if (mod_map->mod == mod) {
list_del_rcu(&mod_map->list);
- call_rcu_sched(&mod_map->rcu, ftrace_free_mod_map);
+ call_rcu(&mod_map->rcu, ftrace_free_mod_map);
break;
}
}
@@ -5927,7 +5927,7 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
struct ftrace_mod_map *mod_map;
const char *ret = NULL;

- /* mod_map is freed via call_rcu_sched() */
+ /* mod_map is freed via call_rcu() */
preempt_disable();
list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
@@ -6262,7 +6262,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,

/*
* Some of the ops may be dynamically allocated,
- * they must be freed after a synchronize_sched().
+ * they must be freed after a synchronize_rcu().
*/
preempt_disable_notrace();

@@ -6433,7 +6433,7 @@ static void clear_ftrace_pids(struct trace_array *tr)
rcu_assign_pointer(tr->function_pids, NULL);

/* Wait till all users are no longer using pid filtering */
- synchronize_sched();
+ synchronize_rcu();

trace_free_pid_list(pid_list);
}
@@ -6580,7 +6580,7 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf,
rcu_assign_pointer(tr->function_pids, pid_list);

if (filtered_pids) {
- synchronize_sched();
+ synchronize_rcu();
trace_free_pid_list(filtered_pids);
} else if (pid_list) {
/* Register a probe to set whether to ignore the tracing of a task */
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 65bd4616220d..4f3247a53259 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1834,7 +1834,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
* There could have been a race between checking
* record_disable and incrementing it.
*/
- synchronize_sched();
+ synchronize_rcu();
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
rb_check_pages(cpu_buffer);
@@ -3151,7 +3151,7 @@ static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
- * The caller should call synchronize_sched() after this.
+ * The caller should call synchronize_rcu() after this.
*/
void ring_buffer_record_disable(struct ring_buffer *buffer)
{
@@ -3253,7 +3253,7 @@ bool ring_buffer_record_is_set_on(struct ring_buffer *buffer)
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
- * The caller should call synchronize_sched() after this.
+ * The caller should call synchronize_rcu() after this.
*/
void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu)
{
@@ -4191,7 +4191,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_read_prepare);
void
ring_buffer_read_prepare_sync(void)
{
- synchronize_sched();
+ synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync);

@@ -4363,7 +4363,7 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
atomic_inc(&cpu_buffer->record_disabled);

/* Make sure all commits have finished */
- synchronize_sched();
+ synchronize_rcu();

raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);

@@ -4496,7 +4496,7 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
goto out;

/*
- * We can't do a synchronize_sched here because this
+ * We can't do a synchronize_rcu here because this
* function can be called in atomic context.
* Normally this will be called from the same CPU as cpu.
* If not it's up to the caller to protect this.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ff1c4b20cd0a..51612b4a603f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1681,7 +1681,7 @@ void tracing_reset(struct trace_buffer *buf, int cpu)
ring_buffer_record_disable(buffer);

/* Make sure all commits have finished */
- synchronize_sched();
+ synchronize_rcu();
ring_buffer_reset_cpu(buffer, cpu);

ring_buffer_record_enable(buffer);
@@ -1698,7 +1698,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf)
ring_buffer_record_disable(buffer);

/* Make sure all commits have finished */
- synchronize_sched();
+ synchronize_rcu();

buf->time_start = buffer_ftrace_now(buf, buf->cpu);

@@ -2250,7 +2250,7 @@ void trace_buffered_event_disable(void)
preempt_enable();

/* Wait for all current users to finish */
- synchronize_sched();
+ synchronize_rcu();

for_each_tracing_cpu(cpu) {
free_page((unsigned long)per_cpu(trace_buffered_event, cpu));
@@ -5398,7 +5398,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
if (tr->current_trace->reset)
tr->current_trace->reset(tr);

- /* Current trace needs to be nop_trace before synchronize_sched */
+ /* Current trace needs to be nop_trace before synchronize_rcu */
tr->current_trace = &nop_trace;

#ifdef CONFIG_TRACER_MAX_TRACE
@@ -5412,7 +5412,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
* The update_max_tr is called from interrupts disabled
* so a synchronized_sched() is sufficient.
*/
- synchronize_sched();
+ synchronize_rcu();
free_snapshot(tr);
}
#endif
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 84a65173b1e9..35f3aa55be85 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1614,7 +1614,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,

/*
* The calls can still be using the old filters.
- * Do a synchronize_sched() and to ensure all calls are
+ * Do a synchronize_rcu() and to ensure all calls are
* done with them before we free them.
*/
tracepoint_synchronize_unregister();
@@ -1845,7 +1845,7 @@ int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
if (filter) {
/*
* No event actually uses the system filter
- * we can free it without synchronize_sched().
+ * we can free it without synchronize_rcu().
*/
__free_filter(system->filter);
system->filter = filter;
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index fec67188c4d2..adc153ab51c0 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -333,7 +333,7 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
* event_call related objects, which will be accessed in
* the kprobe_trace_func/kretprobe_trace_func.
*/
- synchronize_sched();
+ synchronize_rcu();
kfree(link); /* Ignored if link == NULL */
}

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index a3be42304485..46f2ab1e08a9 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -92,7 +92,7 @@ static __init int release_early_probes(void)
while (early_probes) {
tmp = early_probes;
early_probes = tmp->next;
- call_rcu_sched(tmp, rcu_free_old_probes);
+ call_rcu(tmp, rcu_free_old_probes);
}

return 0;
@@ -123,7 +123,7 @@ static inline void release_probes(struct tracepoint_func *old)
* cover both cases. So let us chain the SRCU and sched RCU
* callbacks to wait for both grace periods.
*/
- call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
+ call_rcu(&tp_probes->rcu, rcu_free_old_probes);
}
}

--
2.17.1