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Message-ID: <20250802162829.364996738@kernel.org>
Date: Sat, 02 Aug 2025 12:27:37 -0400
From: Steven Rostedt <rostedt@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Tomas Glozar <tglozar@...hat.com>,
John Kacur <jkacur@...hat.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [for-next][PATCH 3/6] tracing: Add guard() around locks and mutexes in trace.c
From: Steven Rostedt <rostedt@...dmis.org>
There's several locations in trace.c that can be simplified by using
guards around raw_spin_lock_irqsave, mutexes and preempt disabling.
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Link: https://lore.kernel.org/20250801203857.879085376@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
kernel/trace/trace.c | 144 ++++++++++++++-----------------------------
1 file changed, 46 insertions(+), 98 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 332487179e1d..4299e89ed04e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -432,15 +432,13 @@ static void ftrace_exports(struct ring_buffer_event *event, int flag)
{
struct trace_export *export;
- preempt_disable_notrace();
+ guard(preempt_notrace)();
export = rcu_dereference_raw_check(ftrace_exports_list);
while (export) {
trace_process_export(export, event, flag);
export = rcu_dereference_raw_check(export->next);
}
-
- preempt_enable_notrace();
}
static inline void
@@ -497,27 +495,18 @@ int register_ftrace_export(struct trace_export *export)
if (WARN_ON_ONCE(!export->write))
return -1;
- mutex_lock(&ftrace_export_lock);
+ guard(mutex)(&ftrace_export_lock);
add_ftrace_export(&ftrace_exports_list, export);
- mutex_unlock(&ftrace_export_lock);
-
return 0;
}
EXPORT_SYMBOL_GPL(register_ftrace_export);
int unregister_ftrace_export(struct trace_export *export)
{
- int ret;
-
- mutex_lock(&ftrace_export_lock);
-
- ret = rm_ftrace_export(&ftrace_exports_list, export);
-
- mutex_unlock(&ftrace_export_lock);
-
- return ret;
+ guard(mutex)(&ftrace_export_lock);
+ return rm_ftrace_export(&ftrace_exports_list, export);
}
EXPORT_SYMBOL_GPL(unregister_ftrace_export);
@@ -640,9 +629,8 @@ void trace_array_put(struct trace_array *this_tr)
if (!this_tr)
return;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
__trace_array_put(this_tr);
- mutex_unlock(&trace_types_lock);
}
EXPORT_SYMBOL_GPL(trace_array_put);
@@ -1424,13 +1412,8 @@ static int tracing_arm_snapshot_locked(struct trace_array *tr)
int tracing_arm_snapshot(struct trace_array *tr)
{
- int ret;
-
- mutex_lock(&trace_types_lock);
- ret = tracing_arm_snapshot_locked(tr);
- mutex_unlock(&trace_types_lock);
-
- return ret;
+ guard(mutex)(&trace_types_lock);
+ return tracing_arm_snapshot_locked(tr);
}
void tracing_disarm_snapshot(struct trace_array *tr)
@@ -2483,9 +2466,8 @@ void tracing_reset_all_online_cpus_unlocked(void)
void tracing_reset_all_online_cpus(void)
{
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
tracing_reset_all_online_cpus_unlocked();
- mutex_unlock(&trace_types_lock);
}
int is_tracing_stopped(void)
@@ -2496,18 +2478,17 @@ int is_tracing_stopped(void)
static void tracing_start_tr(struct trace_array *tr)
{
struct trace_buffer *buffer;
- unsigned long flags;
if (tracing_disabled)
return;
- raw_spin_lock_irqsave(&tr->start_lock, flags);
+ guard(raw_spinlock_irqsave)(&tr->start_lock);
if (--tr->stop_count) {
if (WARN_ON_ONCE(tr->stop_count < 0)) {
/* Someone screwed up their debugging */
tr->stop_count = 0;
}
- goto out;
+ return;
}
/* Prevent the buffers from switching */
@@ -2524,9 +2505,6 @@ static void tracing_start_tr(struct trace_array *tr)
#endif
arch_spin_unlock(&tr->max_lock);
-
- out:
- raw_spin_unlock_irqrestore(&tr->start_lock, flags);
}
/**
@@ -2544,11 +2522,10 @@ void tracing_start(void)
static void tracing_stop_tr(struct trace_array *tr)
{
struct trace_buffer *buffer;
- unsigned long flags;
- raw_spin_lock_irqsave(&tr->start_lock, flags);
+ guard(raw_spinlock_irqsave)(&tr->start_lock);
if (tr->stop_count++)
- goto out;
+ return;
/* Prevent the buffers from switching */
arch_spin_lock(&tr->max_lock);
@@ -2564,9 +2541,6 @@ static void tracing_stop_tr(struct trace_array *tr)
#endif
arch_spin_unlock(&tr->max_lock);
-
- out:
- raw_spin_unlock_irqrestore(&tr->start_lock, flags);
}
/**
@@ -2679,12 +2653,12 @@ void trace_buffered_event_enable(void)
per_cpu(trace_buffered_event, cpu) = event;
- preempt_disable();
- if (cpu == smp_processor_id() &&
- __this_cpu_read(trace_buffered_event) !=
- per_cpu(trace_buffered_event, cpu))
- WARN_ON_ONCE(1);
- preempt_enable();
+ scoped_guard(preempt,) {
+ if (cpu == smp_processor_id() &&
+ __this_cpu_read(trace_buffered_event) !=
+ per_cpu(trace_buffered_event, cpu))
+ WARN_ON_ONCE(1);
+ }
}
}
@@ -3029,7 +3003,7 @@ static void __ftrace_trace_stack(struct trace_array *tr,
skip++;
#endif
- preempt_disable_notrace();
+ guard(preempt_notrace)();
stackidx = __this_cpu_inc_return(ftrace_stack_reserve) - 1;
@@ -3087,8 +3061,6 @@ static void __ftrace_trace_stack(struct trace_array *tr,
/* Again, don't let gcc optimize things here */
barrier();
__this_cpu_dec(ftrace_stack_reserve);
- preempt_enable_notrace();
-
}
static inline void ftrace_trace_stack(struct trace_array *tr,
@@ -3171,9 +3143,9 @@ ftrace_trace_userstack(struct trace_array *tr,
* prevent recursion, since the user stack tracing may
* trigger other kernel events.
*/
- preempt_disable();
+ guard(preempt)();
if (__this_cpu_read(user_stack_count))
- goto out;
+ return;
__this_cpu_inc(user_stack_count);
@@ -3191,8 +3163,6 @@ ftrace_trace_userstack(struct trace_array *tr,
out_drop_count:
__this_cpu_dec(user_stack_count);
- out:
- preempt_enable();
}
#else /* CONFIG_USER_STACKTRACE_SUPPORT */
static void ftrace_trace_userstack(struct trace_array *tr,
@@ -3374,7 +3344,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
pause_graph_tracing();
trace_ctx = tracing_gen_ctx();
- preempt_disable_notrace();
+ guard(preempt_notrace)();
tbuffer = get_trace_buf();
if (!tbuffer) {
@@ -3406,7 +3376,6 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
put_trace_buf();
out_nobuffer:
- preempt_enable_notrace();
unpause_graph_tracing();
return len;
@@ -3430,7 +3399,7 @@ int __trace_array_vprintk(struct trace_buffer *buffer,
pause_graph_tracing();
trace_ctx = tracing_gen_ctx();
- preempt_disable_notrace();
+ guard(preempt_notrace)();
tbuffer = get_trace_buf();
@@ -3458,7 +3427,6 @@ int __trace_array_vprintk(struct trace_buffer *buffer,
put_trace_buf();
out_nobuffer:
- preempt_enable_notrace();
unpause_graph_tracing();
return len;
@@ -4788,20 +4756,16 @@ int tracing_open_file_tr(struct inode *inode, struct file *filp)
if (ret)
return ret;
- mutex_lock(&event_mutex);
+ guard(mutex)(&event_mutex);
/* Fail if the file is marked for removal */
if (file->flags & EVENT_FILE_FL_FREED) {
trace_array_put(file->tr);
- ret = -ENODEV;
+ return -ENODEV;
} else {
event_file_get(file);
}
- mutex_unlock(&event_mutex);
- if (ret)
- return ret;
-
filp->private_data = inode->i_private;
return 0;
@@ -5945,9 +5909,9 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf,
char buf[MAX_TRACER_SIZE+2];
int r;
- mutex_lock(&trace_types_lock);
- r = sprintf(buf, "%s\n", tr->current_trace->name);
- mutex_unlock(&trace_types_lock);
+ scoped_guard(mutex, &trace_types_lock) {
+ r = sprintf(buf, "%s\n", tr->current_trace->name);
+ }
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
@@ -6249,15 +6213,13 @@ int tracing_update_buffers(struct trace_array *tr)
{
int ret = 0;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
update_last_data(tr);
if (!tr->ring_buffer_expanded)
ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
RING_BUFFER_ALL_CPUS);
- mutex_unlock(&trace_types_lock);
-
return ret;
}
@@ -6554,7 +6516,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
if (ret)
return ret;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
cpu = tracing_get_cpu(inode);
ret = open_pipe_on_cpu(tr, cpu);
if (ret)
@@ -6598,7 +6560,6 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
tr->trace_ref++;
- mutex_unlock(&trace_types_lock);
return ret;
fail:
@@ -6607,7 +6568,6 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
close_pipe_on_cpu(tr, cpu);
fail_pipe_on_cpu:
__trace_array_put(tr);
- mutex_unlock(&trace_types_lock);
return ret;
}
@@ -6616,14 +6576,13 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
struct trace_iterator *iter = file->private_data;
struct trace_array *tr = inode->i_private;
- mutex_lock(&trace_types_lock);
+ scoped_guard(mutex, &trace_types_lock) {
+ tr->trace_ref--;
- tr->trace_ref--;
-
- if (iter->trace->pipe_close)
- iter->trace->pipe_close(iter);
- close_pipe_on_cpu(tr, iter->cpu_file);
- mutex_unlock(&trace_types_lock);
+ if (iter->trace->pipe_close)
+ iter->trace->pipe_close(iter);
+ close_pipe_on_cpu(tr, iter->cpu_file);
+ }
free_trace_iter_content(iter);
kfree(iter);
@@ -7426,7 +7385,7 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
if (i == ARRAY_SIZE(trace_clocks))
return -EINVAL;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
tr->clock_id = i;
@@ -7450,8 +7409,6 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
tscratch->clock_id = i;
}
- mutex_unlock(&trace_types_lock);
-
return 0;
}
@@ -7503,15 +7460,13 @@ static int tracing_time_stamp_mode_show(struct seq_file *m, void *v)
{
struct trace_array *tr = m->private;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
if (ring_buffer_time_stamp_abs(tr->array_buffer.buffer))
seq_puts(m, "delta [absolute]\n");
else
seq_puts(m, "[delta] absolute\n");
- mutex_unlock(&trace_types_lock);
-
return 0;
}
@@ -8099,14 +8054,14 @@ static void clear_tracing_err_log(struct trace_array *tr)
{
struct tracing_log_err *err, *next;
- mutex_lock(&tracing_err_log_lock);
+ guard(mutex)(&tracing_err_log_lock);
+
list_for_each_entry_safe(err, next, &tr->err_log, list) {
list_del(&err->list);
free_tracing_log_err(err);
}
tr->n_err_log_entries = 0;
- mutex_unlock(&tracing_err_log_lock);
}
static void *tracing_err_log_seq_start(struct seq_file *m, loff_t *pos)
@@ -8377,7 +8332,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
struct ftrace_buffer_info *info = file->private_data;
struct trace_iterator *iter = &info->iter;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
iter->tr->trace_ref--;
@@ -8388,8 +8343,6 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
info->spare_cpu, info->spare);
kvfree(info);
- mutex_unlock(&trace_types_lock);
-
return 0;
}
@@ -8597,14 +8550,13 @@ static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned
* An ioctl call with cmd 0 to the ring buffer file will wake up all
* waiters
*/
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
/* Make sure the waiters see the new wait_index */
(void)atomic_fetch_inc_release(&iter->wait_index);
ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file);
- mutex_unlock(&trace_types_lock);
return 0;
}
@@ -9094,10 +9046,9 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
return -EINVAL;
if (!!(topt->flags->val & topt->opt->bit) != val) {
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
ret = __set_tracer_option(topt->tr, topt->flags,
topt->opt, !val);
- mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}
@@ -9406,7 +9357,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
return ret;
if (buffer) {
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
if (!!val == tracer_tracing_is_on(tr)) {
val = 0; /* do nothing */
} else if (val) {
@@ -9420,7 +9371,6 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
/* Wake up any waiters */
ring_buffer_wake_waiters(buffer, RING_BUFFER_ALL_CPUS);
}
- mutex_unlock(&trace_types_lock);
}
(*ppos)++;
@@ -9804,10 +9754,9 @@ static void __update_tracer_options(struct trace_array *tr)
static void update_tracer_options(struct trace_array *tr)
{
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
tracer_options_updated = true;
__update_tracer_options(tr);
- mutex_unlock(&trace_types_lock);
}
/* Must have trace_types_lock held */
@@ -9829,11 +9778,10 @@ struct trace_array *trace_array_find_get(const char *instance)
{
struct trace_array *tr;
- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);
tr = trace_array_find(instance);
if (tr)
tr->ref++;
- mutex_unlock(&trace_types_lock);
return tr;
}
--
2.47.2
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