* [PATCH 1/2] tracing: Better separate SNAPSHOT and MAX_TRACE options
2026-02-06 16:35 [PATCH 0/2] tracing: Clean up snapshot config logic and field name Steven Rostedt
@ 2026-02-06 16:35 ` Steven Rostedt
2026-02-06 16:35 ` [PATCH 2/2] tracing: Rename trace_array field max_buffer to snapshot_buffer Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Steven Rostedt @ 2026-02-06 16:35 UTC (permalink / raw)
To: linux-kernel, linux-trace-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton
From: Steven Rostedt <rostedt@goodmis.org>
The latency tracers (scheduler, irqsoff, etc) were created when tracing
was first added. These tracers required a "snapshot" buffer that was the
same size as the ring buffer being written to. When a new max latency was
hit, the main ring buffer would swap with the snapshot buffer so that the
trace leading up to the latency would be saved in the snapshot buffer (The
snapshot buffer is never written to directly and the data within it can be
viewed without fear of being overwritten).
Later, a new feature was added to allow snapshots to be taken by user
space or even event triggers. This created a "snapshot" file that allowed
users to trigger a snapshot from user space to save the current trace.
The config for this new feature (CONFIG_TRACER_SNAPSHOT) would select the
latency tracer config (CONFIG_TRACER_MAX_LATENCY) as it would need all the
functionality from it as it already existed. But this was incorrect. As
the snapshot feature is really what the latency tracers need and not the
other way around.
Have CONFIG_TRACER_MAX_TRACE select CONFIG_TRACER_SNAPSHOT where the
tracers that needs the max latency buffer selects the TRACE_MAX_TRACE
which will then select TRACER_SNAPSHOT.
Also, go through trace.c and trace.h and make the code that only needs the
TRACER_MAX_TRACE protected by that and the code that always requires the
snapshot to be protected by TRACER_SNAPSHOT.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/Kconfig | 8 +++----
kernel/trace/trace.c | 50 ++++++++++++++++++++++----------------------
kernel/trace/trace.h | 11 ++++++----
3 files changed, 36 insertions(+), 33 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index bfa2ec46e075..bedb2f982823 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -133,6 +133,7 @@ config BUILDTIME_MCOUNT_SORT
config TRACER_MAX_TRACE
bool
+ select TRACER_SNAPSHOT
config TRACE_CLOCK
bool
@@ -422,7 +423,6 @@ config IRQSOFF_TRACER
select GENERIC_TRACER
select TRACER_MAX_TRACE
select RING_BUFFER_ALLOW_SWAP
- select TRACER_SNAPSHOT
select TRACER_SNAPSHOT_PER_CPU_SWAP
help
This option measures the time spent in irqs-off critical
@@ -445,7 +445,6 @@ config PREEMPT_TRACER
select GENERIC_TRACER
select TRACER_MAX_TRACE
select RING_BUFFER_ALLOW_SWAP
- select TRACER_SNAPSHOT
select TRACER_SNAPSHOT_PER_CPU_SWAP
select TRACE_PREEMPT_TOGGLE
help
@@ -467,7 +466,6 @@ config SCHED_TRACER
select GENERIC_TRACER
select CONTEXT_SWITCH_TRACER
select TRACER_MAX_TRACE
- select TRACER_SNAPSHOT
help
This tracer tracks the latency of the highest priority task
to be scheduled in, starting from the point it has woken up.
@@ -617,7 +615,6 @@ config TRACE_SYSCALL_BUF_SIZE_DEFAULT
config TRACER_SNAPSHOT
bool "Create a snapshot trace buffer"
- select TRACER_MAX_TRACE
help
Allow tracing users to take snapshot of the current buffer using the
ftrace interface, e.g.:
@@ -625,6 +622,9 @@ config TRACER_SNAPSHOT
echo 1 > /sys/kernel/tracing/snapshot
cat snapshot
+ Note, the latency tracers select this option. To disable it,
+ all the latency tracers need to be disabled.
+
config TRACER_SNAPSHOT_PER_CPU_SWAP
bool "Allow snapshot to swap per CPU"
depends on TRACER_SNAPSHOT
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index abf28f92b678..54851ffbabeb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1720,7 +1720,7 @@ static int wait_on_pipe(struct trace_iterator *iter, int full)
ret = ring_buffer_wait(iter->array_buffer->buffer, iter->cpu_file, full,
wait_pipe_cond, &pwait);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
/*
* Make sure this is still the snapshot buffer, as if a snapshot were
* to happen, this would now be the main buffer.
@@ -2063,7 +2063,7 @@ void tracing_reset_all_online_cpus_unlocked(void)
continue;
tr->clear_trace = false;
tracing_reset_online_cpus(&tr->array_buffer);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
tracing_reset_online_cpus(&tr->max_buffer);
#endif
}
@@ -2103,7 +2103,7 @@ static void tracing_start_tr(struct trace_array *tr)
if (buffer)
ring_buffer_record_enable(buffer);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
buffer = tr->max_buffer.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
@@ -2139,7 +2139,7 @@ static void tracing_stop_tr(struct trace_array *tr)
if (buffer)
ring_buffer_record_disable(buffer);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
buffer = tr->max_buffer.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
@@ -3766,7 +3766,7 @@ static void test_ftrace_alive(struct seq_file *m)
"# MAY BE MISSING FUNCTION EVENTS\n");
}
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
static void show_snapshot_main_help(struct seq_file *m)
{
seq_puts(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n"
@@ -3944,7 +3944,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
iter->tr = tr;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
/* Currently only the top directory has a snapshot */
if (tr->current_trace->print_max || snapshot)
iter->array_buffer = &tr->max_buffer;
@@ -4181,7 +4181,7 @@ static int tracing_open(struct inode *inode, struct file *file)
static bool
trace_ok_for_array(struct tracer *t, struct trace_array *tr)
{
-#ifdef CONFIG_TRACER_SNAPSHOT
+#ifdef CONFIG_TRACER_MAX_TRACE
/* arrays with mapped buffer range do not have snapshots */
if (tr->range_addr_start && t->use_max_tr)
return false;
@@ -4362,14 +4362,14 @@ int tracing_set_cpumask(struct trace_array *tr,
if (cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
ring_buffer_record_disable_cpu(tr->array_buffer.buffer, cpu);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
ring_buffer_record_disable_cpu(tr->max_buffer.buffer, cpu);
#endif
}
if (!cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
ring_buffer_record_enable_cpu(tr->array_buffer.buffer, cpu);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
ring_buffer_record_enable_cpu(tr->max_buffer.buffer, cpu);
#endif
}
@@ -4579,7 +4579,7 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
case TRACE_ITER(OVERWRITE):
ring_buffer_change_overwrite(tr->array_buffer.buffer, enabled);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
#endif
break;
@@ -5243,7 +5243,7 @@ static void update_buffer_entries(struct array_buffer *buf, int cpu)
}
}
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
/* resize @tr's buffer to the size of @size_tr's entries */
static int resize_buffer_duplicate_size(struct array_buffer *trace_buf,
struct array_buffer *size_buf, int cpu_id)
@@ -5269,7 +5269,7 @@ static int resize_buffer_duplicate_size(struct array_buffer *trace_buf,
return ret;
}
-#endif /* CONFIG_TRACER_MAX_TRACE */
+#endif /* CONFIG_TRACER_SNAPSHOT */
static int __tracing_resize_ring_buffer(struct trace_array *tr,
unsigned long size, int cpu)
@@ -5294,7 +5294,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
if (ret < 0)
goto out_start;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
if (!tr->allocated_snapshot)
goto out;
@@ -5326,7 +5326,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
update_buffer_entries(&tr->max_buffer, cpu);
out:
-#endif /* CONFIG_TRACER_MAX_TRACE */
+#endif /* CONFIG_TRACER_SNAPSHOT */
update_buffer_entries(&tr->array_buffer, cpu);
out_start:
@@ -5583,7 +5583,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
if (trace == tr->current_trace)
return 0;
-#ifdef CONFIG_TRACER_SNAPSHOT
+#ifdef CONFIG_TRACER_MAX_TRACE
if (trace->use_max_tr) {
local_irq_disable();
arch_spin_lock(&tr->max_lock);
@@ -7039,7 +7039,7 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
*/
tracing_reset_online_cpus(&tr->array_buffer);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
if (tr->max_buffer.buffer)
ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);
tracing_reset_online_cpus(&tr->max_buffer);
@@ -8190,7 +8190,7 @@ static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned
return 0;
}
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
static int get_snapshot_map(struct trace_array *tr)
{
int err = 0;
@@ -9194,7 +9194,7 @@ buffer_subbuf_size_write(struct file *filp, const char __user *ubuf,
if (ret)
goto out;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
if (!tr->allocated_snapshot)
goto out_max;
@@ -9415,7 +9415,7 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
if (ret)
return ret;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
/* Fix mapped buffer trace arrays do not have snapshot buffers */
if (tr->range_addr_start)
return 0;
@@ -9442,7 +9442,7 @@ static void free_trace_buffers(struct trace_array *tr)
free_trace_buffer(&tr->array_buffer);
kfree(tr->module_delta);
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
free_trace_buffer(&tr->max_buffer);
#endif
}
@@ -9584,7 +9584,7 @@ trace_array_create_systems(const char *name, const char *systems,
tr->syscall_buf_sz = global_trace.syscall_buf_sz;
tr->max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
spin_lock_init(&tr->snapshot_trigger_lock);
#endif
tr->current_trace = &nop_trace;
@@ -10540,7 +10540,7 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
return done;
}
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
__init static bool tr_needs_alloc_snapshot(const char *name)
{
char *test;
@@ -10730,7 +10730,7 @@ __init static void enable_instances(void)
}
} else {
/* Only non mapped buffers have snapshot buffers */
- if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
+ if (IS_ENABLED(CONFIG_TRACER_SNAPSHOT))
do_allocate_snapshot(name);
}
@@ -10857,7 +10857,7 @@ __init static int tracer_alloc_buffers(void)
global_trace.current_trace_flags = nop_trace.flags;
global_trace.max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
spin_lock_init(&global_trace.snapshot_trigger_lock);
#endif
ftrace_init_global_array_ops(&global_trace);
@@ -10925,7 +10925,7 @@ struct trace_array *trace_get_global_array(void)
void __init ftrace_boot_snapshot(void)
{
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
struct trace_array *tr;
if (!snapshot_at_boot)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6bd5f4a87909..e6f4e10060be 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -329,7 +329,7 @@ struct trace_array {
struct list_head list;
char *name;
struct array_buffer array_buffer;
-#ifdef CONFIG_TRACER_MAX_TRACE
+#ifdef CONFIG_TRACER_SNAPSHOT
/*
* The max_buffer is used to snapshot the trace when a maximum
* latency is reached, or when the user initiates a snapshot.
@@ -345,13 +345,16 @@ struct trace_array {
bool allocated_snapshot;
spinlock_t snapshot_trigger_lock;
unsigned int snapshot;
+#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long max_latency;
#ifdef CONFIG_FSNOTIFY
struct dentry *d_max_latency;
struct work_struct fsnotify_work;
struct irq_work fsnotify_irqwork;
-#endif
-#endif
+#endif /* CONFIG_FSNOTIFY */
+#endif /* CONFIG_TRACER_MAX_TRACE */
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
/* The below is for memory mapped ring buffer */
unsigned int mapped;
unsigned long range_addr_start;
@@ -377,7 +380,7 @@ struct trace_array {
*
* It is also used in other places outside the update_max_tr
* so it needs to be defined outside of the
- * CONFIG_TRACER_MAX_TRACE.
+ * CONFIG_TRACER_SNAPSHOT.
*/
arch_spinlock_t max_lock;
#ifdef CONFIG_FTRACE_SYSCALLS
--
2.51.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] tracing: Rename trace_array field max_buffer to snapshot_buffer
2026-02-06 16:35 [PATCH 0/2] tracing: Clean up snapshot config logic and field name Steven Rostedt
2026-02-06 16:35 ` [PATCH 1/2] tracing: Better separate SNAPSHOT and MAX_TRACE options Steven Rostedt
@ 2026-02-06 16:35 ` Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Steven Rostedt @ 2026-02-06 16:35 UTC (permalink / raw)
To: linux-kernel, linux-trace-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton
From: Steven Rostedt <rostedt@goodmis.org>
When tracing was first added, there were latency tracers that would take a
snapshot of the current trace when a new max latency was hit. This
snapshot buffer was called "max_buffer". Since then, a snapshot feature
was added that allowed user space or event triggers to trigger a snapshot
of the current buffer using the same max_buffer of the trace_array.
As this snapshot buffer now has a more generic use case, calling it
"max_buffer" is confusing. Rename it to snapshot_buffer.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 72 +++++++++++++++++------------------
kernel/trace/trace.h | 13 ++++---
kernel/trace/trace_selftest.c | 10 ++---
3 files changed, 48 insertions(+), 47 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 54851ffbabeb..dfa30711c6e2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -934,12 +934,12 @@ int tracing_alloc_snapshot_instance(struct trace_array *tr)
/* Make the snapshot buffer have the same order as main buffer */
order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
- ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order);
+ ret = ring_buffer_subbuf_order_set(tr->snapshot_buffer.buffer, order);
if (ret < 0)
return ret;
/* allocate spare buffer */
- ret = resize_buffer_duplicate_size(&tr->max_buffer,
+ ret = resize_buffer_duplicate_size(&tr->snapshot_buffer,
&tr->array_buffer, RING_BUFFER_ALL_CPUS);
if (ret < 0)
return ret;
@@ -957,10 +957,10 @@ static void free_snapshot(struct trace_array *tr)
* The max_tr ring buffer has some state (e.g. ring->clock) and
* we want preserve it.
*/
- ring_buffer_subbuf_order_set(tr->max_buffer.buffer, 0);
- ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
- set_buffer_entries(&tr->max_buffer, 1);
- tracing_reset_online_cpus(&tr->max_buffer);
+ ring_buffer_subbuf_order_set(tr->snapshot_buffer.buffer, 0);
+ ring_buffer_resize(tr->snapshot_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
+ set_buffer_entries(&tr->snapshot_buffer, 1);
+ tracing_reset_online_cpus(&tr->snapshot_buffer);
tr->allocated_snapshot = false;
}
@@ -1562,7 +1562,7 @@ static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct array_buffer *trace_buf = &tr->array_buffer;
- struct array_buffer *max_buf = &tr->max_buffer;
+ struct array_buffer *max_buf = &tr->snapshot_buffer;
struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu);
struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu);
@@ -1622,9 +1622,9 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
/* Inherit the recordable setting from array_buffer */
if (ring_buffer_record_is_set_on(tr->array_buffer.buffer))
- ring_buffer_record_on(tr->max_buffer.buffer);
+ ring_buffer_record_on(tr->snapshot_buffer.buffer);
else
- ring_buffer_record_off(tr->max_buffer.buffer);
+ ring_buffer_record_off(tr->snapshot_buffer.buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data)) {
@@ -1632,7 +1632,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
return;
}
#endif
- swap(tr->array_buffer.buffer, tr->max_buffer.buffer);
+ swap(tr->array_buffer.buffer, tr->snapshot_buffer.buffer);
__update_max_tr(tr, tsk, cpu);
@@ -1667,7 +1667,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
arch_spin_lock(&tr->max_lock);
- ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buffer, cpu);
+ ret = ring_buffer_swap_cpu(tr->snapshot_buffer.buffer, tr->array_buffer.buffer, cpu);
if (ret == -EBUSY) {
/*
@@ -1677,7 +1677,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
* and flag that it failed.
* Another reason is resize is in progress.
*/
- trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_,
+ trace_array_printk_buf(tr->snapshot_buffer.buffer, _THIS_IP_,
"Failed to swap buffers due to commit or resize in progress\n");
}
@@ -1726,7 +1726,7 @@ static int wait_on_pipe(struct trace_iterator *iter, int full)
* to happen, this would now be the main buffer.
*/
if (iter->snapshot)
- iter->array_buffer = &iter->tr->max_buffer;
+ iter->array_buffer = &iter->tr->snapshot_buffer;
#endif
return ret;
}
@@ -1794,7 +1794,7 @@ static int run_tracer_selftest(struct tracer *type)
if (type->use_max_tr) {
/* If we expanded the buffers, make sure the max is expanded too */
if (tr->ring_buffer_expanded)
- ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
+ ring_buffer_resize(tr->snapshot_buffer.buffer, trace_buf_size,
RING_BUFFER_ALL_CPUS);
tr->allocated_snapshot = true;
}
@@ -1821,7 +1821,7 @@ static int run_tracer_selftest(struct tracer *type)
/* Shrink the max buffer again */
if (tr->ring_buffer_expanded)
- ring_buffer_resize(tr->max_buffer.buffer, 1,
+ ring_buffer_resize(tr->snapshot_buffer.buffer, 1,
RING_BUFFER_ALL_CPUS);
}
#endif
@@ -2064,7 +2064,7 @@ void tracing_reset_all_online_cpus_unlocked(void)
tr->clear_trace = false;
tracing_reset_online_cpus(&tr->array_buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
- tracing_reset_online_cpus(&tr->max_buffer);
+ tracing_reset_online_cpus(&tr->snapshot_buffer);
#endif
}
}
@@ -2104,7 +2104,7 @@ static void tracing_start_tr(struct trace_array *tr)
ring_buffer_record_enable(buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
- buffer = tr->max_buffer.buffer;
+ buffer = tr->snapshot_buffer.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
#endif
@@ -2140,7 +2140,7 @@ static void tracing_stop_tr(struct trace_array *tr)
ring_buffer_record_disable(buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
- buffer = tr->max_buffer.buffer;
+ buffer = tr->snapshot_buffer.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
#endif
@@ -3947,7 +3947,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
#ifdef CONFIG_TRACER_SNAPSHOT
/* Currently only the top directory has a snapshot */
if (tr->current_trace->print_max || snapshot)
- iter->array_buffer = &tr->max_buffer;
+ iter->array_buffer = &tr->snapshot_buffer;
else
#endif
iter->array_buffer = &tr->array_buffer;
@@ -4150,7 +4150,7 @@ static int tracing_open(struct inode *inode, struct file *file)
#ifdef CONFIG_TRACER_MAX_TRACE
if (tr->current_trace->print_max)
- trace_buf = &tr->max_buffer;
+ trace_buf = &tr->snapshot_buffer;
#endif
if (cpu == RING_BUFFER_ALL_CPUS)
@@ -4363,14 +4363,14 @@ int tracing_set_cpumask(struct trace_array *tr,
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
ring_buffer_record_disable_cpu(tr->array_buffer.buffer, cpu);
#ifdef CONFIG_TRACER_SNAPSHOT
- ring_buffer_record_disable_cpu(tr->max_buffer.buffer, cpu);
+ ring_buffer_record_disable_cpu(tr->snapshot_buffer.buffer, cpu);
#endif
}
if (!cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
ring_buffer_record_enable_cpu(tr->array_buffer.buffer, cpu);
#ifdef CONFIG_TRACER_SNAPSHOT
- ring_buffer_record_enable_cpu(tr->max_buffer.buffer, cpu);
+ ring_buffer_record_enable_cpu(tr->snapshot_buffer.buffer, cpu);
#endif
}
}
@@ -4580,7 +4580,7 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
case TRACE_ITER(OVERWRITE):
ring_buffer_change_overwrite(tr->array_buffer.buffer, enabled);
#ifdef CONFIG_TRACER_SNAPSHOT
- ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
+ ring_buffer_change_overwrite(tr->snapshot_buffer.buffer, enabled);
#endif
break;
@@ -5298,7 +5298,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
if (!tr->allocated_snapshot)
goto out;
- ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);
+ ret = ring_buffer_resize(tr->snapshot_buffer.buffer, size, cpu);
if (ret < 0) {
int r = resize_buffer_duplicate_size(&tr->array_buffer,
&tr->array_buffer, cpu);
@@ -5323,7 +5323,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
goto out_start;
}
- update_buffer_entries(&tr->max_buffer, cpu);
+ update_buffer_entries(&tr->snapshot_buffer, cpu);
out:
#endif /* CONFIG_TRACER_SNAPSHOT */
@@ -7040,9 +7040,9 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
tracing_reset_online_cpus(&tr->array_buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
- if (tr->max_buffer.buffer)
- ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);
- tracing_reset_online_cpus(&tr->max_buffer);
+ if (tr->snapshot_buffer.buffer)
+ ring_buffer_set_clock(tr->snapshot_buffer.buffer, trace_clocks[i].func);
+ tracing_reset_online_cpus(&tr->snapshot_buffer);
#endif
if (tr->scratch && !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) {
@@ -7174,7 +7174,7 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
ret = 0;
iter->tr = tr;
- iter->array_buffer = &tr->max_buffer;
+ iter->array_buffer = &tr->snapshot_buffer;
iter->cpu_file = tracing_get_cpu(inode);
m->private = iter;
file->private_data = m;
@@ -7237,7 +7237,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
return -EINVAL;
#endif
if (tr->allocated_snapshot)
- ret = resize_buffer_duplicate_size(&tr->max_buffer,
+ ret = resize_buffer_duplicate_size(&tr->snapshot_buffer,
&tr->array_buffer, iter->cpu_file);
ret = tracing_arm_snapshot_locked(tr);
@@ -7258,9 +7258,9 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
default:
if (tr->allocated_snapshot) {
if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
- tracing_reset_online_cpus(&tr->max_buffer);
+ tracing_reset_online_cpus(&tr->snapshot_buffer);
else
- tracing_reset_cpu(&tr->max_buffer, iter->cpu_file);
+ tracing_reset_cpu(&tr->snapshot_buffer, iter->cpu_file);
}
break;
}
@@ -7316,7 +7316,7 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp)
}
info->iter.snapshot = true;
- info->iter.array_buffer = &info->iter.tr->max_buffer;
+ info->iter.array_buffer = &info->iter.tr->snapshot_buffer;
return ret;
}
@@ -9199,7 +9199,7 @@ buffer_subbuf_size_write(struct file *filp, const char __user *ubuf,
if (!tr->allocated_snapshot)
goto out_max;
- ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order);
+ ret = ring_buffer_subbuf_order_set(tr->snapshot_buffer.buffer, order);
if (ret) {
/* Put back the old order */
cnt = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, old_order);
@@ -9420,7 +9420,7 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
if (tr->range_addr_start)
return 0;
- ret = allocate_trace_buffer(tr, &tr->max_buffer,
+ ret = allocate_trace_buffer(tr, &tr->snapshot_buffer,
allocate_snapshot ? size : 1);
if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) {
free_trace_buffer(&tr->array_buffer);
@@ -9443,7 +9443,7 @@ static void free_trace_buffers(struct trace_array *tr)
kfree(tr->module_delta);
#ifdef CONFIG_TRACER_SNAPSHOT
- free_trace_buffer(&tr->max_buffer);
+ free_trace_buffer(&tr->snapshot_buffer);
#endif
}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e6f4e10060be..374b7c392f0a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -331,17 +331,18 @@ struct trace_array {
struct array_buffer array_buffer;
#ifdef CONFIG_TRACER_SNAPSHOT
/*
- * The max_buffer is used to snapshot the trace when a maximum
+ * The snapshot_buffer is used to snapshot the trace when a maximum
* latency is reached, or when the user initiates a snapshot.
* Some tracers will use this to store a maximum trace while
* it continues examining live traces.
*
- * The buffers for the max_buffer are set up the same as the array_buffer
- * When a snapshot is taken, the buffer of the max_buffer is swapped
- * with the buffer of the array_buffer and the buffers are reset for
- * the array_buffer so the tracing can continue.
+ * The buffers for the snapshot_buffer are set up the same as the
+ * array_buffer. When a snapshot is taken, the buffer of the
+ * snapshot_buffer is swapped with the buffer of the array_buffer
+ * and the buffers are reset for the array_buffer so the tracing can
+ * continue.
*/
- struct array_buffer max_buffer;
+ struct array_buffer snapshot_buffer;
bool allocated_snapshot;
spinlock_t snapshot_trigger_lock;
unsigned int snapshot;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index d88c44f1dfa5..be53fe6fee6a 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -1225,7 +1225,7 @@ trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
- ret = trace_test_buffer(&tr->max_buffer, &count);
+ ret = trace_test_buffer(&tr->snapshot_buffer, &count);
trace->reset(tr);
tracing_start();
@@ -1287,7 +1287,7 @@ trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
- ret = trace_test_buffer(&tr->max_buffer, &count);
+ ret = trace_test_buffer(&tr->snapshot_buffer, &count);
trace->reset(tr);
tracing_start();
@@ -1355,7 +1355,7 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
if (ret)
goto out;
- ret = trace_test_buffer(&tr->max_buffer, &count);
+ ret = trace_test_buffer(&tr->snapshot_buffer, &count);
if (ret)
goto out;
@@ -1385,7 +1385,7 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
if (ret)
goto out;
- ret = trace_test_buffer(&tr->max_buffer, &count);
+ ret = trace_test_buffer(&tr->snapshot_buffer, &count);
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
@@ -1513,7 +1513,7 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
/* check both trace buffers */
ret = trace_test_buffer(&tr->array_buffer, NULL);
if (!ret)
- ret = trace_test_buffer(&tr->max_buffer, &count);
+ ret = trace_test_buffer(&tr->snapshot_buffer, &count);
trace->reset(tr);
--
2.51.0
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