[PATCH v2] tracing: Fix complicated dependency of CONFIG_TRACER_MAX_TRACE
From: Masami Hiramatsu (Google)
Date: Tue Dec 06 2022 - 09:18:13 EST
From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Both CONFIG_OSNOISE_TRACER and CONFIG_HWLAT_TRACER partially enables the
CONFIG_TRACER_MAX_TRACE code, but that is complicated and has
introduced a bug; It declares tracing_max_lat_fops data structure outside
of #ifdefs, but since it is defined only when CONFIG_TRACER_MAX_TRACE=y
or CONFIG_HWLAT_TRACER=y, if only CONFIG_OSNOISE_TRACER=y, that
declaration comes to a definition(!).
To fix this issue, and do not repeat the similar problem, makes
CONFIG_OSNOISE_TRACER and CONFIG_HWLAT_TRACER enables the
CONFIG_TRACER_MAX_TRACE always. It has there benefits;
- Fix the tracing_max_lat_fops bug
- Simplify the #ifdefs
- CONFIG_TRACER_MAX_TRACE code is fully enabled, or not.
Fixes: 424b650f35c7 ("tracing: Fix missing osnoise tracer on max_latency")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: David Howells <dhowells@xxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/all/166992525941.1716618.13740663757583361463.stgit@xxxxxxxxxxxxxxxxxxxxxx/ (original thread and v1)
Link: https://lore.kernel.org/all/202212052253.VuhZ2ulJ-lkp@xxxxxxxxx/T/#u (v1 error report)
---
Changes in v2:
- Fix errors with the combination of CONFIG_TRACER_MAX_TRACE=y and
CONFIG_TRACER_SNAPSHOT=n.
---
kernel/trace/Kconfig | 2 ++
kernel/trace/trace.c | 23 +++++++++++++----------
kernel/trace/trace.h | 8 +++-----
3 files changed, 18 insertions(+), 15 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e9e95c790b8e..93d724996283 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -375,6 +375,7 @@ config SCHED_TRACER
config HWLAT_TRACER
bool "Tracer to detect hardware latencies (like SMIs)"
select GENERIC_TRACER
+ select TRACER_MAX_TRACE
help
This tracer, when enabled will create one or more kernel threads,
depending on what the cpumask file is set to, which each thread
@@ -410,6 +411,7 @@ config HWLAT_TRACER
config OSNOISE_TRACER
bool "OS Noise tracer"
select GENERIC_TRACER
+ select TRACER_MAX_TRACE
help
In the context of high-performance computing (HPC), the Operating
System Noise (osnoise) refers to the interference experienced by an
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5cfc95a52bc3..459ff8cf768a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1421,6 +1421,7 @@ int tracing_snapshot_cond_disable(struct trace_array *tr)
return false;
}
EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable);
+#define free_snapshot(tr) do { } while (0)
#endif /* CONFIG_TRACER_SNAPSHOT */
void tracer_tracing_off(struct trace_array *tr)
@@ -1692,6 +1693,8 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
}
unsigned long __read_mostly tracing_thresh;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
static const struct file_operations tracing_max_lat_fops;
#ifdef LATENCY_FS_NOTIFY
@@ -1748,18 +1751,14 @@ void latency_fsnotify(struct trace_array *tr)
irq_work_queue(&tr->fsnotify_irqwork);
}
-#elif defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
- || defined(CONFIG_OSNOISE_TRACER)
+#else /* !LATENCY_FS_NOTIFY */
#define trace_create_maxlat_file(tr, d_tracer) \
trace_create_file("tracing_max_latency", TRACE_MODE_WRITE, \
d_tracer, &tr->max_latency, &tracing_max_lat_fops)
-#else
-#define trace_create_maxlat_file(tr, d_tracer) do { } while (0)
#endif
-#ifdef CONFIG_TRACER_MAX_TRACE
/*
* Copy the new maximum trace into the separate maximum-trace
* structure. (this way the maximum trace is permanently saved,
@@ -1834,14 +1833,15 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
ring_buffer_record_off(tr->max_buffer.buffer);
#ifdef CONFIG_TRACER_SNAPSHOT
- if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data))
- goto out_unlock;
+ if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data)) {
+ arch_spin_unlock(&tr->max_lock);
+ return;
+ }
#endif
swap(tr->array_buffer.buffer, tr->max_buffer.buffer);
__update_max_tr(tr, tsk, cpu);
- out_unlock:
arch_spin_unlock(&tr->max_lock);
}
@@ -1888,6 +1888,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
__update_max_tr(tr, tsk, cpu);
arch_spin_unlock(&tr->max_lock);
}
+
#endif /* CONFIG_TRACER_MAX_TRACE */
static int wait_on_pipe(struct trace_iterator *iter, int full)
@@ -6572,7 +6573,7 @@ tracing_thresh_write(struct file *filp, const char __user *ubuf,
return ret;
}
-#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
+#ifdef CONFIG_TRACER_MAX_TRACE
static ssize_t
tracing_max_lat_read(struct file *filp, char __user *ubuf,
@@ -7587,7 +7588,7 @@ static const struct file_operations tracing_thresh_fops = {
.llseek = generic_file_llseek,
};
-#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
+#ifdef CONFIG_TRACER_MAX_TRACE
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
@@ -9601,7 +9602,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
create_trace_options_dir(tr);
+#ifdef CONFIG_TRACER_MAX_TRACE
trace_create_maxlat_file(tr, d_tracer);
+#endif
if (ftrace_create_function_files(tr, d_tracer))
MEM_FAIL(1, "Could not allocate function filter files");
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d42e24507152..8b69698780a1 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -308,8 +308,7 @@ struct trace_array {
struct array_buffer max_buffer;
bool allocated_snapshot;
#endif
-#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
- || defined(CONFIG_OSNOISE_TRACER)
+#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long max_latency;
#ifdef CONFIG_FSNOTIFY
struct dentry *d_max_latency;
@@ -688,12 +687,11 @@ void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
void *cond_data);
void update_max_tr_single(struct trace_array *tr,
struct task_struct *tsk, int cpu);
-#endif /* CONFIG_TRACER_MAX_TRACE */
-#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
- || defined(CONFIG_OSNOISE_TRACER)) && defined(CONFIG_FSNOTIFY)
+#ifdef CONFIG_FSNOTIFY
#define LATENCY_FS_NOTIFY
#endif
+#endif /* CONFIG_TRACER_MAX_TRACE */
#ifdef LATENCY_FS_NOTIFY
void latency_fsnotify(struct trace_array *tr);