From: "Masami Hiramatsu (Google)" mhiramat@kernel.org

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.

Link: https://lore.kernel.org/linux-trace-kernel/167033628155.4111793.121854056908...

Fixes: 424b650f35c7 ("tracing: Fix missing osnoise tracer on max_latency") Cc: Daniel Bristot de Oliveira bristot@kernel.org Cc: stable@vger.kernel.org Reported-by: David Howells dhowells@redhat.com Reported-by: kernel test robot lkp@intel.com Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Link: https://lore.kernel.org/all/166992525941.1716618.13740663757583361463.stgit@... (original thread and v1) Link: https://lore.kernel.org/all/202212052253.VuhZ2ulJ-lkp@intel.com/T/#u (v1 error report) Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- 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 948f321b9df1..664619b3f1e1 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) @@ -6577,7 +6578,7 @@ 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, @@ -7592,7 +7593,7 @@ 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, @@ -9606,7 +9607,9 @@ 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 8f37ff032b4f..9dc920b01c17 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);