Messages in this thread Patch in this message | | | Date | Mon, 5 Dec 2022 18:06:17 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [PATCH] trace: Fix some checker warnings |
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On Mon, 05 Dec 2022 08:28:35 +0000 David Howells <dhowells@redhat.com> wrote:
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > > > +#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) > > > static const struct file_operations tracing_max_lat_fops; > > > +#endif > > > > Oops, I missed this part. Why did you introduced this #ifdefs? > > Because: > > #if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) > static const struct file_operations tracing_max_lat_fops = { > > in the same file. You get something like an unused symbol warning otherwise > if neither config option is defined.
Yeah, I got it. Without the above change, the compile error will be gone, but this means that the declaration becomes a definition. (it uses an empty data structure)
Could you remove that part from your printf checker macro, and apply the below patch? Since the printf macros are a kind of improvement but this part is an actual bug, need to be fixed on stable kernel too.
From 2e993ec80d864677fd42d27f9d4ee01d7e63f8a4 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> Date: Mon, 5 Dec 2022 14:27:00 +0900 Subject: [PATCH] tracing: Fix complicated dependency of CONFIG_TRACER_MAX_TRACE
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@vger.kernel.org Reported-by: David Howells <dhowells@redhat.com> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- kernel/trace/Kconfig | 2 ++ kernel/trace/trace.c | 15 ++++++++------- kernel/trace/trace.h | 8 +++----- 3 files changed, 13 insertions(+), 12 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..08033347df2c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1692,6 +1692,8 @@ 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 +1750,14 @@ 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, @@ -1888,6 +1886,7 @@ 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 +6571,7 @@ 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 +7586,7 @@ 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 +9600,9 @@ 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); -- 2.39.0.rc0.267.gcb52ba06e7-goog -- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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