[PATCH v5 20/22] tracing/boot: Add cpu_mask option support

From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>,
	Frank Rowand <frowand.list@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Namhyung Kim <namhyung@kernel.org>, Tim Bird <Tim.Bird@sony.com>,
	Jiri Olsa <jolsa@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	Rob Herring <robh+dt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 20/22] tracing/boot: Add cpu_mask option support
Date: Thu, 26 Dec 2019 23:07:51 +0900	[thread overview]
Message-ID: <157736927104.11126.4469386216175738596.stgit@devnote2> (raw)
In-Reply-To: <157736902773.11126.2531161235817081873.stgit@devnote2>

Add ftrace.cpumask option support to boot-time tracing.
This sets cpumask for each instance.

 - ftrace.[instance.INSTANCE.]cpumask = CPUMASK;
   Set the trace cpumask. Note that the CPUMASK should be a string
   which <tracefs>/tracing_cpumask can accepts.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 0 files changed

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c2e1b33aec17..5791e6b5136f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4561,20 +4561,13 @@ tracing_cpumask_read(struct file *filp, char __user *ubuf,
 	return count;
 }
 
-static ssize_t
-tracing_cpumask_write(struct file *filp, const char __user *ubuf,
-		      size_t count, loff_t *ppos)
+int tracing_set_cpumask(struct trace_array *tr,
+			cpumask_var_t tracing_cpumask_new)
 {
-	struct trace_array *tr = file_inode(filp)->i_private;
-	cpumask_var_t tracing_cpumask_new;
-	int err, cpu;
-
-	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
-		return -ENOMEM;
+	int cpu;
 
-	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
-	if (err)
-		goto err_unlock;
+	if (!tr)
+		return -EINVAL;
 
 	local_irq_disable();
 	arch_spin_lock(&tr->max_lock);
@@ -4598,11 +4591,34 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 	local_irq_enable();
 
 	cpumask_copy(tr->tracing_cpumask, tracing_cpumask_new);
+
+	return 0;
+}
+
+static ssize_t
+tracing_cpumask_write(struct file *filp, const char __user *ubuf,
+		      size_t count, loff_t *ppos)
+{
+	struct trace_array *tr = file_inode(filp)->i_private;
+	cpumask_var_t tracing_cpumask_new;
+	int err;
+
+	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
+		return -ENOMEM;
+
+	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
+	if (err)
+		goto err_free;
+
+	err = tracing_set_cpumask(tr, tracing_cpumask_new);
+	if (err)
+		goto err_free;
+
 	free_cpumask_var(tracing_cpumask_new);
 
 	return count;
 
-err_unlock:
+err_free:
 	free_cpumask_var(tracing_cpumask_new);
 
 	return err;
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index f5db30d25b0b..81d923c16a4d 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -18,6 +18,8 @@ extern int trace_set_options(struct trace_array *tr, char *option);
 extern int tracing_set_tracer(struct trace_array *tr, const char *buf);
 extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
 					  unsigned long size, int cpu_id);
+extern int tracing_set_cpumask(struct trace_array *tr,
+				cpumask_var_t tracing_cpumask_new);
 
 static void __init
 trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
@@ -52,6 +54,18 @@ trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
 		if (tracing_resize_ring_buffer(tr, v, RING_BUFFER_ALL_CPUS) < 0)
 			pr_err("Failed to resize trace buffer to %s\n", p);
 	}
+
+	p = xbc_node_find_value(node, "cpumask", NULL);
+	if (p && *p != '\0') {
+		cpumask_var_t new_mask;
+
+		if (alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
+			if (cpumask_parse(p, new_mask) < 0 ||
+			    tracing_set_cpumask(tr, new_mask) < 0)
+				pr_err("Failed to set new CPU mask %s\n", p);
+			free_cpumask_var(new_mask);
+		}
+	}
 }
 
 #ifdef CONFIG_EVENT_TRACING

