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Subject[RFC PATCH v4 20/22] tracing/boot: Add cpu_mask option support
Date
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>
---
kernel/trace/trace.c | 42 +++++++++++++++++++++++++++++-------------
kernel/trace/trace_boot.c | 14 ++++++++++++++
2 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c19dce22f5bd..008d3788331a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4555,20 +4555,13 @@ 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);
@@ -4592,11 +4585,34 @@ 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
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