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Subject[PATCH v2 1/1] tracing: Make tracing_cpumask available for all instances
Date
Allow tracer instances to disable tracing by cpu by moving
the static global tracing_cpumask into trace_array.

Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Alexander Z Lam <azl@google.com>
---
kernel/trace/trace.c | 37 ++++++++++++++++++++-----------------
kernel/trace/trace.h | 1 +
2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 678a88b..e7ba6f0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3166,11 +3166,6 @@ static const struct file_operations show_traces_fops = {
};

/*
- * Only trace on a CPU if the bitmask is set:
- */
-static cpumask_var_t tracing_cpumask;
-
-/*
* The tracer itself will not take this lock, but still we want
* to provide a consistent cpumask to user-space:
*/
@@ -3186,11 +3181,12 @@ static ssize_t
tracing_cpumask_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
+ struct trace_array *tr = file_inode(filp)->i_private;
int len;

mutex_lock(&tracing_cpumask_update_lock);

- len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
+ len = cpumask_scnprintf(mask_str, count, tr->tracing_cpumask);
if (count - len < 2) {
count = -EINVAL;
goto out_err;
@@ -3208,7 +3204,7 @@ static ssize_t
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
- struct trace_array *tr = filp->private_data;
+ struct trace_array *tr = file_inode(filp)->i_private;
cpumask_var_t tracing_cpumask_new;
int err, cpu;

@@ -3228,12 +3224,12 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
* Increase/decrease the disabled counter if we are
* about to flip a bit in the cpumask:
*/
- if (cpumask_test_cpu(cpu, tracing_cpumask) &&
+ if (cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_inc(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
ring_buffer_record_disable_cpu(tr->trace_buffer.buffer, cpu);
}
- if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
+ if (!cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_dec(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
ring_buffer_record_enable_cpu(tr->trace_buffer.buffer, cpu);
@@ -3242,7 +3238,7 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
arch_spin_unlock(&ftrace_max_lock);
local_irq_enable();

- cpumask_copy(tracing_cpumask, tracing_cpumask_new);
+ cpumask_copy(tr->tracing_cpumask, tracing_cpumask_new);

mutex_unlock(&tracing_cpumask_update_lock);
free_cpumask_var(tracing_cpumask_new);
@@ -3256,9 +3252,10 @@ err_unlock:
}

static const struct file_operations tracing_cpumask_fops = {
- .open = tracing_open_generic,
+ .open = tracing_open_generic_tr,
.read = tracing_cpumask_read,
.write = tracing_cpumask_write,
+ .release = tracing_release_generic_tr,
.llseek = generic_file_llseek,
};

@@ -5937,6 +5934,11 @@ static int new_instance_create(const char *name)
if (!tr->name)
goto out_free_tr;

+ if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL))
+ goto out_free_tr;
+
+ cpumask_copy(tr->tracing_cpumask, cpu_all_mask);
+
raw_spin_lock_init(&tr->start_lock);

tr->current_trace = &nop_trace;
@@ -5968,6 +5970,7 @@ static int new_instance_create(const char *name)
out_free_tr:
if (tr->trace_buffer.buffer)
ring_buffer_free(tr->trace_buffer.buffer);
+ free_cpumask_var(tr->tracing_cpumask);
kfree(tr->name);
kfree(tr);

@@ -6097,6 +6100,9 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
{
int cpu;

+ trace_create_file("tracing_cpumask", 0644, d_tracer,
+ tr, &tracing_cpumask_fops);
+
trace_create_file("trace_options", 0644, d_tracer,
tr, &tracing_iter_fops);

@@ -6146,9 +6152,6 @@ static __init int tracer_init_debugfs(void)

init_tracer_debugfs(&global_trace, d_tracer);

- trace_create_file("tracing_cpumask", 0644, d_tracer,
- &global_trace, &tracing_cpumask_fops);
-
trace_create_file("available_tracers", 0444, d_tracer,
&global_trace, &show_traces_fops);

@@ -6370,7 +6373,7 @@ __init static int tracer_alloc_buffers(void)
if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
goto out;

- if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
+ if (!alloc_cpumask_var(&global_trace.tracing_cpumask, GFP_KERNEL))
goto out_free_buffer_mask;

/* Only allocate trace_printk buffers if a trace_printk exists */
@@ -6385,7 +6388,7 @@ __init static int tracer_alloc_buffers(void)
ring_buf_size = 1;

cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
- cpumask_copy(tracing_cpumask, cpu_all_mask);
+ cpumask_copy(global_trace.tracing_cpumask, cpu_all_mask);

raw_spin_lock_init(&global_trace.start_lock);

@@ -6440,7 +6443,7 @@ out_free_cpumask:
#ifdef CONFIG_TRACER_MAX_TRACE
free_percpu(global_trace.max_buffer.data);
#endif
- free_cpumask_var(tracing_cpumask);
+ free_cpumask_var(global_trace.tracing_cpumask);
out_free_buffer_mask:
free_cpumask_var(tracing_buffer_mask);
out:
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index afaae41..502fed7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -206,6 +206,7 @@ struct trace_array {
struct dentry *event_dir;
struct list_head systems;
struct list_head events;
+ cpumask_var_t tracing_cpumask; /* only trace on set CPUs */
int ref;
};

--
1.8.3


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