tracing: Make tracing_cpumask available for all instances

Allow tracer instances to disable tracing by cpu by moving
the static global tracing_cpumask into trace_array.

Link: http://lkml.kernel.org/r/921622317f239bfc2283cac2242647801ef584f2.1375980149.git.azl@google.com

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>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 21 insertions, 17 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 496f94d57698..7974ba20557d 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,
 };
 
@@ -5938,6 +5935,11 @@ 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;
@@ -5969,6 +5971,7 @@ 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);
 
@@ -6098,6 +6101,9 @@ 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);
 
@@ -6147,9 +6153,6 @@ 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);
 
@@ -6371,7 +6374,7 @@ __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 */
@@ -6386,7 +6389,7 @@ __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);
 
@@ -6441,7 +6444,7 @@ 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 afaae41b0a02..502fed770751 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;
 };