cpumask: convert kernel trace functions

Impact: Reduce future memory usage, use new cpumask API.

(Eventually, cpumask_var_t will be allocated based on nr_cpu_ids, not NR_CPUS).

Convert kernel trace functions to use struct cpumask API:
1) Use cpumask_copy/cpumask_test_cpu/for_each_cpu.
2) Use cpumask_var_t and alloc_cpumask_var/free_cpumask_var everywhere.
3) Use on_each_cpu instead of playing with current->cpus_allowed.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 36 insertions, 24 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0e91f43..5d04e27 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -89,10 +89,10 @@ static inline void ftrace_enable_cpu(void)
 	preempt_enable();
 }
 
-static cpumask_t __read_mostly		tracing_buffer_mask;
+static cpumask_var_t __read_mostly	tracing_buffer_mask;
 
 #define for_each_tracing_cpu(cpu)	\
-	for_each_cpu_mask(cpu, tracing_buffer_mask)
+	for_each_cpu(cpu, tracing_buffer_mask)
 
 /*
  * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
@@ -2646,13 +2646,7 @@ static struct file_operations show_traces_fops = {
 /*
  * Only trace on a CPU if the bitmask is set:
  */
-static cpumask_t tracing_cpumask = CPU_MASK_ALL;
-
-/*
- * When tracing/tracing_cpu_mask is modified then this holds
- * the new bitmask we are about to install:
- */
-static cpumask_t tracing_cpumask_new;
+static cpumask_var_t tracing_cpumask;
 
 /*
  * The tracer itself will not take this lock, but still we want
@@ -2674,7 +2668,7 @@ tracing_cpumask_read(struct file *filp, char __user *ubuf,
 
 	mutex_lock(&tracing_cpumask_update_lock);
 
-	len = cpumask_scnprintf(mask_str, count, &tracing_cpumask);
+	len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
 	if (count - len < 2) {
 		count = -EINVAL;
 		goto out_err;
@@ -2693,9 +2687,13 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 		      size_t count, loff_t *ppos)
 {
 	int err, cpu;
+	cpumask_var_t tracing_cpumask_new;
+
+	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
+		return -ENOMEM;
 
 	mutex_lock(&tracing_cpumask_update_lock);
-	err = cpumask_parse_user(ubuf, count, &tracing_cpumask_new);
+	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
 	if (err)
 		goto err_unlock;
 
@@ -2706,26 +2704,28 @@ 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 (cpu_isset(cpu, tracing_cpumask) &&
-				!cpu_isset(cpu, tracing_cpumask_new)) {
+		if (cpumask_test_cpu(cpu, tracing_cpumask) &&
+				!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
 			atomic_inc(&global_trace.data[cpu]->disabled);
 		}
-		if (!cpu_isset(cpu, tracing_cpumask) &&
-				cpu_isset(cpu, tracing_cpumask_new)) {
+		if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
+				cpumask_test_cpu(cpu, tracing_cpumask_new)) {
 			atomic_dec(&global_trace.data[cpu]->disabled);
 		}
 	}
 	__raw_spin_unlock(&ftrace_max_lock);
 	local_irq_enable();
 
-	tracing_cpumask = tracing_cpumask_new;
+	cpumask_copy(tracing_cpumask, tracing_cpumask_new);
 
 	mutex_unlock(&tracing_cpumask_update_lock);
+	free_cpumask_var(tracing_cpumask_new);
 
 	return count;
 
 err_unlock:
 	mutex_unlock(&tracing_cpumask_update_lock);
+	free_cpumask_var(tracing_cpumask);
 
 	return err;
 }
@@ -3752,7 +3752,6 @@ void ftrace_dump(void)
 	static DEFINE_SPINLOCK(ftrace_dump_lock);
 	/* use static because iter can be a bit big for the stack */
 	static struct trace_iterator iter;
-	static cpumask_t mask;
 	static int dump_ran;
 	unsigned long flags;
 	int cnt = 0, cpu;
@@ -3786,8 +3785,6 @@ void ftrace_dump(void)
 	 * and then release the locks again.
 	 */
 
-	cpus_clear(mask);
-
 	while (!trace_empty(&iter)) {
 
 		if (!cnt)
@@ -3823,19 +3820,28 @@ __init static int tracer_alloc_buffers(void)
 {
 	struct trace_array_cpu *data;
 	int i;
+	int ret = -ENOMEM;
 
-	/* TODO: make the number of buffers hot pluggable with CPUS */
-	tracing_buffer_mask = cpu_possible_map;
+	if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
+		goto out;
+
+	if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
+		goto out_free_buffer_mask;
 
+	cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
+	cpumask_copy(tracing_cpumask, cpu_all_mask);
+
+	/* TODO: make the number of buffers hot pluggable with CPUS */
 	global_trace.buffer = ring_buffer_alloc(trace_buf_size,
 						   TRACE_BUFFER_FLAGS);
 	if (!global_trace.buffer) {
 		printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
 		WARN_ON(1);
-		return 0;
+		goto out_free_cpumask;
 	}
 	global_trace.entries = ring_buffer_size(global_trace.buffer);
 
+
 #ifdef CONFIG_TRACER_MAX_TRACE
 	max_tr.buffer = ring_buffer_alloc(trace_buf_size,
 					     TRACE_BUFFER_FLAGS);
@@ -3843,7 +3849,7 @@ __init static int tracer_alloc_buffers(void)
 		printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
 		WARN_ON(1);
 		ring_buffer_free(global_trace.buffer);
-		return 0;
+		goto out_free_cpumask;
 	}
 	max_tr.entries = ring_buffer_size(max_tr.buffer);
 	WARN_ON(max_tr.entries != global_trace.entries);
@@ -3873,8 +3879,14 @@ __init static int tracer_alloc_buffers(void)
 				       &trace_panic_notifier);
 
 	register_die_notifier(&trace_die_notifier);
+	ret = 0;
 
-	return 0;
+out_free_cpumask:
+	free_cpumask_var(tracing_cpumask);
+out_free_buffer_mask:
+	free_cpumask_var(tracing_buffer_mask);
+out:
+	return ret;
 }
 early_initcall(tracer_alloc_buffers);
 fs_initcall(tracer_init_debugfs);