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 0e91f43b6baf..5d04e27f3b40 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);