tracing: Prevent buffer overwrite disabled for latency tracers

[pandora-kernel.git] / kernel / trace / trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f2bd275..17edb14 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -652,7 +652,7 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 void
 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
-       struct ring_buffer *buf = tr->buffer;
+       struct ring_buffer *buf;
 
        if (trace_stop_count)
                return;
@@ -664,6 +664,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
        }
        arch_spin_lock(&ftrace_max_lock);
 
+       buf = tr->buffer;
        tr->buffer = max_tr.buffer;
        max_tr.buffer = buf;
 
@@ -1642,6 +1643,7 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
        int cpu_file = iter->cpu_file;
        u64 next_ts = 0, ts;
        int next_cpu = -1;
+       int next_size = 0;
        int cpu;
 
        /*
@@ -1673,9 +1675,12 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
                        next_cpu = cpu;
                        next_ts = ts;
                        next_lost = lost_events;
+                       next_size = iter->ent_size;
                }
        }
 
+       iter->ent_size = next_size;
+
        if (ent_cpu)
                *ent_cpu = next_cpu;
 
@@ -2537,10 +2542,12 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
                if (cpumask_test_cpu(cpu, tracing_cpumask) &&
                                !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
                        atomic_inc(&global_trace.data[cpu]->disabled);
+                       ring_buffer_record_disable_cpu(global_trace.buffer, cpu);
                }
                if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
                                cpumask_test_cpu(cpu, tracing_cpumask_new)) {
                        atomic_dec(&global_trace.data[cpu]->disabled);
+                       ring_buffer_record_enable_cpu(global_trace.buffer, cpu);
                }
        }
        arch_spin_unlock(&ftrace_max_lock);
@@ -2629,11 +2636,25 @@ static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
        return -EINVAL;
 }
 
-static void set_tracer_flags(unsigned int mask, int enabled)
+/* Some tracers require overwrite to stay enabled */
+int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
+{
+       if (tracer->enabled && (mask & TRACE_ITER_OVERWRITE) && !set)
+               return -1;
+
+       return 0;
+}
+
+int set_tracer_flag(unsigned int mask, int enabled)
 {
        /* do nothing if flag is already set */
        if (!!(trace_flags & mask) == !!enabled)
-               return;
+               return 0;
+
+       /* Give the tracer a chance to approve the change */
+       if (current_trace->flag_changed)
+               if (current_trace->flag_changed(current_trace, mask, !!enabled))
+                       return -EINVAL;
 
        if (enabled)
                trace_flags |= mask;
@@ -2643,8 +2664,14 @@ static void set_tracer_flags(unsigned int mask, int enabled)
        if (mask == TRACE_ITER_RECORD_CMD)
                trace_event_enable_cmd_record(enabled);
 
-       if (mask == TRACE_ITER_OVERWRITE)
+       if (mask == TRACE_ITER_OVERWRITE) {
                ring_buffer_change_overwrite(global_trace.buffer, enabled);
+#ifdef CONFIG_TRACER_MAX_TRACE
+               ring_buffer_change_overwrite(max_tr.buffer, enabled);
+#endif
+       }
+
+       return 0;
 }
 
 static ssize_t
@@ -2654,7 +2681,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
        char buf[64];
        char *cmp;
        int neg = 0;
-       int ret;
+       int ret = 0;
        int i;
 
        if (cnt >= sizeof(buf))
@@ -2671,21 +2698,23 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                cmp += 2;
        }
 
+       mutex_lock(&trace_types_lock);
+
        for (i = 0; trace_options[i]; i++) {
                if (strcmp(cmp, trace_options[i]) == 0) {
-                       set_tracer_flags(1 << i, !neg);
+                       ret = set_tracer_flag(1 << i, !neg);
                        break;
                }
        }
 
        /* If no option could be set, test the specific tracer options */
-       if (!trace_options[i]) {
-               mutex_lock(&trace_types_lock);
+       if (!trace_options[i])
                ret = set_tracer_option(current_trace, cmp, neg);
-               mutex_unlock(&trace_types_lock);
-               if (ret)
-                       return ret;
-       }
+
+       mutex_unlock(&trace_types_lock);
+
+       if (ret)
+               return ret;
 
        *ppos += cnt;
 
@@ -3009,6 +3038,9 @@ static int tracing_set_tracer(const char *buf)
                goto out;
 
        trace_branch_disable();
+
+       current_trace->enabled = false;
+
        if (current_trace && current_trace->reset)
                current_trace->reset(tr);
        if (current_trace && current_trace->use_max_tr) {
@@ -3038,6 +3070,7 @@ static int tracing_set_tracer(const char *buf)
                        goto out;
        }
 
+       current_trace->enabled = true;
        trace_branch_enable(tr);
  out:
        mutex_unlock(&trace_types_lock);
@@ -3452,6 +3485,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                .pages          = pages_def,
                .partial        = partial_def,
                .nr_pages       = 0, /* This gets updated below. */
+               .nr_pages_max   = PIPE_DEF_BUFFERS,
                .flags          = flags,
                .ops            = &tracing_pipe_buf_ops,
                .spd_release    = tracing_spd_release_pipe,
@@ -3523,7 +3557,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 
        ret = splice_to_pipe(pipe, &spd);
 out:
-       splice_shrink_spd(pipe, &spd);
+       splice_shrink_spd(&spd);
        return ret;
 
 out_err:
@@ -4013,6 +4047,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
        struct splice_pipe_desc spd = {
                .pages          = pages_def,
                .partial        = partial_def,
+               .nr_pages_max   = PIPE_DEF_BUFFERS,
                .flags          = flags,
                .ops            = &buffer_pipe_buf_ops,
                .spd_release    = buffer_spd_release,
@@ -4100,7 +4135,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
        }
 
        ret = splice_to_pipe(pipe, &spd);
-       splice_shrink_spd(pipe, &spd);
+       splice_shrink_spd(&spd);
 out:
        return ret;
 }
@@ -4370,7 +4405,13 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
        if (val != 0 && val != 1)
                return -EINVAL;
-       set_tracer_flags(1 << index, val);
+
+       mutex_lock(&trace_types_lock);
+       ret = set_tracer_flag(1 << index, val);
+       mutex_unlock(&trace_types_lock);
+
+       if (ret < 0)
+               return ret;
 
        *ppos += cnt;