3 files changed, 205 insertions, 80 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4a39d24568c8..78db083390f0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -185,7 +185,6 @@ enum {
 };
 
 static int ftrace_filtered;
-static int tracing_on;
 
 static LIST_HEAD(ftrace_new_addrs);
 
@@ -327,96 +326,89 @@ ftrace_record_ip(unsigned long ip)
 
 static int
 __ftrace_replace_code(struct dyn_ftrace *rec,
-                      unsigned char *old, unsigned char *new, int enable)
+                      unsigned char *nop, int enable)
 {
         unsigned long ip, fl;
+        unsigned char *call, *old, *new;
 
         ip = rec->ip;
 
-        if (ftrace_filtered && enable) {
+        /*
+         * If this record is not to be traced and
+         * it is not enabled then do nothing.
+         *
+         * If this record is not to be traced and
+         * it is enabled then disabled it.
+         *
+         */
+        if (rec->flags & FTRACE_FL_NOTRACE) {
+                if (rec->flags & FTRACE_FL_ENABLED)
+                        rec->flags &= ~FTRACE_FL_ENABLED;
+                else
+                        return 0;
+
+        } else if (ftrace_filtered && enable) {
                 /*
-                 * If filtering is on:
-                 *
-                 * If this record is set to be filtered and
-                 * is enabled then do nothing.
-                 *
-                 * If this record is set to be filtered and
-                 * it is not enabled, enable it.
-                 *
-                 * If this record is not set to be filtered
-                 * and it is not enabled do nothing.
-                 *
-                 * If this record is set not to trace then
-                 * do nothing.
-                 *
-                 * If this record is set not to trace and
-                 * it is enabled then disable it.
-                 *
-                 * If this record is not set to be filtered and
-                 * it is enabled, disable it.
+                 * Filtering is on:
                  */
 
-                fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE |
-                                   FTRACE_FL_ENABLED);
+                fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
 
-                if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
-                    (fl ==  (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE)) ||
-                    !fl || (fl == FTRACE_FL_NOTRACE))
+                /* Record is filtered and enabled, do nothing */
+                if (fl == (FTRACE_FL_FILTER | FTRACE_FL_ENABLED))
                         return 0;
 
-                /*
-                 * If it is enabled disable it,
-                 * otherwise enable it!
-                 */
-                if (fl & FTRACE_FL_ENABLED) {
-                        /* swap new and old */
-                        new = old;
-                        old = ftrace_call_replace(ip, FTRACE_ADDR);
+                /* Record is not filtered and is not enabled do nothing */
+                if (!fl)
+                        return 0;
+
+                /* Record is not filtered but enabled, disable it */
+                if (fl == FTRACE_FL_ENABLED)
                         rec->flags &= ~FTRACE_FL_ENABLED;
-                } else {
-                        new = ftrace_call_replace(ip, FTRACE_ADDR);
+                else
+                /* Otherwise record is filtered but not enabled, enable it */
                         rec->flags |= FTRACE_FL_ENABLED;
-                }
         } else {
+                /* Disable or not filtered */
 
                 if (enable) {
-                        /*
-                         * If this record is set not to trace and is
-                         * not enabled, do nothing.
-                         */
-                        fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
-                        if (fl == FTRACE_FL_NOTRACE)
-                                return 0;
-
-                        new = ftrace_call_replace(ip, FTRACE_ADDR);
-                } else
-                        old = ftrace_call_replace(ip, FTRACE_ADDR);
-
-                if (enable) {
+                        /* if record is enabled, do nothing */
                         if (rec->flags & FTRACE_FL_ENABLED)
                                 return 0;
+
                         rec->flags |= FTRACE_FL_ENABLED;
+
                 } else {
+
+                        /* if record is not enabled do nothing */
                         if (!(rec->flags & FTRACE_FL_ENABLED))
                                 return 0;
+
                         rec->flags &= ~FTRACE_FL_ENABLED;
                 }
         }
 
+        call = ftrace_call_replace(ip, FTRACE_ADDR);
+
+        if (rec->flags & FTRACE_FL_ENABLED) {
+                old = nop;
+                new = call;
+        } else {
+                old = call;
+                new = nop;
+        }
+
         return ftrace_modify_code(ip, old, new);
 }
 
 static void ftrace_replace_code(int enable)
 {
         int i, failed;
-        unsigned char *new = NULL, *old = NULL;
+        unsigned char *nop = NULL;
         struct dyn_ftrace *rec;
         struct ftrace_page *pg;
 
-        if (enable)
-                old = ftrace_nop_replace();
-        else
-                new = ftrace_nop_replace();
+        nop = ftrace_nop_replace();
 
         for (pg = ftrace_pages_start; pg; pg = pg->next) {
                 for (i = 0; i < pg->index; i++) {
@@ -434,7 +426,7 @@ static void ftrace_replace_code(int enable)
                                 unfreeze_record(rec);
                         }
 
-                        failed = __ftrace_replace_code(rec, old, new, enable);
+                        failed = __ftrace_replace_code(rec, nop, enable);
                         if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
                                 rec->flags |= FTRACE_FL_FAILED;
                                 if ((system_state == SYSTEM_BOOTING) ||
@@ -506,13 +498,10 @@ static int __ftrace_modify_code(void *data)
 {
         int *command = data;
 
-        if (*command & FTRACE_ENABLE_CALLS) {
+        if (*command & FTRACE_ENABLE_CALLS)
                 ftrace_replace_code(1);
-                tracing_on = 1;
-        } else if (*command & FTRACE_DISABLE_CALLS) {
+        else if (*command & FTRACE_DISABLE_CALLS)
                 ftrace_replace_code(0);
-                tracing_on = 0;
-        }
 
         if (*command & FTRACE_UPDATE_TRACE_FUNC)
                 ftrace_update_ftrace_func(ftrace_trace_function);
@@ -538,8 +527,7 @@ static void ftrace_startup(void)
 
         mutex_lock(&ftrace_start_lock);
         ftrace_start++;
-        if (ftrace_start == 1)
-                command |= FTRACE_ENABLE_CALLS;
+        command |= FTRACE_ENABLE_CALLS;
 
         if (saved_ftrace_func != ftrace_trace_function) {
                 saved_ftrace_func = ftrace_trace_function;
@@ -677,7 +665,7 @@ static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
 
         cnt = num_to_init / ENTRIES_PER_PAGE;
         pr_info("ftrace: allocating %ld entries in %d pages\n",
-                num_to_init, cnt);
+                num_to_init, cnt + 1);
 
         for (i = 0; i < cnt; i++) {
                 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
@@ -738,6 +726,9 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                     ((iter->flags & FTRACE_ITER_FAILURES) &&
                      !(rec->flags & FTRACE_FL_FAILED)) ||
 
+                    ((iter->flags & FTRACE_ITER_FILTER) &&
+                     !(rec->flags & FTRACE_FL_FILTER)) ||
+
                     ((iter->flags & FTRACE_ITER_NOTRACE) &&
                      !(rec->flags & FTRACE_FL_NOTRACE))) {
                         rec = NULL;
@@ -757,13 +748,11 @@ static void *t_start(struct seq_file *m, loff_t *pos)
         void *p = NULL;
         loff_t l = -1;
 
-        if (*pos != iter->pos) {
-                for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
-                        ;
-        } else {
-                l = *pos;
-                p = t_next(m, p, &l);
-        }
+        if (*pos > iter->pos)
+                *pos = iter->pos;
+
+        l = *pos;
+        p = t_next(m, p, &l);
 
         return p;
 }
@@ -774,15 +763,21 @@ static void t_stop(struct seq_file *m, void *p)
 
 static int t_show(struct seq_file *m, void *v)
 {
+        struct ftrace_iterator *iter = m->private;
         struct dyn_ftrace *rec = v;
         char str[KSYM_SYMBOL_LEN];
+        int ret = 0;
 
         if (!rec)
                 return 0;
 
         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 
-        seq_printf(m, "%s\n", str);
+        ret = seq_printf(m, "%s\n", str);
+        if (ret < 0) {
+                iter->pos--;
+                iter->idx--;
+        }
 
         return 0;
 }
@@ -808,7 +803,7 @@ ftrace_avail_open(struct inode *inode, struct file *file)
                 return -ENOMEM;
 
         iter->pg = ftrace_pages_start;
-        iter->pos = -1;
+        iter->pos = 0;
 
         ret = seq_open(file, &show_ftrace_seq_ops);
         if (!ret) {
@@ -895,7 +890,7 @@ ftrace_regex_open(struct inode *inode, struct file *file, int enable)
 
         if (file->f_mode & FMODE_READ) {
                 iter->pg = ftrace_pages_start;
-                iter->pos = -1;
+                iter->pos = 0;
                 iter->flags = enable ? FTRACE_ITER_FILTER :
                         FTRACE_ITER_NOTRACE;
 
@@ -1186,7 +1181,7 @@ ftrace_regex_release(struct inode *inode, struct file *file, int enable)
 
         mutex_lock(&ftrace_sysctl_lock);
         mutex_lock(&ftrace_start_lock);
-        if (iter->filtered && ftrace_start && ftrace_enabled)
+        if (ftrace_start && ftrace_enabled)
                 ftrace_run_update_code(FTRACE_ENABLE_CALLS);
         mutex_unlock(&ftrace_start_lock);
         mutex_unlock(&ftrace_sysctl_lock);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 3f3380638646..f780e9552f91 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -16,14 +16,49 @@
 #include <linux/list.h>
 #include <linux/fs.h>
 
+#include "trace.h"
+
+/* Global flag to disable all recording to ring buffers */
+static int ring_buffers_off __read_mostly;
+
+/**
+ * tracing_on - enable all tracing buffers
+ *
+ * This function enables all tracing buffers that may have been
+ * disabled with tracing_off.
+ */
+void tracing_on(void)
+{
+        ring_buffers_off = 0;
+}
+
+/**
+ * tracing_off - turn off all tracing buffers
+ *
+ * This function stops all tracing buffers from recording data.
+ * It does not disable any overhead the tracers themselves may
+ * be causing. This function simply causes all recording to
+ * the ring buffers to fail.
+ */
+void tracing_off(void)
+{
+        ring_buffers_off = 1;
+}
+
 /* Up this if you want to test the TIME_EXTENTS and normalization */
 #define DEBUG_SHIFT 0
 
 /* FIXME!!! */
 u64 ring_buffer_time_stamp(int cpu)
 {
+        u64 time;
+
+        preempt_disable_notrace();
         /* shift to debug/test normalization and TIME_EXTENTS */
-        return sched_clock() << DEBUG_SHIFT;
+        time = sched_clock() << DEBUG_SHIFT;
+        preempt_enable_notrace();
+
+        return time;
 }
 
 void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)
@@ -503,6 +538,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
         LIST_HEAD(pages);
         int i, cpu;
 
+        /*
+         * Always succeed at resizing a non-existent buffer:
+         */
+        if (!buffer)
+                return size;
+
         size = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
         size *= BUF_PAGE_SIZE;
         buffer_size = buffer->pages * BUF_PAGE_SIZE;
@@ -576,6 +617,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
                 list_del_init(&page->list);
                 free_buffer_page(page);
         }
+        mutex_unlock(&buffer->mutex);
         return -ENOMEM;
 }
 
@@ -1060,7 +1102,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
 
                 /* Did the write stamp get updated already? */
                 if (unlikely(ts < cpu_buffer->write_stamp))
-                        goto again;
+                        delta = 0;
 
                 if (test_time_stamp(delta)) {
 
@@ -1133,6 +1175,9 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer,
         struct ring_buffer_event *event;
         int cpu, resched;
 
+        if (ring_buffers_off)
+                return NULL;
+
         if (atomic_read(&buffer->record_disabled))
                 return NULL;
 
@@ -1249,6 +1294,9 @@ int ring_buffer_write(struct ring_buffer *buffer,
         int ret = -EBUSY;
         int cpu, resched;
 
+        if (ring_buffers_off)
+                return -EBUSY;
+
         if (atomic_read(&buffer->record_disabled))
                 return -EBUSY;
 
@@ -2070,3 +2118,69 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
         return 0;
 }
 
+static ssize_t
+rb_simple_read(struct file *filp, char __user *ubuf,
+               size_t cnt, loff_t *ppos)
+{
+        int *p = filp->private_data;
+        char buf[64];
+        int r;
+
+        /* !ring_buffers_off == tracing_on */
+        r = sprintf(buf, "%d\n", !*p);
+
+        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+rb_simple_write(struct file *filp, const char __user *ubuf,
+                size_t cnt, loff_t *ppos)
+{
+        int *p = filp->private_data;
+        char buf[64];
+        long val;
+        int ret;
+
+        if (cnt >= sizeof(buf))
+                return -EINVAL;
+
+        if (copy_from_user(&buf, ubuf, cnt))
+                return -EFAULT;
+
+        buf[cnt] = 0;
+
+        ret = strict_strtoul(buf, 10, &val);
+        if (ret < 0)
+                return ret;
+
+        /* !ring_buffers_off == tracing_on */
+        *p = !val;
+
+        (*ppos)++;
+
+        return cnt;
+}
+
+static struct file_operations rb_simple_fops = {
+        .open           = tracing_open_generic,
+        .read           = rb_simple_read,
+        .write          = rb_simple_write,
+};
+
+
+static __init int rb_init_debugfs(void)
+{
+        struct dentry *d_tracer;
+        struct dentry *entry;
+
+        d_tracer = tracing_init_dentry();
+
+        entry = debugfs_create_file("tracing_on", 0644, d_tracer,
+                                    &ring_buffers_off, &rb_simple_fops);
+        if (!entry)
+                pr_warning("Could not create debugfs 'tracing_on' entry\n");
+
+        return 0;
+}
+
+fs_initcall(rb_init_debugfs);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9f3b478f9171..d86e3252f300 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1755,7 +1755,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
                 return TRACE_TYPE_HANDLED;
 
         SEQ_PUT_FIELD_RET(s, entry->pid);
-        SEQ_PUT_FIELD_RET(s, iter->cpu);
+        SEQ_PUT_FIELD_RET(s, entry->cpu);
         SEQ_PUT_FIELD_RET(s, iter->ts);
 
         switch (entry->type) {
@@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
                         ring_buffer_read_finish(iter->buffer_iter[cpu]);
         }
         mutex_unlock(&trace_types_lock);
+        kfree(iter);
 
         return ERR_PTR(-ENOMEM);
 }
@@ -2676,7 +2677,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 {
         unsigned long val;
         char buf[64];
-        int ret;
+        int ret, cpu;
         struct trace_array *tr = filp->private_data;
 
         if (cnt >= sizeof(buf))
@@ -2704,6 +2705,14 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
                 goto out;
         }
 
+        /* disable all cpu buffers */
+        for_each_tracing_cpu(cpu) {
+                if (global_trace.data[cpu])
+                        atomic_inc(&global_trace.data[cpu]->disabled);
+                if (max_tr.data[cpu])
+                        atomic_inc(&max_tr.data[cpu]->disabled);
+        }
+
         if (val != global_trace.entries) {
                 ret = ring_buffer_resize(global_trace.buffer, val);
                 if (ret < 0) {
@@ -2735,6 +2744,13 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
         if (tracing_disabled)
                 cnt = -ENOMEM;
  out:
+        for_each_tracing_cpu(cpu) {
+                if (global_trace.data[cpu])
+                        atomic_dec(&global_trace.data[cpu]->disabled);
+                if (max_tr.data[cpu])
+                        atomic_dec(&max_tr.data[cpu]->disabled);
+        }
+
         max_tr.entries = global_trace.entries;
         mutex_unlock(&trace_types_lock);