2 files changed, 112 insertions, 6 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2596b5a968c4..9531fddcfb8d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -43,6 +43,20 @@
 unsigned long __read_mostly     tracing_max_latency = (cycle_t)ULONG_MAX;
 unsigned long __read_mostly     tracing_thresh;
 
+/* For tracers that don't implement custom flags */
+static struct tracer_opt dummy_tracer_opt[] = {
+        { }
+};
+
+static struct tracer_flags dummy_tracer_flags = {
+        .val = 0,
+        .opts = dummy_tracer_opt
+};
+
+static int dummy_set_flag(u32 old_flags, u32 bit, int set)
+{
+        return 0;
+}
 
 /*
  * Kill all tracing for good (never come back).
@@ -529,6 +543,14 @@ int register_tracer(struct tracer *type)
                 }
         }
 
+        if (!type->set_flag)
+                type->set_flag = &dummy_set_flag;
+        if (!type->flags)
+                type->flags = &dummy_tracer_flags;
+        else
+                if (!type->flags->opts)
+                        type->flags->opts = dummy_tracer_opt;
+
 #ifdef CONFIG_FTRACE_STARTUP_TEST
         if (type->selftest) {
                 struct tracer *saved_tracer = current_trace;
@@ -2426,10 +2448,13 @@ static ssize_t
 tracing_trace_options_read(struct file *filp, char __user *ubuf,
                        size_t cnt, loff_t *ppos)
 {
+        int i;
         char *buf;
         int r = 0;
         int len = 0;
-        int i;
+        u32 tracer_flags = current_trace->flags->val;
+        struct tracer_opt *trace_opts = current_trace->flags->opts;
+
 
         /* calulate max size */
         for (i = 0; trace_options[i]; i++) {
@@ -2437,6 +2462,15 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
                 len += 3; /* "no" and space */
         }
 
+        /*
+         * Increase the size with names of options specific
+         * of the current tracer.
+         */
+        for (i = 0; trace_opts[i].name; i++) {
+                len += strlen(trace_opts[i].name);
+                len += 3; /* "no" and space */
+        }
+
         /* +2 for \n and \0 */
         buf = kmalloc(len + 2, GFP_KERNEL);
         if (!buf)
@@ -2449,6 +2483,15 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
                         r += sprintf(buf + r, "no%s ", trace_options[i]);
         }
 
+        for (i = 0; trace_opts[i].name; i++) {
+                if (tracer_flags & trace_opts[i].bit)
+                        r += sprintf(buf + r, "%s ",
+                                trace_opts[i].name);
+                else
+                        r += sprintf(buf + r, "no%s ",
+                                trace_opts[i].name);
+        }
+
         r += sprintf(buf + r, "\n");
         WARN_ON(r >= len + 2);
 
@@ -2459,6 +2502,40 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
         return r;
 }
 
+/* Try to assign a tracer specific option */
+static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
+{
+        struct tracer_flags *trace_flags = trace->flags;
+        struct tracer_opt *opts = NULL;
+        int ret = 0, i = 0;
+        int len;
+
+        for (i = 0; trace_flags->opts[i].name; i++) {
+                opts = &trace_flags->opts[i];
+                len = strlen(opts->name);
+
+                if (strncmp(cmp, opts->name, len) == 0) {
+                        ret = trace->set_flag(trace_flags->val,
+                                opts->bit, !neg);
+                        break;
+                }
+        }
+        /* Not found */
+        if (!trace_flags->opts[i].name)
+                return -EINVAL;
+
+        /* Refused to handle */
+        if (ret)
+                return ret;
+
+        if (neg)
+                trace_flags->val &= ~opts->bit;
+        else
+                trace_flags->val |= opts->bit;
+
+        return 0;
+}
+
 static ssize_t
 tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                         size_t cnt, loff_t *ppos)
@@ -2466,6 +2543,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
         char buf[64];
         char *cmp = buf;
         int neg = 0;
+        int ret;
         int i;
 
         if (cnt >= sizeof(buf))
@@ -2492,11 +2570,13 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                         break;
                 }
         }
-        /*
-         * If no option could be set, return an error:
-         */
-        if (!trace_options[i])
-                return -EINVAL;
+
+        /* If no option could be set, test the specific tracer options */
+        if (!trace_options[i]) {
+                ret = set_tracer_option(current_trace, cmp, neg);
+                if (ret)
+                        return ret;
+        }
 
         filp->f_pos += cnt;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 37947f6b92bf..9d22618bf99f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -259,6 +259,29 @@ enum print_line_t {
         TRACE_TYPE_UNHANDLED    = 2     /* Relay to other output functions */
 };
 
+
+/*
+ * An option specific to a tracer. This is a boolean value.
+ * The bit is the bit index that sets its value on the
+ * flags value in struct tracer_flags.
+ */
+struct tracer_opt {
+        const char      *name; /* Will appear on the trace_options file */
+        u32             bit; /* Mask assigned in val field in tracer_flags */
+};
+
+/*
+ * The set of specific options for a tracer. Your tracer
+ * have to set the initial value of the flags val.
+ */
+struct tracer_flags {
+        u32                     val;
+        struct tracer_opt       *opts;
+};
+
+/* Makes more easy to define a tracer opt */
+#define TRACER_OPT(s, b)        .name = #s, .bit = b
+
 /*
  * A specific tracer, represented by methods that operate on a trace array:
  */
@@ -280,8 +303,11 @@ struct tracer {
                                             struct trace_array *tr);
 #endif
         enum print_line_t       (*print_line)(struct trace_iterator *iter);
+        /* If you handled the flag setting, return 0 */
+        int                     (*set_flag)(u32 old_flags, u32 bit, int set);
         struct tracer           *next;
         int                     print_max;
+        struct tracer_flags     *flags;
 };
 
 struct trace_seq {