tracing: fix config options to not show when automatically selected

There are two options that are selected by all tracers, but we want
to have those options available when no tracer is selected. These are

 The event tracer and sched switch tracer.

The are enabled by all tracers, but if a tracer is not selected we want
the options to appear. All tracers including them select TRACING.
Thus what we would like to do is:

  config EVENT_TRACER
	bool "prompt"
	depends on TRACING
	select TRACING

But that gives us a bug in the kbuild system since we just created a
circular dependency. We only want the prompt to show when TRACING is off.

This patch adds GENERIC_TRACER that all tracers will select instead of
TRACING. The two options (sched switch and event tracer) will select
TRACING directly and depend on !GENERIC_TRACER. This solves the cicular
dependency.

[ Impact: hide options that are selected by default ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 28 insertions, 15 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a508b9d2adb..6e55cc3ac49 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -56,6 +56,13 @@ config CONTEXT_SWITCH_TRACER
         select MARKERS
         bool
 
+# All tracer options should select GENERIC_TRACER. For those options that are
+# enabled by all tracers (context switch and event tracer) they select TRACING.
+# This allows those options to appear when no other tracer is selected. But the
+# options do not appear when something else selects it. We need the two options
+# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
+# hidding of the automatic options options.
+
 config TRACING
         bool
         select DEBUG_FS
@@ -66,6 +73,10 @@ config TRACING
         select BINARY_PRINTF
         select EVENT_TRACING
 
+config GENERIC_TRACER
+        bool
+        select TRACING
+
 #
 # Minimum requirements an architecture has to meet for us to
 # be able to offer generic tracing facilities:
@@ -95,7 +106,7 @@ config FUNCTION_TRACER
         depends on HAVE_FUNCTION_TRACER
         select FRAME_POINTER
         select KALLSYMS
-        select TRACING
+        select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
         help
           Enable the kernel to trace every kernel function. This is done
@@ -126,7 +137,7 @@ config IRQSOFF_TRACER
         depends on TRACE_IRQFLAGS_SUPPORT
         depends on GENERIC_TIME
         select TRACE_IRQFLAGS
-        select TRACING
+        select GENERIC_TRACER
         select TRACER_MAX_TRACE
         help
           This option measures the time spent in irqs-off critical
@@ -147,7 +158,7 @@ config PREEMPT_TRACER
         default n
         depends on GENERIC_TIME
         depends on PREEMPT
-        select TRACING
+        select GENERIC_TRACER
         select TRACER_MAX_TRACE
         help
           This option measures the time spent in preemption off critical
@@ -166,7 +177,7 @@ config PREEMPT_TRACER
 config SYSPROF_TRACER
         bool "Sysprof Tracer"
         depends on X86
-        select TRACING
+        select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
         help
           This tracer provides the trace needed by the 'Sysprof' userspace
@@ -174,7 +185,7 @@ config SYSPROF_TRACER
 
 config SCHED_TRACER
         bool "Scheduling Latency Tracer"
-        select TRACING
+        select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
         select TRACER_MAX_TRACE
         help
@@ -183,6 +194,7 @@ config SCHED_TRACER
 
 config ENABLE_CONTEXT_SWITCH_TRACER
         bool "Trace process context switches"
+        depends on !GENERIC_TRACER
         select TRACING
         select CONTEXT_SWITCH_TRACER
         help
@@ -191,6 +203,7 @@ config ENABLE_CONTEXT_SWITCH_TRACER
 
 config ENABLE_EVENT_TRACING
         bool "Trace various events in the kernel"
+        depends on !GENERIC_TRACER
         select TRACING
         help
           This tracer hooks to various trace points in the kernel
@@ -204,14 +217,14 @@ config ENABLE_EVENT_TRACING
 config FTRACE_SYSCALLS
         bool "Trace syscalls"
         depends on HAVE_FTRACE_SYSCALLS
-        select TRACING
+        select GENERIC_TRACER
         select KALLSYMS
         help
           Basic tracer to catch the syscall entry and exit events.
 
 config BOOT_TRACER
         bool "Trace boot initcalls"
-        select TRACING
+        select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
         help
           This tracer helps developers to optimize boot times: it records
@@ -228,7 +241,7 @@ config BOOT_TRACER
 
 config TRACE_BRANCH_PROFILING
         bool
-        select TRACING
+        select GENERIC_TRACER
 
 choice
         prompt "Branch Profiling"
@@ -308,7 +321,7 @@ config BRANCH_TRACER
 config POWER_TRACER
         bool "Trace power consumption behavior"
         depends on X86
-        select TRACING
+        select GENERIC_TRACER
         help
           This tracer helps developers to analyze and optimize the kernels
           power management decisions, specifically the C-state and P-state
@@ -342,14 +355,14 @@ config STACK_TRACER
 config HW_BRANCH_TRACER
         depends on HAVE_HW_BRANCH_TRACER
         bool "Trace hw branches"
-        select TRACING
+        select GENERIC_TRACER
         help
           This tracer records all branches on the system in a circular
           buffer giving access to the last N branches for each cpu.
 
 config KMEMTRACE
         bool "Trace SLAB allocations"
-        select TRACING
+        select GENERIC_TRACER
         help
           kmemtrace provides tracing for slab allocator functions, such as
           kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
@@ -369,7 +382,7 @@ config KMEMTRACE
 
 config WORKQUEUE_TRACER
         bool "Trace workqueues"
-        select TRACING
+        select GENERIC_TRACER
         help
           The workqueue tracer provides some statistical informations
           about each cpu workqueue thread such as the number of the
@@ -385,7 +398,7 @@ config BLK_DEV_IO_TRACE
         select RELAY
         select DEBUG_FS
         select TRACEPOINTS
-        select TRACING
+        select GENERIC_TRACER
         select STACKTRACE
         help
           Say Y here if you want to be able to trace the block layer actions
@@ -446,7 +459,7 @@ config FTRACE_SELFTEST
 
 config FTRACE_STARTUP_TEST
         bool "Perform a startup test on ftrace"
-        depends on TRACING
+        depends on GENERIC_TRACER
         select FTRACE_SELFTEST
         help
           This option performs a series of startup tests on ftrace. On bootup
@@ -457,7 +470,7 @@ config FTRACE_STARTUP_TEST
 config MMIOTRACE
         bool "Memory mapped IO tracing"
         depends on HAVE_MMIOTRACE_SUPPORT && PCI
-        select TRACING
+        select GENERIC_TRACER
         help
           Mmiotrace traces Memory Mapped I/O access and is meant for
           debugging and reverse engineering. It is called from the ioremap