[PATCH] hw-breakpoint: Fix hardware breakpoints -> perf events dependency

[Frederic Weisbecker <fweisbec@gmail.com>]

The kbuild's select command doesn't propagate through the config
dependencies.

Hence the current rules of hardware breakpoint's config can't
ensure perf can never be disabled under us.

We have:

config X86
	selects HAVE_HW_BREAKPOINTS

config HAVE_HW_BREAKPOINTS
	select PERF_EVENTS

config PERF_EVENTS
	[...]

x86 will select the breakpoints but that won't propagate to perf
events. The user can still disable the latter, but it is necessary
for the breakpoints.

What we need is:

- x86 selects HAVE_HW_BREAKPOINTS and PERF_EVENTS
- HAVE_HW_BREAKPOINTS depends on PERF_EVENTS

so that we ensure PERF_EVENTS is enabled and frozen for x86.

This fixes the following kind of build errors:

In file included from arch/x86/kernel/hw_breakpoint.c:31:
include/linux/hw_breakpoint.h: In function 'hw_breakpoint_addr':
include/linux/hw_breakpoint.h:39: error: 'struct perf_event' has no member named 'attr'
include/linux/hw_breakpoint.h: In function 'hw_breakpoint_type':
include/linux/hw_breakpoint.h:44: error: 'struct perf_event' has no member named 'attr'
include/linux/hw_breakpoint.h: In function 'hw_breakpoint_len':
include/linux/hw_breakpoint.h:49: error: 'struct perf_event' has no member named 'attr'
include/linux/hw_breakpoint.h: In function 'counter_arch_bp':
include/linux/hw_breakpoint.h:85: error: 'struct perf_event' has no member named 'hw'

Reported-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Michal Marek <mmarek@suse.cz>
Reported-by: Andrew Randrianasulu <randrik_a@yahoo.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
---
 arch/Kconfig     |    4 +---
 arch/x86/Kconfig |    1 +
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 28146cd..32e8b68 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -138,9 +138,7 @@ config HAVE_USER_RETURN_NOTIFIER
 
 config HAVE_HW_BREAKPOINT
 	bool
-	depends on HAVE_PERF_EVENTS
-	select ANON_INODES
-	select PERF_EVENTS
+	depends on PERF_EVENTS
 
 
 source "kernel/gcov/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 098f0d3..ffbefd9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -50,6 +50,7 @@ config X86
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_LZMA
 	select HAVE_HW_BREAKPOINT
+	select PERF_EVENTS
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_USER_RETURN_NOTIFIER
 
-- 
1.6.2.3