[PATCH] x86/kexec: crash_vmclear_local_vmcss needs __rcu

[Zhang Yanfei]

This removes the sparse warning:
arch/x86/kernel/crash.c:49:32: sparse: incompatible types in comparison expression (different address spaces)

Reported-by: kbuild test robot <fengguang.wu at intel.com>
Signed-off-by: Zhang Yanfei <zhangyanfei at cn.fujitsu.com>
---
 arch/x86/include/asm/kexec.h |    4 +++-
 arch/x86/kernel/crash.c      |    4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 28feeba..16882cd 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -163,7 +163,9 @@ struct kimage_arch {
 };
 #endif
 
-extern void (*crash_vmclear_loaded_vmcss)(void);
+extern void __rcu (*crash_vmclear_loaded_vmcss)(void);
+#define vmclear_func_rcu(vmclear_func) \
+	((void (*)(void)) rcu_dereference(vmclear_func))
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2f6b8e8..50ce1d6 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -38,7 +38,7 @@ int in_crash_kexec;
  *
  * protected by rcu.
  */
-void (*crash_vmclear_loaded_vmcss)(void) = NULL;
+void __rcu (*crash_vmclear_loaded_vmcss)(void) = NULL;
 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
 
 static inline void cpu_crash_vmclear_loaded_vmcss(void)
@@ -46,7 +46,7 @@ static inline void cpu_crash_vmclear_loaded_vmcss(void)
 	void (*do_vmclear_operation)(void) = NULL;
 
 	rcu_read_lock();
-	do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
+	do_vmclear_operation = vmclear_func_rcu(crash_vmclear_loaded_vmcss);
 	if (do_vmclear_operation)
 		do_vmclear_operation();
 	rcu_read_unlock();
-- 
1.7.1