Re: [PATCH ] x86 : Fix compilation warning on paravirt-spinlocks.c

[Ingo Molnar <mingo@elte.hu>]

* Rakib Mullick <rakib.mullick@gmail.com> wrote:

> Impact: Fix compilation warning.
> 
>  CC      arch/x86/kernel/paravirt-spinlocks.o
> arch/x86/kernel/paravirt-spinlocks.c: In function `default_spin_lock_flags':
> arch/x86/kernel/paravirt-spinlocks.c:12: warning: passing arg 1 of
> `__raw_spin_lock' from incompatible pointer type
> 
> This patch fixes the above warning.  __raw_spin_lock(lock) is declared
> when CONFIG_SMP is defined. Thus, a call to __raw_spin_lock requires
> checking CONFIG_SMP is defined or not.
> 
> Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
> 
> --- linux-2.6-orig/arch/x86/kernel/paravirt-spinlocks.c	2008-12-05
> 19:53:15.000000000 +0600
> +++ linux-2.6/arch/x86/kernel/paravirt-spinlocks.c	2008-12-07
> 23:52:59.000000000 +0600
> @@ -9,7 +9,9 @@
> 
>  static void default_spin_lock_flags(struct raw_spinlock *lock,
> unsigned long flags)
>  {
> +#ifdef	CONFIG_SMP
>  	__raw_spin_lock(lock);
> +#endif

no - this just works around the compiler warning.

Look at the real fix below i did some time ago. If you are into fixing 
warnings you should try tip/master, that has a ton of warning fixes 
already:

  http://people.redhat.com/mingo/tip.git/README

	Ingo

------------------------>
>From ecd05381e26b9a61e49fa485baea1595bd3d1b40 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 17 Oct 2008 16:09:57 +0200
Subject: [PATCH] x86: fix default_spin_lock_flags() prototype
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit

these warnings:

  arch/x86/kernel/paravirt-spinlocks.c: In function ‘default_spin_lock_flags’:
  arch/x86/kernel/paravirt-spinlocks.c:12: warning: passing argument 1 of ‘__raw_spin_lock’ from incompatible pointer type
  arch/x86/kernel/paravirt-spinlocks.c: At top level:
  arch/x86/kernel/paravirt-spinlocks.c:11: warning: ‘default_spin_lock_flags’ defined but not used

showed that the prototype of default_spin_lock_flags() was confused about
what type spinlocks have.

the proper type on UP is raw_spinlock_t.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/paravirt-spinlocks.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/paravirt-spinlocks.c b/arch/x86/kernel/paravirt-spinlocks.c
index 0e9f198..95777b0 100644
--- a/arch/x86/kernel/paravirt-spinlocks.c
+++ b/arch/x86/kernel/paravirt-spinlocks.c
@@ -7,7 +7,8 @@
 
 #include <asm/paravirt.h>
 
-static void default_spin_lock_flags(struct raw_spinlock *lock, unsigned long flags)
+static inline void
+default_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
 {
 	__raw_spin_lock(lock);
 }