Subject: Re: [PATCH] powerpc: don't re-issue spinlock typedef that breaks older gcc

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 28 Jan 2014 22:58:54 +0530

Paul Gortmaker <[email-masked]> writes:

> Commit b3084f4db3aeb991c507ca774337c7e7893ed04f ("powerpc/thp: Fix
> crash on mremap") added a "typedef struct spinlock spinlock_t;"
> which on gcc 4.5.2 (and possibly other versions) causes many of:
>
> include/linux/spinlock_types.h:76:3: error: redefinition of typedef 'spinlock_t'
> arch/powerpc/include/asm/pgtable-ppc64.h:563:25: note: previous declaration of 'spinlock_t' was here
> In file included from include/linux/mutex.h:15:0,
>                  from include/linux/notifier.h:13,
>                  from include/linux/pm_qos.h:8,
>                  from include/linux/netdevice.h:28,
>                  from drivers/net/wireless/ath/wil6210/wil6210.h:20,
>                  from drivers/net/wireless/ath/wil6210/debug.c:17:
>
> It appears that somewhere between gcc 4.5.2 and 4.6.3 this
> redefinition restriction was lifted.  Using the proper header
> from within !ASSEMBLY seems to fix it up in an acceptable way.
>
> Cc: Aneesh Kumar K.V <[email-masked]>
> Cc: Kirill A. Shutemov <[email-masked]>
> Cc: Benjamin Herrenschmidt <[email-masked]>
> Signed-off-by: Paul Gortmaker <[email-masked]>
> ---
>

http://mid.gmane.org/[email-masked]

This was posted earlier.

> [ Note that b3084f4db3 isn't mainline yet, it is currently in
>   benh/powerpc.git #merge -- but is headed there soon via:
>              https://lkml.org/lkml/2014/1/27/599           ]
>
>  arch/powerpc/include/asm/pgtable-ppc64.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
> index d27960c89a71..3b638411646a 100644
> --- a/arch/powerpc/include/asm/pgtable-ppc64.h
> +++ b/arch/powerpc/include/asm/pgtable-ppc64.h
> @@ -111,6 +111,8 @@
>
>  #ifndef __ASSEMBLY__
>
> +#include <linux/spinlock_types.h>
> +
>  /*
>   * This is the default implementation of various PTE accessors, it's
>   * used in all cases except Book3S with 64K pages where we have a
> @@ -560,7 +562,6 @@ extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
>  			    pmd_t *pmdp);
>
>  #define pmd_move_must_withdraw pmd_move_must_withdraw
> -typedef struct spinlock spinlock_t;
>  static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
>  					 spinlock_t *old_pmd_ptl)
>  {
> -- 
> 1.8.5.2