Re: [Xen-devel] [PATCH 1/2] xen/compiler: Replace opencoded __attribute__((noreturn))

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-11-25 at 10:25 +0000, Andrew Cooper wrote:
> Make a formal define for noreturn in compiler.h, and replace opencoded
> uses of __attribute__((noreturn)).
> 
> There is a stale statement in sh_skip_sync(); BUG() now contains
> unreachable(), removing the justification for having "return 0".
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> CC: Tim Deegan <tim@xxxxxxx>
> 
> ---
> 
> I have compile tested this for both arm32 and arm64
> ---
>  xen/arch/arm/early_printk.c        |    2 +-
>  xen/arch/x86/crash.c               |    2 +-
>  xen/arch/x86/mm/shadow/common.c    |    1 -
>  xen/arch/x86/shutdown.c            |    2 +-
>  xen/include/asm-arm/early_printk.h |    4 ++--
>  xen/include/xen/compiler.h         |    2 ++
>  xen/include/xen/lib.h              |    2 +-
>  xen/include/xen/sched.h            |    4 ++--
>  8 files changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/arch/arm/early_printk.c b/xen/arch/arm/early_printk.c
> index 058d044..00ec72a 100644
> --- a/xen/arch/arm/early_printk.c
> +++ b/xen/arch/arm/early_printk.c
> @@ -52,7 +52,7 @@ void __init early_printk(const char *fmt, ...)
>      va_end(args);
>  }
>  
> -void __attribute__((noreturn)) __init
> +void noreturn __init
>  early_panic(const char *fmt, ...)
>  {
>      va_list args;
> diff --git a/xen/arch/x86/crash.c b/xen/arch/x86/crash.c
> index 01fd906..836babb 100644
> --- a/xen/arch/x86/crash.c
> +++ b/xen/arch/x86/crash.c
> @@ -36,7 +36,7 @@ static unsigned int crashing_cpu;
>  static DEFINE_PER_CPU_READ_MOSTLY(bool_t, crash_save_done);
>  
>  /* This becomes the NMI handler for non-crashing CPUs, when Xen is crashing. 
> */
> -void __attribute__((noreturn)) do_nmi_crash(struct cpu_user_regs *regs)
> +void noreturn do_nmi_crash(struct cpu_user_regs *regs)
>  {
>      int cpu = smp_processor_id();
>  
> diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
> index 0bfa595..c1a416c 100644
> --- a/xen/arch/x86/mm/shadow/common.c
> +++ b/xen/arch/x86/mm/shadow/common.c
> @@ -875,7 +875,6 @@ static int sh_skip_sync(struct vcpu *v, mfn_t gl1mfn)
>      SHADOW_ERROR("gmfn %#lx was OOS but not shadowed as an l1.\n",
>                   mfn_x(gl1mfn));
>      BUG();
> -    return 0; /* BUG() is no longer __attribute__((noreturn)). */
>  }
>  
> 
> diff --git a/xen/arch/x86/shutdown.c b/xen/arch/x86/shutdown.c
> index 6eba271..6143c40 100644
> --- a/xen/arch/x86/shutdown.c
> +++ b/xen/arch/x86/shutdown.c
> @@ -85,7 +85,7 @@ static inline void kb_wait(void)
>              break;
>  }
>  
> -static void __attribute__((noreturn)) __machine_halt(void *unused)
> +static void noreturn __machine_halt(void *unused)
>  {
>      local_irq_disable();
>      for ( ; ; )
> diff --git a/xen/include/asm-arm/early_printk.h 
> b/xen/include/asm-arm/early_printk.h
> index 707bbf7..3cb8dab 100644
> --- a/xen/include/asm-arm/early_printk.h
> +++ b/xen/include/asm-arm/early_printk.h
> @@ -26,7 +26,7 @@
>  
>  void early_printk(const char *fmt, ...)
>      __attribute__((format (printf, 1, 2)));
> -void early_panic(const char *fmt, ...) __attribute__((noreturn))
> +void early_panic(const char *fmt, ...) noreturn
>      __attribute__((format (printf, 1, 2)));
>  
>  #else
> @@ -35,7 +35,7 @@ static inline  __attribute__((format (printf, 1, 2))) void
>  early_printk(const char *fmt, ...)
>  {}
>  
> -static inline void  __attribute__((noreturn))
> +static inline void noreturn
>  __attribute__((format (printf, 1, 2))) early_panic(const char *fmt, ...)
>  {while(1);}
>  
> diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
> index 7d6805c..c80398d 100644
> --- a/xen/include/xen/compiler.h
> +++ b/xen/include/xen/compiler.h
> @@ -14,6 +14,8 @@
>  #define always_inline __inline__ __attribute__ ((always_inline))
>  #define noinline      __attribute__((noinline))
>  
> +#define noreturn      __attribute__((noreturn))
> +
>  #if (!defined(__clang__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 5))
>  #define unreachable() do {} while (1)
>  #else
> diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
> index 5b258fd..814fcb4 100644
> --- a/xen/include/xen/lib.h
> +++ b/xen/include/xen/lib.h
> @@ -8,7 +8,7 @@
>  #include <xen/string.h>
>  #include <asm/bug.h>
>  
> -void __bug(char *file, int line) __attribute__((noreturn));
> +void __bug(char *file, int line) noreturn;
>  void __warn(char *file, int line);
>  
>  #define BUG_ON(p)  do { if (unlikely(p)) BUG();  } while (0)
> diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
> index cbdf377..0d2a442 100644
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -578,7 +578,7 @@ void __domain_crash(struct domain *d);
>   * Mark current domain as crashed and synchronously deschedule from the local
>   * processor. This function never returns.
>   */
> -void __domain_crash_synchronous(void) __attribute__((noreturn));
> +void __domain_crash_synchronous(void) noreturn;
>  #define domain_crash_synchronous() do {                                   \
>      printk("domain_crash_sync called from %s:%d\n", __FILE__, __LINE__);  \
>      __domain_crash_synchronous();                                         \
> @@ -589,7 +589,7 @@ void __domain_crash_synchronous(void) 
> __attribute__((noreturn));
>   * the crash occured.  If addr is 0, look up address from last extable
>   * redirection.
>   */
> -void asm_domain_crash_synchronous(unsigned long addr) 
> __attribute__((noreturn));
> +void asm_domain_crash_synchronous(unsigned long addr) noreturn;
>  
>  #define set_current_state(_s) do { current->state = (_s); } while (0)
>  void scheduler_init(void);



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