[dpdk-dev] [PATCH 1/3] eal/arm64: remove the braces {} for dmb(), dsb()

[Jianbo Liu]

The 11/09/2017 11:14, Jia He wrote:
>
>
> On 11/9/2017 9:22 AM, Jia He Wrote:
> >Hi Bruce
> >
> >
> >On 11/8/2017 6:28 PM, Bruce Richardson Wrote:
> >>On Wed, Nov 08, 2017 at 06:17:10AM +0000, Jia He wrote:
> >>>for the code as follows:
> >>>if (condition)
> >>>    rte_smp_rmb();
> >>>else
> >>>    rte_smp_wmb();
> >>>Without this patch, compiler will report this error:
> >>>error: 'else' without a previous 'if'
> >>>
> >>>Signed-off-by: Jia He <hejianet at gmail.com>
> >>>Signed-off-by: jia.he at hxt-semitech.com
> >>>---
> >>>  lib/librte_eal/common/include/arch/arm/rte_atomic_64.h | 4 ++--
> >>>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>>diff --git
> >>>a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
> >>>b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
> >>>index 0b70d62..38c3393 100644
> >>>--- a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
> >>>+++ b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
> >>>@@ -43,8 +43,8 @@ extern "C" {
> >>>    #include "generic/rte_atomic.h"
> >>>  -#define dsb(opt)  { asm volatile("dsb " #opt : : : "memory"); }
> >>>-#define dmb(opt)  { asm volatile("dmb " #opt : : : "memory"); }
> >>>+#define dsb(opt) asm volatile("dsb " #opt : : : "memory");
> >>>+#define dmb(opt) asm volatile("dmb " #opt : : : "memory");
> >>Need to remove the trailing ";" I too I think.
> >>Alternatively, to keep the braces, the standard practice is to use
> >>do { ... } while(0)
> >If trailing ";" is not removed
> >the code:
> >if (condition)
> >    rte_smp_rmb();
> >else
> >    anything();
> >

Sorry, why not use two different functions as your conditions passed in
are fixed in the calling functions.

> >will be like below after precompiling:
> >if (condition)
> >    asm volatile("dsb " "ld" : : : "memory");;
> >else
> >    anything();
> >Then, the same error - error: 'else' without a previous 'if'
> >
> Ignore my words above，thanks
> sorry for the inconvenience.
> And I've sent out v4 in this mail thread. The ";" has been removed.
> If no more comments, I will send out v5 (2 patch sets for 17 and 18)
>
> --
> Cheers,
> Jia
>
>
> --
> Cheers,
> Jia
>

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