Re: [dpdk-dev] [PATCH] ring: fix compilation error with a broken else clause

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Tue, 30 Jan 2018 14:18:46 +0530
> From: Gowrishankar <gowrishankar.m@linux.vnet.ibm.com>
> To: dev@dpdk.org
> CC: Olivier Matz <olivier.matz@6wind.com>, thomas@monjalon.net,
>  Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>
> Subject: [dpdk-dev] [PATCH] ring: fix compilation error with a broken else
>  clause
> X-Mailer: git-send-email 1.9.1
> 
> From: Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>
> 
> Calling rte_smp_wmb macro expands into a compound block, which
> would break compiling a else clause following it, if that calling
> place has been terminated already with ";", as in below code.
> This patch adds { } around this macro to allow compiling else too.
> 
> Fixes: git show c9fb3c6289 ("ring: move code in a new header file")
> 
> Signed-off-by: Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>
> ---
> 
> Error in compiling source:
> 
> In file included from /tmp/dpdk/lib/librte_ring/rte_ring.h:372:0,
>                  from /tmp/dpdk/lib/librte_ring/rte_ring.c:90:
> /tmp/dpdk/lib/librte_ring/rte_ring_generic.h: In function ‘update_tail’:
> /tmp/dpdk/lib/librte_ring/rte_ring_generic.h:75:2: error: ‘else’ without a previous ‘if’
>   else
>   ^~~~
> /tmp/dpdk/mk/internal/rte.compile-pre.mk:114: recipe for target 'rte_ring.o' failed
> 
>  lib/librte_ring/rte_ring_generic.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_ring/rte_ring_generic.h b/lib/librte_ring/rte_ring_generic.h
> index 8c3e65b..a668489 100644
> --- a/lib/librte_ring/rte_ring_generic.h
> +++ b/lib/librte_ring/rte_ring_generic.h
> @@ -70,8 +70,9 @@
>  update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t new_val,
>  		uint32_t single, uint32_t enqueue)
>  {
> -	if (enqueue)
> +	if (enqueue) {

Just wondering, Is it because of rte_smp_wmb() implementation of ppc64 is
not just correct?

We had a similar fix for arm64.
http://dpdk.org/browse/dpdk/commit/?id=59a3cae5305816b3739b4197d277f9455af53b9f


>  		rte_smp_wmb();
> +	}
>  	else
>  		rte_smp_rmb();
>  	/*
> -- 
> 1.9.1
>