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

[gowrishankar muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>]

On Tuesday 30 January 2018 02:26 PM, Jerin Jacob wrote:
> -----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
Thanks Jerin. Yes. Similar fix also works. I did not want to touch 
include/ at this time, as it is called at various places in source.
As same problem is seen in arm64, I think it is ok to go with your 
change. If so, I can send version 2 patch with similar change as you showed.

Thanks,
Gowrishankar

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