Re: [dpdk-dev] [PATCH v5 01/12] bus: add bus iterator to find a bus

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Jun 26, 2017 at 02:21:59AM +0200, Gaetan Rivet wrote:
> From: Jan Blunck <jblunck@infradead.org>
> 
> This helper allows to iterate over all registered buses and find one
> matching data used as parameter.
> 
> Signed-off-by: Jan Blunck <jblunck@infradead.org>
> Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
> ---
>  lib/librte_eal/bsdapp/eal/rte_eal_version.map   |  1 +
>  lib/librte_eal/common/eal_common_bus.c          | 20 ++++++++++++
>  lib/librte_eal/common/include/rte_bus.h         | 43 +++++++++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/rte_eal_version.map |  1 +
>  4 files changed, 65 insertions(+)
> 

Two minor suggestions below. Otherwise:

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

> diff --git a/lib/librte_eal/bsdapp/eal/rte_eal_version.map b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
> index 2e48a73..ed09ab2 100644
> --- a/lib/librte_eal/bsdapp/eal/rte_eal_version.map
> +++ b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
> @@ -162,6 +162,7 @@ DPDK_17.02 {
>  DPDK_17.05 {
>  	global:
>  
> +	rte_bus_find;
>  	rte_cpu_is_supported;
>  	rte_log_dump;
>  	rte_log_register;
> diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
> index 8f9baf8..4619eb2 100644
> --- a/lib/librte_eal/common/eal_common_bus.c
> +++ b/lib/librte_eal/common/eal_common_bus.c
> @@ -145,3 +145,23 @@ rte_bus_dump(FILE *f)
>  		}
>  	}
>  }
> +
> +struct rte_bus *
> +rte_bus_find(rte_bus_cmp_t cmp,
> +	     const void *data,
> +	     const struct rte_bus *start)
> +{
> +	struct rte_bus *bus = NULL;
> +	int started = start == NULL;

Please put brackets around the "start == NULL" to improve readability.
My first reading of this I assumed it was doing multiple assignment of
both start and started to NULL. To make it extra clear, prefix the
comparison with "!!".

> +
> +	TAILQ_FOREACH(bus, &rte_bus_list, next) {
> +		if (!started) {
> +			if (bus == start)
> +				started = 1;
> +			continue;
> +		}
> +		if (cmp(bus, data) == 0)
> +			break;
> +	}
> +	return bus;
> +}

I also think the name "started" is confusing, and might be better as the
slighly longer "start_found".