[dpdk-dev] [PATCH v4 09/20] eal/dev: implement device iteration initialization

[Wiles, Keith]

> On Mar 29, 2018, at 4:23 PM, Gaetan Rivet <gaetan.rivet at 6wind.com> wrote:
> 
> Parse a device description.
> Split this description in their relevant part for each layers.
> No dynamic allocation is performed.
> 
> Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
> ---
> lib/Makefile                            |   1 +
> lib/librte_eal/bsdapp/eal/Makefile      |   1 +
> lib/librte_eal/common/eal_common_dev.c  | 147 ++++++++++++++++++++++++++++++++
> lib/librte_eal/common/include/rte_dev.h |  23 +++++
> lib/librte_eal/linuxapp/eal/Makefile    |   1 +
> lib/librte_eal/rte_eal_version.map      |   1 +
> 6 files changed, 174 insertions(+)
> 
> diff --git a/lib/Makefile b/lib/Makefile
> index fc7a55a37..1b17526f7 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -6,6 +6,7 @@ include $(RTE_SDK)/mk/rte.vars.mk
> DIRS-y += librte_compat
> DIRS-$(CONFIG_RTE_LIBRTE_KVARGS) += librte_kvargs
> DIRS-$(CONFIG_RTE_LIBRTE_EAL) += librte_eal
> +DEPDIRS-librte_eal := librte_kvargs
> DIRS-$(CONFIG_RTE_LIBRTE_PCI) += librte_pci
> DEPDIRS-librte_pci := librte_eal
> DIRS-$(CONFIG_RTE_LIBRTE_RING) += librte_ring
> diff --git a/lib/librte_eal/bsdapp/eal/Makefile b/lib/librte_eal/bsdapp/eal/Makefile
> index 17ff1ac45..f6cea7fc2 100644
> --- a/lib/librte_eal/bsdapp/eal/Makefile
> +++ b/lib/librte_eal/bsdapp/eal/Makefile
> @@ -18,6 +18,7 @@ CFLAGS += $(WERROR_FLAGS) -O3
> LDLIBS += -lexecinfo
> LDLIBS += -lpthread
> LDLIBS += -lgcc_s
> +LDLIBS += -lrte_kvargs
> 
> EXPORT_MAP := ../../rte_eal_version.map
> 
> diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
> index cd071442f..1f6df2351 100644
> --- a/lib/librte_eal/common/eal_common_dev.c
> +++ b/lib/librte_eal/common/eal_common_dev.c
> @@ -10,9 +10,12 @@
> 
> #include <rte_compat.h>
> #include <rte_bus.h>
> +#include <rte_class.h>
> #include <rte_dev.h>
> #include <rte_devargs.h>
> #include <rte_debug.h>
> +#include <rte_errno.h>
> +#include <rte_kvargs.h>
> #include <rte_log.h>
> 
> #include "eal_private.h"
> @@ -207,3 +210,147 @@ rte_eal_hotplug_remove(const char *busname, const char *devname)
> 	rte_eal_devargs_remove(busname, devname);
> 	return ret;
> }
> +
> +static size_t
> +dev_layer_count(const char *s)
> +{
> +	size_t i = s ? 1 : 0;
> +
> +	while (s != NULL && s[0] != '\0') {
> +		i += s[0] == '/';
> +		s++;
> +	}
> +	return i;
> +}
> +
> +int __rte_experimental
> +rte_dev_iterator_init(struct rte_dev_iterator *it,
> +		      const char *devstr)
> +{
> +	struct {
> +		const char *key;
> +		const char *str;
> +		struct rte_kvargs *kvlist;
> +	} layers[] = {
> +		{ "bus=",    NULL, NULL, },
> +		{ "class=",  NULL, NULL, },
> +		{ "driver=", NULL, NULL, },
> +	};
> +	struct rte_kvargs_pair *kv = NULL;
> +	struct rte_class *cls = NULL;
> +	struct rte_bus *bus = NULL;
> +	const char *s = devstr;
> +	size_t nblayer;
> +	size_t i = 0;
> +
> +	/* Having both busstr and clsstr NULL is illegal,
> +	 * marking this iterator as invalid unless
> +	 * everything goes well.
> +	 */
> +	it->busstr = NULL;
> +	it->clsstr = NULL;
> +	/* Split each sub-lists. */
> +	nblayer = dev_layer_count(devstr);
> +	if (nblayer > RTE_DIM(layers)) {
> +		RTE_LOG(ERR, EAL, "Invalid query: too many layers (%zu)\n",
> +			nblayer);
> +		rte_errno = EINVAL;
> +		goto get_out;

This one could just return -EINVAL; instead of calling get_out.
> +	}
> +	while (s != NULL) {
> +		char *copy;
> +		char *end;
> +
> +		if (strncmp(layers[i].key, s,
> +			    strlen(layers[i].key)))
> +			goto next_layer;
> +		layers[i].str = s;
> +		copy = strdup(s);
> +		if (copy == NULL) {
> +			RTE_LOG(ERR, EAL, "OOM\n”);

Maybe spell it out in the log ‘Out of Memory’.
> +			rte_errno = ENOMEM;
> +			goto get_out;
> +		}
> +		end = strchr(copy, '/');
> +		end = end ? end : strchr(copy, '\0');
> +		end[0] = '\0';
> +		layers[i].kvlist = rte_kvargs_parse(copy, NULL);
> +		free(copy);

I am sorry this method of not adding blank lines is a bit silly and we need to rethink at least adding a few blank lines to help with grouping the code. This style will cause problems for new readers (old readers) to understand the code. This to me is a maintenance problem for the future and we need to fix this now.

Blank lines after if statements (with possible more comments) can help along with adding blank lines to group code is really the minimum amount of lines required. I have never seen someone state you have to many blanks lines in the code except two or more blank lines in a row. This is akin to having a single paragraph in a novel or letter and it makes it very hard to read. It is not hard to add some blank lines to the code for readability.

I stopped reviewing the code as it became difficult to read IMO and just causing me a headache.

This problem needs to be addressed by the TSC IMO.
> +		if (layers[i].kvlist == NULL) {
> +			RTE_LOG(ERR, EAL, "Could not parse %s\n", s);
> +			rte_errno = EINVAL;
> +			goto get_out;
> +		}
> +		s = strchr(s, '/');
> +		if (s != NULL)
> +			s++;
> +next_layer:
> +		if (i >= RTE_DIM(layers)) {
> +			RTE_LOG(ERR, EAL, "Unrecognized layer %s\n", s);
> +			rte_errno = EINVAL;
> +			goto get_out;
> +		}
> +		i++;
> +	}
> +	/* Parse each sub-list. */
> +	for (i = 0; i < RTE_DIM(layers); i++) {
> +		if (layers[i].kvlist == NULL)
> +			continue;
> +		kv = &layers[i].kvlist->pairs[0];
> +		if (strcmp(kv->key, "bus") == 0) {
> +			bus = rte_bus_find_by_name(kv->value);
> +			if (bus == NULL) {
> +				RTE_LOG(ERR, EAL, "Could not find bus \"%s\"\n",
> +					kv->value);
> +				rte_errno = EFAULT;
> +				goto get_out;
> +			}
> +		} else if (strcmp(kv->key, "class") == 0) {
> +			cls = rte_class_find_by_name(kv->value);
> +			if (cls == NULL) {
> +				RTE_LOG(ERR, EAL, "Could not find class \"%s\"\n",
> +					kv->value);
> +				rte_errno = EFAULT;
> +				goto get_out;
> +			}
> +		} else if (strcmp(kv->key, "driver") == 0) {
> +			/* Ignore */
> +			continue;
> +		}
> +	}
> +	/* The string should have at least
> +	 * one layer specified.
> +	 */
> +	if (bus == NULL && cls == NULL) {
> +		RTE_LOG(ERR, EAL,
> +			"Either bus or class must be specified.\n");
> +		rte_errno = EINVAL;
> +		goto get_out;
> +	}
> +	if (bus != NULL && bus->dev_iterate == NULL) {
> +		RTE_LOG(ERR, EAL, "Bus %s not supported\n", bus->name);
> +		rte_errno = ENOTSUP;
> +		goto get_out;
> +	}
> +	if (cls != NULL && cls->dev_iterate == NULL) {
> +		RTE_LOG(ERR, EAL, "Class %s not supported\n", cls->name);
> +		rte_errno = ENOTSUP;
> +		goto get_out;
> +	}
> +	/* Fill iterator fields. */
> +	if (bus != NULL)
> +		it->busstr = layers[0].str;
> +	if (cls != NULL)
> +		it->clsstr = layers[1].str;
> +	it->devstr = devstr;
> +	it->bus = bus;
> +	it->cls = cls;
> +	it->device = NULL;
> +	it->class_device = NULL;
> +get_out:
> +	for (i = 0; i < RTE_DIM(layers); i++) {
> +		if (layers[i].kvlist)
> +			rte_kvargs_free(layers[i].kvlist);
> +	}
> +	return -rte_errno;
> +}
> diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
> index 937ff6079..7ce13e068 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -310,6 +310,29 @@ typedef void *(*rte_dev_iterate_t)(const void *start,
> 				   const char *devstr,
> 				   const struct rte_dev_iterator *it);
> 
> +/**
> + * Initializes a device iterator.
> + *
> + * This iterator allows accessing a list of devices matching a criteria.
> + * The device matching is made among all buses and classes currently registered,
> + * filtered by the device description given as parameter.
> + *
> + * This function will not allocate any memory. It is safe to stop the
> + * iteration at any moment and let the iterator go out of context.
> + *
> + * @param it
> + *   Device iterator handle.
> + *
> + * @param str
> + *   Device description string.
> + *
> + * @return
> + *   0 on successful initialization.
> + *   <0 on error.
> + */
> +int __rte_experimental
> +rte_dev_iterator_init(struct rte_dev_iterator *it, const char *str);
> +
> #ifdef __cplusplus
> }
> #endif
> diff --git a/lib/librte_eal/linuxapp/eal/Makefile b/lib/librte_eal/linuxapp/eal/Makefile
> index a3edbbe76..87caa23a1 100644
> --- a/lib/librte_eal/linuxapp/eal/Makefile
> +++ b/lib/librte_eal/linuxapp/eal/Makefile
> @@ -27,6 +27,7 @@ LDLIBS += -lrt
> ifeq ($(CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES),y)
> LDLIBS += -lnuma
> endif
> +LDLIBS += -lrte_kvargs
> 
> # specific to linuxapp exec-env
> SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) := eal.c
> diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
> index 910cb23c9..921da3075 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -228,6 +228,7 @@ EXPERIMENTAL {
> 	rte_mp_sendmsg;
> 	rte_mp_request;
> 	rte_mp_reply;
> +	rte_dev_iterator_init;
> 	rte_service_attr_get;
> 	rte_service_attr_reset_all;
> 	rte_service_component_register;
> -- 
> 2.11.0
> 

Regards,
Keith