Re: [PATCH v1 2/3] net/hyperv: implement core functionality

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 18 Dec 2017 17:46:23 +0100
Adrien Mazarguil <adrien.mazarguil@6wind.com> wrote:

>  
>  /**
> + * Destroy a hyperv context instance.
> + *
> + * @param ctx
> + *   Context to destroy.
> + */
> +static void
> +hyperv_ctx_destroy(struct hyperv_ctx *ctx)
> +{
> +	if (ctx->pipe[0] != -1)
> +		close(ctx->pipe[0]);
> +	if (ctx->pipe[1] != -1)
> +		close(ctx->pipe[1]);
> +	/* Poisoning for debugging purposes. */
> +	memset(ctx, 0x22, sizeof(*ctx));

Don't leave debug code in submitted drivers

> +	free(ctx);
> +}
> +
> +/**
> + * Iterate over system network interfaces.
> + *
> + * This function runs a given callback function for each netdevice found on
> + * the system.
> + *
> + * @param func
> + *   Callback function pointer. List traversal is aborted when this function
> + *   returns a nonzero value.
> + * @param ...
> + *   Variable parameter list passed as @p va_list to @p func.
> + *
> + * @return
> + *   0 when the entire list is traversed successfully, a negative error code
> + *   in case or failure, or the nonzero value returned by @p func when list
> + *   traversal is aborted.
> + */
> +static int
> +hyperv_foreach_iface(int (*func)(const struct if_nameindex *iface,
> +				 const struct ether_addr *eth_addr,
> +				 va_list ap), ...)
> +{
> +	struct if_nameindex *iface = if_nameindex();
> +	int s = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
> +	unsigned int i;
> +	int ret = 0;
> +
> +	if (!iface) {
> +		ret = -ENOBUFS;
> +		ERROR("cannot retrieve system network interfaces");
> +		goto error;
> +	}
> +	if (s == -1) {
> +		ret = -errno;
> +		ERROR("cannot open socket: %s", rte_strerror(errno));
> +		goto error;
> +	}
> +	for (i = 0; iface[i].if_name; ++i) {
> +		struct ifreq req;
> +		struct ether_addr eth_addr;
> +		va_list ap;
> +
> +		strncpy(req.ifr_name, iface[i].if_name, sizeof(req.ifr_name));
> +		if (ioctl(s, SIOCGIFHWADDR, &req) == -1) {
> +			WARN("cannot retrieve information about interface"
> +			     " \"%s\": %s",
> +			     req.ifr_name, rte_strerror(errno));
> +			continue;
> +		}
> +		memcpy(eth_addr.addr_bytes, req.ifr_hwaddr.sa_data,
> +		       RTE_DIM(eth_addr.addr_bytes));
> +		va_start(ap, func);
> +		ret = func(&iface[i], &eth_addr, ap);
> +		va_end(ap);
> +		if (ret)
> +			break;
> +	}
> +error:
> +	if (s != -1)
> +		close(s);
> +	if (iface)
> +		if_freenameindex(iface);
> +	return ret;
> +}
> +
> +/**
> + * Determine if a network interface is NetVSC.
> + *
> + * @param[in] iface
> + *   Pointer to netdevice description structure (name and index).
> + *
> + * @return
> + *   A nonzero value when interface is detected as NetVSC. In case of error,
> + *   rte_errno is updated and 0 returned.
> + */
> +static int
> +hyperv_iface_is_netvsc(const struct if_nameindex *iface)
> +{
> +	static const char temp[] = "/sys/class/net/%s/device/class_id";
> +	char path[snprintf(NULL, 0, temp, iface->if_name) + 1];

Doing this snprintf is gross. Either use PATH_MAX or asprintf

> +	FILE *f;
> +	int ret;
> +	int len = 0;
> +
> +	snprintf(path, sizeof(path), temp, iface->if_name);
> +	f = fopen(path, "r");
> +	if (!f) {
> +		rte_errno = errno;
> +		return 0;
> +	}
> +	ret = fscanf(f, NETVSC_CLASS_ID "%n", &len);
> +	if (ret == EOF)
> +		rte_errno = errno;
> +	ret = len == (int)strlen(NETVSC_CLASS_ID);
> +	fclose(f);
> +	return ret;
> +}
> +
> +/**
> + * Retrieve the last component of a path.
> + *
> + * This is a simplified basename() that does not modify its input buffer to
> + * handle trailing backslashes.
> + *
> + * @param[in] path
> + *    Path to retrieve the last component from.
> + *
> + * @return
> + *    Pointer to the last component.
> + */
> +static const char *
> +hyperv_basename(const char *path)
> +{
> +	const char *tmp = path;
> +
> +	while (*tmp)
> +		if (*(tmp++) == '/')

Too may ()

> +			path = tmp;
> +	return path;
> +}
> +
> +/**
> + * Retrieve network interface data from sysfs symbolic link.
> + *
> + * @param[out] buf
> + *   Output data buffer.
> + * @param size
> + *   Output buffer size.
> + * @param[in] if_name
> + *   Netdevice name.
> + * @param[in] relpath
> + *   Symbolic link path relative to netdevice sysfs entry.
> + *
> + * @return
> + *   0 on success, a negative error code otherwise.
> + */
> +static int
> +hyperv_sysfs_readlink(char *buf, size_t size, const char *if_name,
> +		      const char *relpath)
> +{
> +	int ret;
> +
> +	ret = snprintf(buf, size, "/sys/class/net/%s/%s", if_name, relpath);
> +	if (ret == -1 || (size_t)ret >= size - 1)
> +		return -ENOBUFS;
> +	ret = readlink(buf, buf, size);
> +	if (ret == -1)
> +		return -errno;
> +	if ((size_t)ret >= size - 1)
> +		return -ENOBUFS;
> +	buf[ret] = '\0';
> +	return 0;
> +}
> +
> +/**
> + * Probe a network interface to associate with hyperv context.
> + *
> + * This function determines if the network device matches the properties of
> + * the NetVSC interface associated with the hyperv context and communicates
> + * its bus address to the fail-safe PMD instance if so.
> + *
> + * It is normally used with hyperv_foreach_iface().
> + *
> + * @param[in] iface
> + *   Pointer to netdevice description structure (name and index).
> + * @param[in] eth_addr
> + *   MAC address associated with @p iface.
> + * @param ap
> + *   Variable arguments list comprising:
> + *
> + *   - struct hyperv_ctx *ctx:
> + *     Context to associate network interface with.
> + *
> + * @return
> + *   A nonzero value when interface matches, 0 otherwise or in case of
> + *   error.
> + */
> +static int
> +hyperv_device_probe(const struct if_nameindex *iface,
> +		    const struct ether_addr *eth_addr,
> +		    va_list ap)
> +{
> +	struct hyperv_ctx *ctx = va_arg(ap, struct hyperv_ctx *);
> +	char buf[RTE_MAX(sizeof(ctx->yield), 256u)];
> +	const char *addr;
> +	size_t len;
> +	int ret;
> +
> +	/* Skip non-matching or unwanted NetVSC interfaces. */
> +	if (ctx->if_index == iface->if_index) {
> +		if (!strcmp(ctx->if_name, iface->if_name))
> +			return 0;
> +		DEBUG("NetVSC interface \"%s\" (index %u) renamed \"%s\"",
> +		      ctx->if_name, ctx->if_index, iface->if_name);
> +		strncpy(ctx->if_name, iface->if_name, sizeof(ctx->if_name));
> +		return 0;
> +	}
> +	if (hyperv_iface_is_netvsc(iface))
> +		return 0;
> +	if (!is_same_ether_addr(eth_addr, &ctx->if_addr))
> +		return 0;
> +	/* Look for associated PCI device. */
> +	ret = hyperv_sysfs_readlink(buf, sizeof(buf), iface->if_name,
> +				    "device/subsystem");
> +	if (ret)
> +		return 0;
> +	if (strcmp(hyperv_basename(buf), "pci"))
> +		return 0;
> +	ret = hyperv_sysfs_readlink(buf, sizeof(buf), iface->if_name,
> +				    "device");
> +	if (ret)
> +		return 0;
> +	addr = hyperv_basename(buf);
> +	len = strlen(addr);
> +	if (!len)
> +		return 0;
> +	/* Send PCI device argument to fail-safe PMD instance if updated. */
> +	if (!strcmp(addr, ctx->yield))
> +		return 1;
> +	DEBUG("associating PCI device \"%s\" with NetVSC interface \"%s\""
> +	      " (index %u)",
> +	      addr, ctx->if_name, ctx->if_index);
> +	memmove(buf, addr, len + 1);
> +	addr = buf;
> +	buf[len] = '\n';
> +	ret = write(ctx->pipe[1], addr, len + 1);
> +	buf[len] = '\0';
> +	if (ret == -1) {
> +		if (errno == EINTR || errno == EAGAIN)
> +			return 1;
> +		WARN("cannot associate PCI device name \"%s\" with interface"
> +		     " \"%s\": %s",
> +		     addr, ctx->if_name, rte_strerror(errno));
> +		return 1;
> +	}
> +	if ((size_t)ret != len + 1) {
> +		/*
> +		 * Attempt to override previous partial write, no need to
> +		 * recover if that fails.
> +		 */
> +		ret = write(ctx->pipe[1], "\n", 1);
> +		(void)ret;
> +		return 1;
> +	}
> +	fsync(ctx->pipe[1]);
> +	memcpy(ctx->yield, addr, len + 1);
> +	return 1;
> +}
> +
> +/**
> + * Alarm callback that regularly probes system network interfaces.
> + *
> + * This callback runs at a frequency determined by HYPERV_PROBE_MS as long
> + * as an hyperv context instance exists.
> + *
> + * @param arg
> + *   Ignored.
> + */
> +static void
> +hyperv_alarm(void *arg)
> +{
> +	struct hyperv_ctx *ctx;
> +	int ret;
> +
> +	(void)arg;

I assume you are trying to suppress unused warnings.
The DPDK method of doing this __rte_unused

> +	LIST_FOREACH(ctx, &hyperv_ctx_list, entry) {
> +		ret = hyperv_foreach_iface(hyperv_device_probe, ctx);
> +		if (ret)
> +			break;
> +	}
> +	if (!hyperv_ctx_count)
> +		return;
> +	ret = rte_eal_alarm_set(HYPERV_PROBE_MS * 1000, hyperv_alarm, NULL);
> +	if (ret < 0) {
> +		ERROR("unable to reschedule alarm callback: %s",
> +		      rte_strerror(-ret));
> +	}
> +}
> +
> +/**
> + * Probe a NetVSC interface to generate a hyperv context from.
> + *
> + * This function instantiates hyperv contexts either for all NetVSC devices
> + * found on the system or only a subset provided as device arguments.
> + *
> + * It is normally used with hyperv_foreach_iface().
> + *
> + * @param[in] iface
> + *   Pointer to netdevice description structure (name and index).
> + * @param[in] eth_addr
> + *   MAC address associated with @p iface.
> + * @param ap
> + *   Variable arguments list comprising:
> + *
> + *   - const char *name:
> + *     Name associated with current driver instance.
> + *
> + *   - struct rte_kvargs *kvargs:
> + *     Device arguments provided to current driver instance.
> + *
> + *   - unsigned int specified:
> + *     Number of specific netdevices provided as device arguments.
> + *
> + *   - unsigned int *matched:
> + *     The number of specified netdevices matched by this function.
> + *
> + * @return
> + *   A nonzero value when interface matches, 0 otherwise or in case of
> + *   error.
> + */
> +static int
> +hyperv_netvsc_probe(const struct if_nameindex *iface,
> +		    const struct ether_addr *eth_addr,
> +		    va_list ap)
> +{
> +	const char *name = va_arg(ap, const char *);
> +	struct rte_kvargs *kvargs = va_arg(ap, struct rte_kvargs *);
> +	unsigned int specified = va_arg(ap, unsigned int);
> +	unsigned int *matched = va_arg(ap, unsigned int *);
> +	unsigned int i;
> +	struct hyperv_ctx *ctx;
> +	uint16_t port_id;
> +	int ret;
> +
> +	/* Probe all interfaces when none are specified. */
> +	if (specified) {
> +		for (i = 0; i != kvargs->count; ++i) {
> +			const struct rte_kvargs_pair *pair = &kvargs->pairs[i];
> +
> +			if (!strcmp(pair->key, HYPERV_ARG_IFACE)) {
> +				if (!strcmp(pair->value, iface->if_name))
> +					break;
> +			} else if (!strcmp(pair->key, HYPERV_ARG_MAC)) {
> +				struct ether_addr tmp;
> +
> +				if (ether_addr_from_str(&tmp, pair->value)) {
> +					ERROR("invalid MAC address format"
> +					      " \"%s\"",
> +					      pair->value);
> +					return -EINVAL;
> +				}
> +				if (!is_same_ether_addr(eth_addr, &tmp))
> +					break;
> +			}
> +		}
> +		if (i == kvargs->count)
> +			return 0;
> +		++(*matched);
> +	}
> +	/* Weed out interfaces already handled. */
> +	LIST_FOREACH(ctx, &hyperv_ctx_list, entry)
> +		if (ctx->if_index == iface->if_index)
> +			break;
> +	if (ctx) {
> +		if (!specified)
> +			return 0;
> +		WARN("interface \"%s\" (index %u) is already handled, skipping",
> +		     iface->if_name, iface->if_index);
> +		return 0;
> +	}
> +	if (!hyperv_iface_is_netvsc(iface)) {
> +		if (!specified)
> +			return 0;
> +		WARN("interface \"%s\" (index %u) is not NetVSC, skipping",
> +		     iface->if_name, iface->if_index);
> +		return 0;
> +	}
> +	/* Create interface context. */
> +	ctx = calloc(1, sizeof(*ctx));
> +	if (!ctx) {
> +		ret = -errno;
> +		ERROR("cannot allocate context for interface \"%s\": %s",
> +		      iface->if_name, rte_strerror(errno));
> +		goto error;
> +	}
> +	ctx->id = hyperv_ctx_count;
> +	strncpy(ctx->if_name, iface->if_name, sizeof(ctx->if_name));
> +	ctx->if_index = iface->if_index;
> +	ctx->if_addr = *eth_addr;
> +	ctx->pipe[0] = -1;
> +	ctx->pipe[1] = -1;
> +	ctx->yield[0] = '\0';
> +	if (pipe(ctx->pipe) == -1) {
> +		ret = -errno;
> +		ERROR("cannot allocate control pipe for interface \"%s\": %s",
> +		      ctx->if_name, rte_strerror(errno));
> +		goto error;
> +	}
> +	for (i = 0; i != RTE_DIM(ctx->pipe); ++i) {
> +		int flf = fcntl(ctx->pipe[i], F_GETFL);
> +		int fdf = fcntl(ctx->pipe[i], F_GETFD);
> +
> +		if (flf != -1 &&
> +		    fcntl(ctx->pipe[i], F_SETFL, flf | O_NONBLOCK) != -1 &&
> +		    fdf != -1 &&
> +		    fcntl(ctx->pipe[i], F_SETFD,
> +			  i ? fdf | FD_CLOEXEC : fdf & ~FD_CLOEXEC) != -1)
> +			continue;
> +		ret = -errno;
> +		ERROR("cannot toggle non-blocking or close-on-exec flags on"
> +		      " control file descriptor #%u (%d): %s",
> +		      i, ctx->pipe[i], rte_strerror(errno));
> +		goto error;
> +	}
> +	/* Generate virtual device name and arguments. */
> +	i = 0;
> +	ret = snprintf(ctx->name, sizeof(ctx->name), "%s_id%u",
> +		       name, ctx->id);
> +	if (ret == -1 || (size_t)ret >= sizeof(ctx->name) - 1)
> +		++i;
> +	ret = snprintf(ctx->devname, sizeof(ctx->devname), "net_failsafe_%s",
> +		       ctx->name);
> +	if (ret == -1 || (size_t)ret >= sizeof(ctx->devname) - 1)
> +		++i;
> +	/*
> +	 * Note: bash replaces the default sh interpreter used by popen()
> +	 * because as seen with dash, POSIX-compliant shells do not
> +	 * necessarily support redirections with file descriptor numbers
> +	 * above 9.
> +	 */
> +	ret = snprintf(ctx->devargs, sizeof(ctx->devargs),
> +		       "exec(exec bash -c "
> +		       "'while read -r tmp <&%u 2> /dev/null;"
> +		       " do dev=$tmp; done;"
> +		       " echo $dev"
> +		       "'),dev(net_tap_%s,remote=%s)",
> +		       ctx->pipe[0], ctx->name, ctx->if_name);


Write real code. Shelling out to bash is messy, error prone and potential
security issue.

> +	if (ret == -1 || (size_t)ret >= sizeof(ctx->devargs) - 1)
> +		++i;



> +	if (i) {
> +		ret = -ENOBUFS;
> +		ERROR("generated virtual device name or argument list too long"
> +		      " for interface \"%s\"", ctx->if_name);
> +		goto error;
> +	}
> +	/*
> +	 * Remove any competing rte_eth_dev entries sharing the same MAC
> +	 * address, fail-safe instances created by this PMD will handle them
> +	 * as sub-devices later.
> +	 */
> +	RTE_ETH_FOREACH_DEV(port_id) {
> +		struct rte_device *dev = rte_eth_devices[port_id].device;
> +		struct rte_bus *bus = rte_bus_find_by_device(dev);
> +		struct ether_addr tmp;
> +
> +		rte_eth_macaddr_get(port_id, &tmp);
> +		if (!is_same_ether_addr(eth_addr, &tmp))
> +			continue;
> +		WARN("removing device \"%s\" with identical MAC address to"
> +		     " re-create it as a fail-safe sub-device",
> +		     dev->name);
> +		if (!bus)
> +			ret = -EINVAL;
> +		else
> +			ret = rte_eal_hotplug_remove(bus->name, dev->name);
> +		if (ret < 0) {
> +			ERROR("unable to remove device \"%s\": %s",
> +			      dev->name, rte_strerror(-ret));
> +			goto error;
> +		}
> +	}
> +	/* Request virtual device generation. */
> +	DEBUG("generating virtual device \"%s\" with arguments \"%s\"",
> +	      ctx->devname, ctx->devargs);
> +	ret = rte_eal_hotplug_add("vdev", ctx->devname, ctx->devargs);
> +	if (ret)
> +		goto error;
> +	LIST_INSERT_HEAD(&hyperv_ctx_list, ctx, entry);
> +	++hyperv_ctx_count;
> +	DEBUG("added NetVSC interface \"%s\" to context list", ctx->if_name);
> +	return 0;
> +error:
> +	if (ctx)
> +		hyperv_ctx_destroy(ctx);
> +	return ret;
> +}
> +
> +/**
>   * Probe NetVSC interfaces.
>   *
> + * This function probes system netdevices according to the specified device
> + * arguments and starts a periodic alarm callback to notify the resulting
> + * fail-safe PMD instances of their sub-devices whereabouts.
> + *
>   * @param dev
>   *   Virtual device context for PMD instance.
>   *
> @@ -92,12 +706,38 @@ hyperv_vdev_probe(struct rte_vdev_device *dev)
>  	const char *args = rte_vdev_device_args(dev);
>  	struct rte_kvargs *kvargs = rte_kvargs_parse(args ? args : "",
>  						     hyperv_arg);
> +	unsigned int specified = 0;
> +	unsigned int matched = 0;
> +	unsigned int i;
> +	int ret;
>  
>  	DEBUG("invoked as \"%s\", using arguments \"%s\"", name, args);
>  	if (!kvargs) {
>  		ERROR("cannot parse arguments list");
>  		goto error;
>  	}
> +	for (i = 0; i != kvargs->count; ++i) {
> +		const struct rte_kvargs_pair *pair = &kvargs->pairs[i];
> +
> +		if (!strcmp(pair->key, HYPERV_ARG_IFACE) ||
> +		    !strcmp(pair->key, HYPERV_ARG_MAC))
> +			++specified;
> +	}
> +	rte_eal_alarm_cancel(hyperv_alarm, NULL);
> +	/* Gather interfaces. */
> +	ret = hyperv_foreach_iface(hyperv_netvsc_probe, name, kvargs,
> +				   specified, &matched);
> +	if (ret < 0)
> +		goto error;
> +	if (matched < specified)
> +		WARN("some of the specified parameters did not match valid"
> +		     " network interfaces");
> +	ret = rte_eal_alarm_set(HYPERV_PROBE_MS * 1000, hyperv_alarm, NULL);
> +	if (ret < 0) {
> +		ERROR("unable to schedule alarm callback: %s",
> +		      rte_strerror(-ret));
> +		goto error;
> +	}
>  error:
>  	if (kvargs)
>  		rte_kvargs_free(kvargs);
> @@ -108,6 +748,9 @@ hyperv_vdev_probe(struct rte_vdev_device *dev)
>  /**
>   * Remove PMD instance.
>   *
> + * The alarm callback and underlying hyperv context instances are only
> + * destroyed after the last PMD instance is removed.
> + *
>   * @param dev
>   *   Virtual device context for PMD instance.
>   *
> @@ -118,7 +761,16 @@ static int
>  hyperv_vdev_remove(struct rte_vdev_device *dev)
>  {
>  	(void)dev;
> -	--hyperv_ctx_inst;
> +	if (--hyperv_ctx_inst)
> +		return 0;
> +	rte_eal_alarm_cancel(hyperv_alarm, NULL);
> +	while (!LIST_EMPTY(&hyperv_ctx_list)) {
> +		struct hyperv_ctx *ctx = LIST_FIRST(&hyperv_ctx_list);
> +
> +		LIST_REMOVE(ctx, entry);
> +		--hyperv_ctx_count;
> +		hyperv_ctx_destroy(ctx);
> +	}
>  	return 0;
>  }
>