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udev: move naming-scheme bits into their own file

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This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2019-01-16 14:47:56 +01:00
parent 3907446f02
commit 35b351900f
4 changed files with 114 additions and 98 deletions
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2
src/udev/meson.build
View file

@ -41,6 +41,8 @@ libudev_core_sources = '''
net/link-config.h
net/ethtool-util.c
net/ethtool-util.h
net/naming-scheme.c
net/naming-scheme.h
'''.split()
if conf.get('HAVE_KMOD') == 1

64
src/udev/net/naming-scheme.c Normal file
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@ -0,0 +1,64 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#include "alloc-util.h"
#include "naming-scheme.h"
#include "proc-cmdline.h"
#include "string-util.h"
static const NamingScheme naming_schemes[] = {
{ "v238", NAMING_V238 },
{ "v239", NAMING_V239 },
{ "v240", NAMING_V240 },
/* … add more schemes here, as the logic to name devices is updated … */
};
static const NamingScheme* naming_scheme_from_name(const char *name) {
size_t i;
if (streq(name, "latest"))
return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
if (streq(naming_schemes[i].name, name))
return naming_schemes + i;
return NULL;
}
const NamingScheme* naming_scheme(void) {
static const NamingScheme *cache = NULL;
_cleanup_free_ char *buffer = NULL;
const char *e, *k;
if (cache)
return cache;
/* Acquire setting from the kernel command line */
(void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
/* Also acquire it from an env var */
e = getenv("NET_NAMING_SCHEME");
if (e) {
if (*e == ':') {
/* If prefixed with ':' the kernel cmdline takes precedence */
k = buffer ?: e + 1;
} else
k = e; /* Otherwise the env var takes precedence */
} else
k = buffer;
if (k) {
cache = naming_scheme_from_name(k);
if (cache) {
log_info("Using interface naming scheme '%s'.", cache->name);
return cache;
}
log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
}
cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
assert(cache);
log_info("Using default interface naming scheme '%s'.", cache->name);
return cache;
}

47
src/udev/net/naming-scheme.h Normal file
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@ -0,0 +1,47 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#include <stdbool.h>
#include "macro.h"
/* So here's the deal: net_id is supposed to be an excercise in providing stable names for network devices. However, we
* also want to keep updating the naming scheme used in future versions of net_id. These two goals of course are
* contradictory: on one hand we want things to not change and on the other hand we want them to improve. Our way out
* of this dilemma is to introduce the "naming scheme" concept: each time we improve the naming logic we define a new
* flag for it. Then, we keep a list of schemes, each identified by a name associated with the flags it implements. Via
* a kernel command line and environment variable we then allow the user to pick the scheme they want us to follow:
* installers could "freeze" the used scheme at the moment of installation this way.
*
* Developers: each time you tweak the naming logic here, define a new flag below, and condition the tweak with
* it. Each time we do a release we'll then add a new scheme entry and include all newly defined flags.
*
* Note that this is only half a solution to the problem though: not only udev/net_id gets updated all the time, the
* kernel gets too. And thus a kernel that previously didn't expose some sysfs attribute we look for might eventually
* do, and thus affect our naming scheme too. Thus, enforcing a naming scheme will make interfacing more stable across
* OS versions, but not fully stabilize them. */
typedef enum NamingSchemeFlags {
/* First, the individual features */
NAMING_SR_IOV_V = 1 << 0, /* Use "v" suffix for SR-IOV, see 609948c7043a40008b8299529c978ed8e11de8f6*/
NAMING_NPAR_ARI = 1 << 1, /* Use NPAR "ARI", see 6bc04997b6eab35d1cb9fa73889892702c27be09 */
NAMING_INFINIBAND = 1 << 2, /* Use "ib" prefix for infiniband, see 938d30aa98df887797c9e05074a562ddacdcdf5e */
NAMING_ZERO_ACPI_INDEX = 1 << 3, /* Allow zero acpi_index field, see d81186ef4f6a888a70f20a1e73a812d6acb9e22f */
/* And now the masks that combine the features above */
NAMING_V238 = 0,
NAMING_V239 = NAMING_V238 | NAMING_SR_IOV_V | NAMING_NPAR_ARI,
NAMING_V240 = NAMING_V239 | NAMING_INFINIBAND | NAMING_ZERO_ACPI_INDEX,
_NAMING_SCHEME_FLAGS_INVALID = -1,
} NamingSchemeFlags;
typedef struct NamingScheme {
const char *name;
NamingSchemeFlags flags;
} NamingScheme;
const NamingScheme* naming_scheme(void);
static inline bool naming_scheme_has(NamingSchemeFlags flags) {
return FLAGS_SET(naming_scheme()->flags, flags);
}

99
src/udev/udev-builtin-net_id.c
View file

@ -106,6 +106,7 @@
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "naming-scheme.h"
#include "parse-util.h"
#include "proc-cmdline.h"
#include "stdio-util.h"
@ -116,48 +117,6 @@
#define ONBOARD_INDEX_MAX (16*1024-1)
/* So here's the deal: net_id is supposed to be an excercise in providing stable names for network devices. However, we
* also want to keep updating the naming scheme used in future versions of net_id. These two goals of course are
* contradictory: on one hand we want things to not change and on the other hand we want them to improve. Our way out
* of this dilemma is to introduce the "naming scheme" concept: each time we improve the naming logic we define a new
* flag for it. Then, we keep a list of schemes, each identified by a name associated with the flags it implements. Via
* a kernel command line and environment variable we then allow the user to pick the scheme they want us to follow:
* installers could "freeze" the used scheme at the moment of installation this way.
*
* Developers: each time you tweak the naming logic here, define a new flag below, and condition the tweak with
* it. Each time we do a release we'll then add a new scheme entry and include all newly defined flags.
*
* Note that this is only half a solution to the problem though: not only udev/net_id gets updated all the time, the
* kernel gets too. And thus a kernel that previously didn't expose some sysfs attribute we look for might eventually
* do, and thus affect our naming scheme too. Thus, enforcing a naming scheme will make interfacing more stable across
* OS versions, but not fully stabilize them. */
typedef enum NamingSchemeFlags {
/* First, the individual features */
NAMING_SR_IOV_V = 1 << 0, /* Use "v" suffix for SR-IOV, see 609948c7043a40008b8299529c978ed8e11de8f6*/
NAMING_NPAR_ARI = 1 << 1, /* Use NPAR "ARI", see 6bc04997b6eab35d1cb9fa73889892702c27be09 */
NAMING_INFINIBAND = 1 << 2, /* Use "ib" prefix for infiniband, see 938d30aa98df887797c9e05074a562ddacdcdf5e */
NAMING_ZERO_ACPI_INDEX = 1 << 3, /* Allow zero acpi_index field, see d81186ef4f6a888a70f20a1e73a812d6acb9e22f */
/* And now the masks that combine the features above */
NAMING_V238 = 0,
NAMING_V239 = NAMING_V238|NAMING_SR_IOV_V|NAMING_NPAR_ARI,
NAMING_V240 = NAMING_V239|NAMING_INFINIBAND|NAMING_ZERO_ACPI_INDEX,
_NAMING_SCHEME_FLAGS_INVALID = -1,
} NamingSchemeFlags;
typedef struct NamingScheme {
const char *name;
NamingSchemeFlags flags;
} NamingScheme;
static const NamingScheme naming_schemes[] = {
{ "v238", NAMING_V238 },
{ "v239", NAMING_V239 },
{ "v240", NAMING_V240 },
/* … add more schemes here, as the logic to name devices is updated … */
};
enum netname_type{
NET_UNDEF,
NET_PCI,
@ -193,62 +152,6 @@ struct virtfn_info {
char suffix[IFNAMSIZ];
};
static const NamingScheme* naming_scheme_from_name(const char *name) {
size_t i;
if (streq(name, "latest"))
return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
if (streq(naming_schemes[i].name, name))
return naming_schemes + i;
return NULL;
}
static const NamingScheme* naming_scheme(void) {
static const NamingScheme *cache = NULL;
_cleanup_free_ char *buffer = NULL;
const char *e, *k;
if (cache)
return cache;
/* Acquire setting from the kernel command line */
(void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
/* Also acquire it from an env var */
e = getenv("NET_NAMING_SCHEME");
if (e) {
if (*e == ':') {
/* If prefixed with ':' the kernel cmdline takes precedence */
k = buffer ?: e + 1;
} else
k = e; /* Otherwise the env var takes precedence */
} else
k = buffer;
if (k) {
cache = naming_scheme_from_name(k);
if (cache) {
log_info("Using interface naming scheme '%s'.", cache->name);
return cache;
}
log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
}
cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
assert(cache);
log_info("Using default interface naming scheme '%s'.", cache->name);
return cache;
}
static bool naming_scheme_has(NamingSchemeFlags flags) {
return FLAGS_SET(naming_scheme()->flags, flags);
}
/* skip intermediate virtio devices */
static sd_device *skip_virtio(sd_device *dev) {
sd_device *parent;