src/udev/net/naming-scheme.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 #include <stdbool.h>
   5
   6 #include "macro.h"
   7
   8 /* So here's the deal: net_id is supposed to be an exercise in providing stable names for network devices. However, we
   9  * also want to keep updating the naming scheme used in future versions of net_id. These two goals of course are
  10  * contradictory: on one hand we want things to not change and on the other hand we want them to improve. Our way out
  11  * of this dilemma is to introduce the "naming scheme" concept: each time we improve the naming logic we define a new
  12  * flag for it. Then, we keep a list of schemes, each identified by a name associated with the flags it implements. Via
  13  * a kernel command line and environment variable we then allow the user to pick the scheme they want us to follow:
  14  * installers could "freeze" the used scheme at the moment of installation this way.
  15  *
  16  * Developers: each time you tweak the naming logic here, define a new flag below, and condition the tweak with
  17  * it. Each time we do a release we'll then add a new scheme entry and include all newly defined flags.
  18  *
  19  * Note that this is only half a solution to the problem though: not only udev/net_id gets updated all the time, the
  20  * kernel gets too. And thus a kernel that previously didn't expose some sysfs attribute we look for might eventually
  21  * do, and thus affect our naming scheme too. Thus, enforcing a naming scheme will make interfacing more stable across
  22  * OS versions, but not fully stabilize them. */
  23 typedef enum NamingSchemeFlags {
  24         /* First, the individual features */
  25         NAMING_SR_IOV_V            = 1 << 0, /* Use "v" suffix for SR-IOV, see 609948c7043a */
  26         NAMING_NPAR_ARI            = 1 << 1, /* Use NPAR "ARI", see 6bc04997b6ea */
  27         NAMING_INFINIBAND          = 1 << 2, /* Use "ib" prefix for infiniband, see 938d30aa98df */
  28         NAMING_ZERO_ACPI_INDEX     = 1 << 3, /* Use zero acpi_index field, see d81186ef4f6a */
  29         NAMING_ALLOW_RERENAMES     = 1 << 4, /* Allow re-renaming of devices, see #9006 */
  30         NAMING_NETDEVSIM           = 1 << 5, /* Generate names for netdevsim devices, see eaa9d507d855 */
  31         NAMING_LABEL_NOPREFIX      = 1 << 6, /* Don't prepend ID_NET_LABEL_ONBOARD with interface type prefix */
  32
  33         /* And now the masks that combine the features above */
  34         NAMING_V238 = 0,
  35         NAMING_V239 = NAMING_V238 | NAMING_SR_IOV_V | NAMING_NPAR_ARI,
  36         NAMING_V240 = NAMING_V239 | NAMING_INFINIBAND | NAMING_ZERO_ACPI_INDEX | NAMING_ALLOW_RERENAMES,
  37         NAMING_V243 = NAMING_V240 | NAMING_NETDEVSIM | NAMING_LABEL_NOPREFIX,
  38
  39         _NAMING_SCHEME_FLAGS_INVALID = -1,
  40 } NamingSchemeFlags;
  41
  42 typedef struct NamingScheme {
  43         const char *name;
  44         NamingSchemeFlags flags;
  45 } NamingScheme;
  46
  47 const NamingScheme* naming_scheme(void);
  48
  49 static inline bool naming_scheme_has(NamingSchemeFlags flags) {
  50         return FLAGS_SET(naming_scheme()->flags, flags);
  51 }