projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| a410a0cf GN |
1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| 2 | /* | |
| 3 | * inet_dscp.h: helpers for handling differentiated services codepoints (DSCP) | |
| 4 | * | |
| 5 | * DSCP is defined in RFC 2474: | |
| 6 | * | |
| 7 | * 0 1 2 3 4 5 6 7 | |
| 8 | * +---+---+---+---+---+---+---+---+ | |
| 9 | * | DSCP | CU | | |
| 10 | * +---+---+---+---+---+---+---+---+ | |
| 11 | * | |
| 12 | * DSCP: differentiated services codepoint | |
| 13 | * CU: currently unused | |
| 14 | * | |
| 15 | * The whole DSCP + CU bits form the DS field. | |
| 16 | * The DS field is also commonly called TOS or Traffic Class (for IPv6). | |
| 17 | * | |
| 18 | * Note: the CU bits are now used for Explicit Congestion Notification | |
| 19 | * (RFC 3168). | |
| 20 | */ | |
| 21 | ||
| 22 | #ifndef _INET_DSCP_H | |
| 23 | #define _INET_DSCP_H | |
| 24 | ||
| 25 | #include <linux/types.h> | |
| 26 | ||
| 27 | /* Special type for storing DSCP values. | |
| 28 | * | |
| 29 | * A dscp_t variable stores a DS field with the CU (ECN) bits cleared. | |
| 30 | * Using dscp_t allows to strictly separate DSCP and ECN bits, thus avoiding | |
| 31 | * bugs where ECN bits are erroneously taken into account during FIB lookups | |
| 32 | * or policy routing. | |
| 33 | * | |
| 34 | * Note: to get the real DSCP value contained in a dscp_t variable one would | |
| 35 | * have to do a bit shift after calling inet_dscp_to_dsfield(). We could have | |
| 36 | * a helper for that, but there's currently no users. | |
| 37 | */ | |
| 38 | typedef u8 __bitwise dscp_t; | |
| 39 | ||
| 40 | #define INET_DSCP_MASK 0xfc | |
| 41 | ||
| 42 | static inline dscp_t inet_dsfield_to_dscp(__u8 dsfield) | |
| 43 | { | |
| 44 | return (__force dscp_t)(dsfield & INET_DSCP_MASK); | |
| 45 | } | |
| 46 | ||
| 47 | static inline __u8 inet_dscp_to_dsfield(dscp_t dscp) | |
| 48 | { | |
| 49 | return (__force __u8)dscp; | |
| 50 | } | |
| 51 | ||
| 52 | static inline bool inet_validate_dscp(__u8 val) | |
| 53 | { | |
| 54 | return !(val & ~INET_DSCP_MASK); | |
| 55 | } | |
| 56 | ||
| 57 | #endif /* _INET_DSCP_H */ |