diff options
| author | David Lamparter <equinox@diac24.net> | 2019-06-25 20:33:02 +0200 |
|---|---|---|
| committer | David Lamparter <equinox@diac24.net> | 2019-07-31 03:33:41 +0200 |
| commit | 30ef834ab3b50c09e103a82742b67ae4b0bac9f5 (patch) | |
| tree | f6ec88f064e058d78dadabe10bcb87aa58dc9157 /lib/seqlock.c | |
| parent | 2a5e62359f737b233a8b06731ce60f915a754d72 (diff) | |
lib/seqlock: add a few more comments
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
Diffstat (limited to 'lib/seqlock.c')
| -rw-r--r-- | lib/seqlock.c | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/lib/seqlock.c b/lib/seqlock.c index 6ec9bbcf5f..c05ec19db4 100644 --- a/lib/seqlock.c +++ b/lib/seqlock.c @@ -36,8 +36,14 @@ #include "seqlock.h" +/**************************************** + * OS specific synchronization wrappers * + ****************************************/ + +/* + * Linux: sys_futex() + */ #ifdef HAVE_SYNC_LINUX_FUTEX -/* Linux-specific - sys_futex() */ #include <sys/syscall.h> #include <linux/futex.h> @@ -55,8 +61,10 @@ static long sys_futex(void *addr1, int op, int val1, #define wait_poke(sqlo) \ sys_futex((int *)&sqlo->pos, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) +/* + * OpenBSD: sys_futex(), almost the same as on Linux + */ #elif defined(HAVE_SYNC_OPENBSD_FUTEX) -/* OpenBSD variant of the above. */ #include <sys/syscall.h> #include <sys/futex.h> @@ -69,8 +77,10 @@ static long sys_futex(void *addr1, int op, int val1, #define wait_poke(sqlo) \ futex((int *)&sqlo->pos, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) +/* + * FreeBSD: _umtx_op() + */ #elif defined(HAVE_SYNC_UMTX_OP) -/* FreeBSD-specific: umtx_op() */ #include <sys/umtx.h> #define wait_once(sqlo, val) \ @@ -89,9 +99,10 @@ static int wait_time(struct seqlock *sqlo, uint32_t val, #define wait_poke(sqlo) \ _umtx_op((void *)&sqlo->pos, UMTX_OP_WAKE, INT_MAX, NULL, NULL) -#else -/* generic version. used on *BSD, Solaris and OSX. +/* + * generic version. used on NetBSD, Solaris and OSX. really shitty. */ +#else #define TIME_ABS_REALTIME 1 @@ -151,6 +162,9 @@ void seqlock_wait(struct seqlock *sqlo, seqlock_val_t val) bool seqlock_timedwait(struct seqlock *sqlo, seqlock_val_t val, const struct timespec *abs_monotime_limit) { +/* + * ABS_REALTIME - used on NetBSD, Solaris and OSX + */ #if TIME_ABS_REALTIME #define time_arg1 &abs_rt #define time_arg2 NULL @@ -170,6 +184,9 @@ bool seqlock_timedwait(struct seqlock *sqlo, seqlock_val_t val, } abs_rt.tv_sec += abs_monotime_limit->tv_sec - curmono.tv_sec; +/* + * RELATIVE - used on OpenBSD (might get a patch to get absolute monotime) + */ #elif TIME_RELATIVE struct timespec reltime; @@ -183,6 +200,9 @@ bool seqlock_timedwait(struct seqlock *sqlo, seqlock_val_t val, reltime.tv_sec--; \ reltime.tv_nsec += 1000000000; \ } +/* + * FreeBSD & Linux: absolute time re. CLOCK_MONOTONIC + */ #else #define time_arg1 abs_monotime_limit #define time_arg2 NULL |