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Introduce callout_init_rm() so that callouts can be used in conjunction

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with rmlocks. This works only with non-sleepable rm because handlers run
in SWI context. While here, document the new KPI in the timeout(9)
manpage.

Requested by:	adrian, scottl
Reviewed by:	mav, remko(manpage)
This commit is contained in:
Davide Italiano 2013-08-23 14:12:39 +00:00
parent a93705b06e
commit 246fb6b232
2 changed files with 23 additions and 6 deletions
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26
share/man/man9/timeout.9
View File

@ -38,6 +38,7 @@
.Nm callout_handle_init ,
.Nm callout_init ,
.Nm callout_init_mtx ,
.Nm callout_init_rm ,
.Nm callout_init_rw ,
.Nm callout_stop ,
.Nm callout_drain ,
@ -73,6 +74,8 @@ struct callout_handle handle = CALLOUT_HANDLE_INITIALIZER(&handle);
.Fn callout_init "struct callout *c" "int mpsafe"
.Ft void
.Fn callout_init_mtx "struct callout *c" "struct mtx *mtx" "int flags"
.Fn void
.Fn callout_init_rm "struct callout *c" "struct rmlock *rm" "int flags"
.Ft void
.Fn callout_init_rw "struct callout *c" "struct rwlock *rw" "int flags"
.Ft int
@ -203,6 +206,7 @@ Thus they are protected from re-entrancy.
The functions
.Fn callout_init ,
.Fn callout_init_mtx ,
.Fn callout_init_rm ,
.Fn callout_init_rw ,
.Fn callout_stop ,
.Fn callout_drain ,
@ -252,15 +256,25 @@ after the callout function returns.
.Pp
The
.Fn callout_init_rw
function serves the need of using rwlocks in conjunction with callouts.
The function does basically the same as
.Fn callout_init_mtx
and the
.Fn callout_init_rm
fuctions serve the need of using rwlocks and rmlocks in conjunction
with callouts.
The functions do the same as
.Fn callout_init
with the possibility of specifying an extra
.Fa rw
or
.Fa rm
argument.
The usable lock classes are currently limited to mutexes and rwlocks,
because callout handlers run in softclock swi, so they cannot sleep nor
acquire sleepable locks like sx or lockmgr.
If an
.Fa rm
argument is specified, the lock should be created without passing the
.It Dv RM_SLEEPABLE
flag.
The usable lock classes are currently limited to mutexes, rwlocks and
non-sleepable rmlocks, because callout handlers run in softclock swi,
so they cannot sleep nor acquire sleepable locks like sx or lockmgr.
The following
.Fa flags
may be specified:

3
sys/sys/callout.h
View File

@ -71,6 +71,9 @@ void _callout_init_lock(struct callout *, struct lock_object *, int);
#define callout_init_mtx(c, mtx, flags) \
_callout_init_lock((c), ((mtx) != NULL) ? &(mtx)->lock_object : \
NULL, (flags))
#define callout_init_rm(c, rm, flags)
_callout_init_lock((c), ((rm != NULL) ? &(rm)->lock_object : \
NULL, (flags))
#define callout_init_rw(c, rw, flags) \
_callout_init_lock((c), ((rw) != NULL) ? &(rw)->lock_object : \
NULL, (flags))