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unr(9): allow to avoid internal locking

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Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D35014
This commit is contained in:
Konstantin Belousov 2022-04-21 01:14:37 +03:00
parent c4be460e84
commit e59b940dcb
3 changed files with 34 additions and 15 deletions
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5
share/man/man9/unr.9
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd October 4, 2017
.Dd April 21, 2022
.Dt UNR 9
.Os
.Sh NAME
@ -72,6 +72,9 @@ If
is not
.Dv NULL ,
it is used for locking when allocating and freeing units.
If the passed value is the token
.Va UNR_NO_MTX ,
then no locking is applied internally.
Otherwise, internal mutex is used.
.It Fn clear_unrhdr uh
Clear all units from the specified unit number allocator entity.

43
sys/kern/subr_unit.c
View File

@ -312,12 +312,15 @@ clean_unrhdrl(struct unrhdr *uh)
{
struct unr *up;
mtx_assert(uh->mtx, MA_OWNED);
if (uh->mtx != NULL)
mtx_assert(uh->mtx, MA_OWNED);
while ((up = TAILQ_FIRST(&uh->ppfree)) != NULL) {
TAILQ_REMOVE(&uh->ppfree, up, list);
mtx_unlock(uh->mtx);
if (uh->mtx != NULL)
mtx_unlock(uh->mtx);
Free(up);
mtx_lock(uh->mtx);
if (uh->mtx != NULL)
mtx_lock(uh->mtx);
}
}
@ -326,9 +329,11 @@ void
clean_unrhdr(struct unrhdr *uh)
{
mtx_lock(uh->mtx);
if (uh->mtx != NULL)
mtx_lock(uh->mtx);
clean_unrhdrl(uh);
mtx_unlock(uh->mtx);
if (uh->mtx != NULL)
mtx_unlock(uh->mtx);
}
void
@ -337,7 +342,9 @@ init_unrhdr(struct unrhdr *uh, int low, int high, struct mtx *mutex)
KASSERT(low >= 0 && low <= high,
("UNR: use error: new_unrhdr(%d, %d)", low, high));
if (mutex != NULL)
if (mutex == UNR_NO_MTX)
uh->mtx = NULL;
else if (mutex != NULL)
uh->mtx = mutex;
else
uh->mtx = &unitmtx;
@ -608,7 +615,8 @@ alloc_unrl(struct unrhdr *uh)
u_int x;
int y;
mtx_assert(uh->mtx, MA_OWNED);
if (uh->mtx != NULL)
mtx_assert(uh->mtx, MA_OWNED);
check_unrhdr(uh, __LINE__);
x = uh->low + uh->first;
@ -653,10 +661,12 @@ alloc_unr(struct unrhdr *uh)
{
int i;
mtx_lock(uh->mtx);
if (uh->mtx != NULL)
mtx_lock(uh->mtx);
i = alloc_unrl(uh);
clean_unrhdrl(uh);
mtx_unlock(uh->mtx);
if (uh->mtx != NULL)
mtx_unlock(uh->mtx);
return (i);
}
@ -667,7 +677,8 @@ alloc_unr_specificl(struct unrhdr *uh, u_int item, void **p1, void **p2)
struct unrb *ub;
u_int i, last, tl;
mtx_assert(uh->mtx, MA_OWNED);
if (uh->mtx != NULL)
mtx_assert(uh->mtx, MA_OWNED);
if (item < uh->low + uh->first || item > uh->high)
return (-1);
@ -773,9 +784,11 @@ alloc_unr_specific(struct unrhdr *uh, u_int item)
p1 = Malloc(sizeof(struct unr));
p2 = Malloc(sizeof(struct unr));
mtx_lock(uh->mtx);
if (uh->mtx != NULL)
mtx_lock(uh->mtx);
i = alloc_unr_specificl(uh, item, &p1, &p2);
mtx_unlock(uh->mtx);
if (uh->mtx != NULL)
mtx_unlock(uh->mtx);
if (p1 != NULL)
Free(p1);
@ -906,10 +919,12 @@ free_unr(struct unrhdr *uh, u_int item)
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "free_unr");
p1 = Malloc(sizeof(struct unr));
p2 = Malloc(sizeof(struct unr));
mtx_lock(uh->mtx);
if (uh->mtx != NULL)
mtx_lock(uh->mtx);
free_unrl(uh, item, &p1, &p2);
clean_unrhdrl(uh);
mtx_unlock(uh->mtx);
if (uh->mtx != NULL)
mtx_unlock(uh->mtx);
if (p1 != NULL)
Free(p1);
if (p2 != NULL)

1
sys/sys/systm.h
View File

@ -498,6 +498,7 @@ int root_mounted(void);
* Unit number allocation API. (kern/subr_unit.c)
*/
struct unrhdr;
#define UNR_NO_MTX ((void *)(uintptr_t)-1)
struct unrhdr *new_unrhdr(int low, int high, struct mtx *mutex);
void init_unrhdr(struct unrhdr *uh, int low, int high, struct mtx *mutex);
void delete_unrhdr(struct unrhdr *uh);