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intrng: track counter allocation with a bitmap

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Crucially, this allows releasing counters, and interrupt sources by
extension. Where before we were incrementing intrcnt_index with atomics,
now we protect the bitmap using the existing isrc_table_lock mutex.

Reviewed by:	mmel
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D38437
This commit is contained in:
Mitchell Horne 2023-02-14 14:02:12 -04:00
parent 82e846df5b
commit 28137bdb19
1 changed files with 40 additions and 14 deletions
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54
sys/kern/subr_intr.c
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@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bitstring.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/cpuset.h>
@ -152,7 +153,8 @@ u_long *intrcnt;
char *intrnames;
size_t sintrcnt;
size_t sintrnames;
static u_int intrcnt_index;
int nintrcnt;
static bitstr_t *intrcnt_bitmap;
static struct intr_irqsrc *intr_map_get_isrc(u_int res_id);
static void intr_map_set_isrc(u_int res_id, struct intr_irqsrc *isrc);
@ -166,7 +168,6 @@ static void intr_map_copy_map_data(u_int res_id, device_t *dev, intptr_t *xref,
static void
intr_irq_init(void *dummy __unused)
{
u_int intrcnt_count;
SLIST_INIT(&pic_list);
mtx_init(&pic_list_lock, "intr pic list", NULL, MTX_DEF);
@ -177,17 +178,21 @@ intr_irq_init(void *dummy __unused)
* - 2 counters for each I/O interrupt.
* - MAXCPU counters for each IPI counters for SMP.
*/
intrcnt_count = intr_nirq * 2;
nintrcnt = intr_nirq * 2;
#ifdef SMP
intrcnt_count += INTR_IPI_COUNT * MAXCPU;
nintrcnt += INTR_IPI_COUNT * MAXCPU;
#endif
intrcnt = mallocarray(intrcnt_count, sizeof(u_long), M_INTRNG,
intrcnt = mallocarray(nintrcnt, sizeof(u_long), M_INTRNG,
M_WAITOK | M_ZERO);
intrnames = mallocarray(intrcnt_count, INTRNAME_LEN, M_INTRNG,
intrnames = mallocarray(nintrcnt, INTRNAME_LEN, M_INTRNG,
M_WAITOK | M_ZERO);
sintrcnt = intrcnt_count * sizeof(u_long);
sintrnames = intrcnt_count * INTRNAME_LEN;
sintrcnt = nintrcnt * sizeof(u_long);
sintrnames = nintrcnt * INTRNAME_LEN;
/* Allocate the bitmap tracking counter allocations. */
intrcnt_bitmap = bit_alloc(nintrcnt, M_INTRNG, M_WAITOK | M_ZERO);
irq_sources = mallocarray(intr_nirq, sizeof(struct intr_irqsrc*),
M_INTRNG, M_WAITOK | M_ZERO);
}
@ -266,13 +271,17 @@ isrc_update_name(struct intr_irqsrc *isrc, const char *name)
static void
isrc_setup_counters(struct intr_irqsrc *isrc)
{
u_int index;
int index;
mtx_assert(&isrc_table_lock, MA_OWNED);
/*
* XXX - it does not work well with removable controllers and
* interrupt sources !!!
* Allocate two counter values, the second tracking "stray" interrupts.
*/
index = atomic_fetchadd_int(&intrcnt_index, 2);
bit_ffc_area(intrcnt_bitmap, nintrcnt, 2, &index);
if (index == -1)
panic("Failed to allocate 2 counters. Array exhausted?");
bit_nset(intrcnt_bitmap, index, index + 1);
isrc->isrc_index = index;
isrc->isrc_count = &intrcnt[index];
isrc_update_name(isrc, NULL);
@ -284,8 +293,11 @@ isrc_setup_counters(struct intr_irqsrc *isrc)
static void
isrc_release_counters(struct intr_irqsrc *isrc)
{
int idx = isrc->isrc_index;
panic("%s: not implemented", __func__);
mtx_assert(&isrc_table_lock, MA_OWNED);
bit_nclear(intrcnt_bitmap, idx, idx + 1);
}
#ifdef SMP
@ -298,11 +310,25 @@ intr_ipi_setup_counters(const char *name)
u_int index, i;
char str[INTRNAME_LEN];
index = atomic_fetchadd_int(&intrcnt_index, MAXCPU);
mtx_lock(&isrc_table_lock);
/*
* We should never have a problem finding MAXCPU contiguous counters,
* in practice. Interrupts will be allocated sequentially during boot,
* so the array should fill from low to high index. Once reserved, the
* IPI counters will never be released. Similarly, we will not need to
* allocate more IPIs once the system is running.
*/
bit_ffc_area(intrcnt_bitmap, nintrcnt, MAXCPU, &index);
if (index == -1)
panic("Failed to allocate %d counters. Array exhausted?",
MAXCPU);
bit_nset(intrcnt_bitmap, index, index + MAXCPU - 1);
for (i = 0; i < MAXCPU; i++) {
snprintf(str, INTRNAME_LEN, "cpu%d:%s", i, name);
intrcnt_setname(str, index + i);
}
mtx_unlock(&isrc_table_lock);
return (&intrcnt[index]);
}
#endif