The branch main has been updated by jhb: URL: https://cgit.FreeBSD.org/src/commit/?id=d11f5d4762c53e6a26f005386ddfa9e67120c15c
commit d11f5d4762c53e6a26f005386ddfa9e67120c15c Author: John Baldwin <[email protected]> AuthorDate: 2022-04-21 17:40:35 +0000 Commit: John Baldwin <[email protected]> CommitDate: 2022-04-21 17:40:35 +0000 busdma_bounce: Use a simple kproc to invoke deferred requests. Rather than using a software interrupt with a single handler, just create a dedicated kernel process woken up with a simple wakeup(). Reviewed by: imp Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D34965 --- sys/kern/subr_busdma_bounce.c | 67 +++++++++++++++++++++++++------------------ 1 file changed, 39 insertions(+), 28 deletions(-) diff --git a/sys/kern/subr_busdma_bounce.c b/sys/kern/subr_busdma_bounce.c index e7a387ffd71d..2c5cc1ea83a2 100644 --- a/sys/kern/subr_busdma_bounce.c +++ b/sys/kern/subr_busdma_bounce.c @@ -45,6 +45,9 @@ * - dmat_lockarg() */ +#include <sys/kthread.h> +#include <sys/sched.h> + struct bounce_page { vm_offset_t vaddr; /* kva of bounce buffer */ bus_addr_t busaddr; /* Physical address */ @@ -87,13 +90,13 @@ static int busdma_zonecount; static STAILQ_HEAD(, bounce_zone) bounce_zone_list; static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist; static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist; -static void *busdma_ih; static MALLOC_DEFINE(M_BOUNCE, "bounce", "busdma bounce pages"); SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0, "Total bounce pages"); +static void busdma_thread(void *); static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit); @@ -152,6 +155,7 @@ static int alloc_bounce_zone(bus_dma_tag_t dmat) { struct bounce_zone *bz; + bool start_thread; /* Check to see if we already have a suitable zone */ STAILQ_FOREACH(bz, &bounce_zone_list, links) { @@ -183,6 +187,7 @@ alloc_bounce_zone(bus_dma_tag_t dmat) busdma_zonecount++; snprintf(bz->lowaddrid, sizeof(bz->lowaddrid), "%#jx", (uintmax_t)bz->lowaddr); + start_thread = STAILQ_EMPTY(&bounce_zone_list); STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links); dmat->bounce_zone = bz; @@ -232,6 +237,11 @@ alloc_bounce_zone(bus_dma_tag_t dmat) "memory domain"); #endif + if (start_thread) { + if (kproc_create(busdma_thread, NULL, NULL, 0, 0, "busdma") != + 0) + printf("failed to create busdma thread"); + } return (0); } @@ -373,7 +383,7 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage) { struct bus_dmamap *map; struct bounce_zone *bz; - bool schedule_swi; + bool schedule_thread; bz = dmat->bounce_zone; bpage->datavaddr = 0; @@ -388,7 +398,7 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage) bpage->busaddr &= ~PAGE_MASK; } - schedule_swi = false; + schedule_thread = false; mtx_lock(&bounce_lock); STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links); bz->free_bpages++; @@ -399,40 +409,41 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage) STAILQ_INSERT_TAIL(&bounce_map_callbacklist, map, links); bz->total_deferred++; - schedule_swi = true; + schedule_thread = true; } } mtx_unlock(&bounce_lock); - if (schedule_swi) - swi_sched(busdma_ih, 0); + if (schedule_thread) + wakeup(&bounce_map_callbacklist); } static void -busdma_swi(void *dummy __unused) +busdma_thread(void *dummy __unused) { + STAILQ_HEAD(, bus_dmamap) callbacklist; bus_dma_tag_t dmat; - struct bus_dmamap *map; + struct bus_dmamap *map, *nmap; - mtx_lock(&bounce_lock); - while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) { - STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links); - mtx_unlock(&bounce_lock); - dmat = map->dmat; - dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_LOCK); - bus_dmamap_load_mem(map->dmat, map, &map->mem, map->callback, - map->callback_arg, BUS_DMA_WAITOK); - dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_UNLOCK); + thread_lock(curthread); + sched_prio(curthread, PI_SWI(SWI_BUSDMA)); + thread_unlock(curthread); + for (;;) { mtx_lock(&bounce_lock); - } - mtx_unlock(&bounce_lock); -} + while (STAILQ_EMPTY(&bounce_map_callbacklist)) + mtx_sleep(&bounce_map_callbacklist, &bounce_lock, 0, + "-", 0); + STAILQ_INIT(&callbacklist); + STAILQ_CONCAT(&callbacklist, &bounce_map_callbacklist); + mtx_unlock(&bounce_lock); -static void -start_busdma_swi(void *dummy __unused) -{ - if (swi_add(NULL, "busdma", busdma_swi, NULL, SWI_BUSDMA, INTR_MPSAFE, - &busdma_ih)) - panic("died while creating busdma swi ithread"); + STAILQ_FOREACH_SAFE(map, &callbacklist, links, nmap) { + dmat = map->dmat; + dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), + BUS_DMA_LOCK); + bus_dmamap_load_mem(map->dmat, map, &map->mem, + map->callback, map->callback_arg, BUS_DMA_WAITOK); + dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), + BUS_DMA_UNLOCK); + } + } } -SYSINIT(start_busdma_swi, SI_SUB_SOFTINTR, SI_ORDER_ANY, start_busdma_swi, - NULL);
