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
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@ -45,6 +45,9 @@
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* - dmat_lockarg()
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*/
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#include <sys/kthread.h>
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#include <sys/sched.h>
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struct bounce_page {
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vm_offset_t vaddr; /* kva of bounce buffer */
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bus_addr_t busaddr; /* Physical address */
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@ -87,13 +90,13 @@ static int busdma_zonecount;
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static STAILQ_HEAD(, bounce_zone) bounce_zone_list;
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static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
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static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
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static void *busdma_ih;
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static MALLOC_DEFINE(M_BOUNCE, "bounce", "busdma bounce pages");
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SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
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"Total bounce pages");
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static void busdma_thread(void *);
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static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
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int commit);
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@ -152,6 +155,7 @@ static int
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alloc_bounce_zone(bus_dma_tag_t dmat)
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{
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struct bounce_zone *bz;
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bool start_thread;
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/* Check to see if we already have a suitable zone */
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STAILQ_FOREACH(bz, &bounce_zone_list, links) {
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@ -183,6 +187,7 @@ alloc_bounce_zone(bus_dma_tag_t dmat)
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busdma_zonecount++;
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snprintf(bz->lowaddrid, sizeof(bz->lowaddrid), "%#jx",
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(uintmax_t)bz->lowaddr);
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start_thread = STAILQ_EMPTY(&bounce_zone_list);
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STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
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dmat->bounce_zone = bz;
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@ -232,6 +237,11 @@ alloc_bounce_zone(bus_dma_tag_t dmat)
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"memory domain");
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#endif
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if (start_thread) {
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if (kproc_create(busdma_thread, NULL, NULL, 0, 0, "busdma") !=
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0)
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printf("failed to create busdma thread");
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}
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return (0);
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}
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@ -373,7 +383,7 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
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{
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struct bus_dmamap *map;
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struct bounce_zone *bz;
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bool schedule_swi;
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bool schedule_thread;
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bz = dmat->bounce_zone;
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bpage->datavaddr = 0;
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@ -388,7 +398,7 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
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bpage->busaddr &= ~PAGE_MASK;
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}
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schedule_swi = false;
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schedule_thread = false;
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mtx_lock(&bounce_lock);
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STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
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bz->free_bpages++;
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@ -399,40 +409,41 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
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STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
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map, links);
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bz->total_deferred++;
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schedule_swi = true;
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schedule_thread = true;
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}
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}
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mtx_unlock(&bounce_lock);
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if (schedule_swi)
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swi_sched(busdma_ih, 0);
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if (schedule_thread)
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wakeup(&bounce_map_callbacklist);
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}
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static void
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busdma_swi(void *dummy __unused)
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busdma_thread(void *dummy __unused)
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{
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STAILQ_HEAD(, bus_dmamap) callbacklist;
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bus_dma_tag_t dmat;
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struct bus_dmamap *map;
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struct bus_dmamap *map, *nmap;
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mtx_lock(&bounce_lock);
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while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
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STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
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mtx_unlock(&bounce_lock);
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dmat = map->dmat;
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dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_LOCK);
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bus_dmamap_load_mem(map->dmat, map, &map->mem, map->callback,
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map->callback_arg, BUS_DMA_WAITOK);
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dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_UNLOCK);
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thread_lock(curthread);
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sched_prio(curthread, PI_SWI(SWI_BUSDMA));
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thread_unlock(curthread);
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for (;;) {
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mtx_lock(&bounce_lock);
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}
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mtx_unlock(&bounce_lock);
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}
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while (STAILQ_EMPTY(&bounce_map_callbacklist))
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mtx_sleep(&bounce_map_callbacklist, &bounce_lock, 0,
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"-", 0);
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STAILQ_INIT(&callbacklist);
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STAILQ_CONCAT(&callbacklist, &bounce_map_callbacklist);
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mtx_unlock(&bounce_lock);
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static void
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start_busdma_swi(void *dummy __unused)
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{
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if (swi_add(NULL, "busdma", busdma_swi, NULL, SWI_BUSDMA, INTR_MPSAFE,
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&busdma_ih))
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panic("died while creating busdma swi ithread");
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STAILQ_FOREACH_SAFE(map, &callbacklist, links, nmap) {
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dmat = map->dmat;
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dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat),
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BUS_DMA_LOCK);
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bus_dmamap_load_mem(map->dmat, map, &map->mem,
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map->callback, map->callback_arg, BUS_DMA_WAITOK);
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dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat),
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BUS_DMA_UNLOCK);
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}
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}
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}
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SYSINIT(start_busdma_swi, SI_SUB_SOFTINTR, SI_ORDER_ANY, start_busdma_swi,
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NULL);
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