d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

busdma_iommu: Fine-grained locking for the dmamap's map list

Browse Source 
Introduce fine-grained locking on the dmamap's list of map entries,
replacing the use of the domain lock.  This is not the most significant
source of lock contention, but it is the easiest to address.

Reviewed by:	kib
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D35557
This commit is contained in:
Alan Cox 2022-06-22 16:51:47 -05:00
parent c11e64ce51
commit eeb46578c2
2 changed files with 34 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
sys/dev/iommu/busdma_iommu.c
View File

@ -458,6 +458,7 @@ iommu_bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
return (ENOMEM);
}
}
IOMMU_DMAMAP_INIT(map);
TAILQ_INIT(&map->map_entries);
map->tag = tag;
map->locked = true;
@ -473,18 +474,16 @@ iommu_bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map1)
{
struct bus_dma_tag_iommu *tag;
struct bus_dmamap_iommu *map;
struct iommu_domain *domain;
tag = (struct bus_dma_tag_iommu *)dmat;
map = (struct bus_dmamap_iommu *)map1;
if (map != NULL) {
domain = tag->ctx->domain;
IOMMU_DOMAIN_LOCK(domain);
IOMMU_DMAMAP_LOCK(map);
if (!TAILQ_EMPTY(&map->map_entries)) {
IOMMU_DOMAIN_UNLOCK(domain);
IOMMU_DMAMAP_UNLOCK(map);
return (EBUSY);
}
IOMMU_DOMAIN_UNLOCK(domain);
IOMMU_DMAMAP_DESTROY(map);
free(map, M_IOMMU_DMAMAP);
}
tag->map_count--;
@ -625,10 +624,11 @@ iommu_bus_dmamap_load_something1(struct bus_dma_tag_iommu *tag,
(uintmax_t)entry->start, (uintmax_t)entry->end,
(uintmax_t)buflen1, (uintmax_t)tag->common.maxsegsz));
IOMMU_DOMAIN_LOCK(domain);
KASSERT((entry->flags & IOMMU_MAP_ENTRY_MAP) != 0,
("entry %p missing IOMMU_MAP_ENTRY_MAP", entry));
IOMMU_DMAMAP_LOCK(map);
TAILQ_INSERT_TAIL(&map->map_entries, entry, dmamap_link);
entry->flags |= IOMMU_MAP_ENTRY_MAP;
IOMMU_DOMAIN_UNLOCK(domain);
IOMMU_DMAMAP_UNLOCK(map);
TAILQ_INSERT_TAIL(unroll_list, entry, unroll_link);
segs[seg].ds_addr = entry->start + offset;
@ -651,8 +651,8 @@ iommu_bus_dmamap_load_something(struct bus_dma_tag_iommu *tag,
{
struct iommu_ctx *ctx;
struct iommu_domain *domain;
struct iommu_map_entry *entry, *entry1;
struct iommu_map_entries_tailq unroll_list;
struct iommu_map_entry *entry;
struct iommu_map_entries_tailq entries, unroll_list;
int error;
ctx = tag->ctx;
@ -662,15 +662,15 @@ iommu_bus_dmamap_load_something(struct bus_dma_tag_iommu *tag,
TAILQ_INIT(&unroll_list);
error = iommu_bus_dmamap_load_something1(tag, map, ma, offset,
buflen, flags, segs, segp, &unroll_list);
if (error != 0) {
if (error != 0 && !TAILQ_EMPTY(&unroll_list)) {
/*
* The busdma interface does not allow us to report
* partial buffer load, so unfortunately we have to
* revert all work done.
*/
IOMMU_DOMAIN_LOCK(domain);
TAILQ_FOREACH_SAFE(entry, &unroll_list, unroll_link,
entry1) {
TAILQ_INIT(&entries);
IOMMU_DMAMAP_LOCK(map);
TAILQ_FOREACH(entry, &unroll_list, unroll_link) {
/*
* No entries other than what we have created
* during the failed run might have been
@ -678,10 +678,11 @@ iommu_bus_dmamap_load_something(struct bus_dma_tag_iommu *tag,
* pglock.
*/
TAILQ_REMOVE(&map->map_entries, entry, dmamap_link);
TAILQ_REMOVE(&unroll_list, entry, unroll_link);
TAILQ_INSERT_TAIL(&domain->unload_entries, entry,
dmamap_link);
TAILQ_INSERT_TAIL(&entries, entry, dmamap_link);
}
IOMMU_DMAMAP_UNLOCK(map);
IOMMU_DOMAIN_LOCK(domain);
TAILQ_CONCAT(&domain->unload_entries, &entries, dmamap_link);
IOMMU_DOMAIN_UNLOCK(domain);
taskqueue_enqueue(domain->iommu->delayed_taskqueue,
&domain->unload_task);
@ -872,9 +873,7 @@ iommu_bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map1)
struct bus_dmamap_iommu *map;
struct iommu_ctx *ctx;
struct iommu_domain *domain;
#ifndef IOMMU_DOMAIN_UNLOAD_SLEEP
struct iommu_map_entries_tailq entries;
#endif
tag = (struct bus_dma_tag_iommu *)dmat;
map = (struct bus_dmamap_iommu *)map1;
@ -882,17 +881,17 @@ iommu_bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map1)
domain = ctx->domain;
atomic_add_long(&ctx->unloads, 1);
TAILQ_INIT(&entries);
IOMMU_DMAMAP_LOCK(map);
TAILQ_CONCAT(&entries, &map->map_entries, dmamap_link);
IOMMU_DMAMAP_UNLOCK(map);
#if defined(IOMMU_DOMAIN_UNLOAD_SLEEP)
IOMMU_DOMAIN_LOCK(domain);
TAILQ_CONCAT(&domain->unload_entries, &map->map_entries, dmamap_link);
TAILQ_CONCAT(&domain->unload_entries, &entries, dmamap_link);
IOMMU_DOMAIN_UNLOCK(domain);
taskqueue_enqueue(domain->iommu->delayed_taskqueue,
&domain->unload_task);
#else
TAILQ_INIT(&entries);
IOMMU_DOMAIN_LOCK(domain);
TAILQ_CONCAT(&entries, &map->map_entries, dmamap_link);
IOMMU_DOMAIN_UNLOCK(domain);
THREAD_NO_SLEEPING();
iommu_domain_unload(domain, &entries, false);
THREAD_SLEEPING_OK();
@ -1062,13 +1061,12 @@ bus_dma_iommu_load_ident(bus_dma_tag_t dmat, bus_dmamap_t map1,
VM_MEMATTR_DEFAULT);
}
error = iommu_gas_map_region(domain, entry, IOMMU_MAP_ENTRY_READ |
((flags & BUS_DMA_NOWRITE) ? 0 : IOMMU_MAP_ENTRY_WRITE),
waitok ? IOMMU_MF_CANWAIT : 0, ma);
((flags & BUS_DMA_NOWRITE) ? 0 : IOMMU_MAP_ENTRY_WRITE) |
IOMMU_MAP_ENTRY_MAP, waitok ? IOMMU_MF_CANWAIT : 0, ma);
if (error == 0) {
IOMMU_DOMAIN_LOCK(domain);
IOMMU_DMAMAP_LOCK(map);
TAILQ_INSERT_TAIL(&map->map_entries, entry, dmamap_link);
entry->flags |= IOMMU_MAP_ENTRY_MAP;
IOMMU_DOMAIN_UNLOCK(domain);
IOMMU_DMAMAP_UNLOCK(map);
} else {
iommu_domain_unload_entry(entry, true);
}

7
sys/dev/iommu/busdma_iommu.h
View File

@ -49,6 +49,7 @@ struct bus_dmamap_iommu {
struct memdesc mem;
bus_dmamap_callback_t *callback;
void *callback_arg;
struct mtx lock;
struct iommu_map_entries_tailq map_entries;
TAILQ_ENTRY(bus_dmamap_iommu) delay_link;
bool locked;
@ -59,6 +60,12 @@ struct bus_dmamap_iommu {
#endif
};
#define IOMMU_DMAMAP_INIT(map) mtx_init(&(map)->lock, \
"iommu dmamap", NULL, MTX_DEF)
#define IOMMU_DMAMAP_DESTROY(map) mtx_destroy(&(map)->lock)
#define IOMMU_DMAMAP_LOCK(map) mtx_lock(&(map)->lock)
#define IOMMU_DMAMAP_UNLOCK(map) mtx_unlock(&(map)->lock)
#define BUS_DMAMAP_IOMMU_MALLOC 0x0001
#define BUS_DMAMAP_IOMMU_KMEM_ALLOC 0x0002