io_uring/alloc_cache: switch to array based caching

Currently lists are being used to manage this, but best practice is
usually to have these in an array instead as that it cheaper to manage.

Outside of that detail, games are also played with KASAN as the list
is inside the cached entry itself.

Finally, all users of this need a struct io_cache_entry embedded in
their struct, which is union'ized with something else in there that
isn't used across the free -> realloc cycle.

Get rid of all of that, and simply have it be an array. This will not
change the memory used, as we're just trading an 8-byte member entry
for the per-elem array size.

This reduces the overhead of the recycled allocations, and it reduces
the amount of code code needed to support recycling to about half of
what it currently is.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 19 insertions, 15 deletions

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 579618fad833..1d453eb8e49f 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -276,6 +276,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 {
 	struct io_ring_ctx *ctx;
 	int hash_bits;
+	bool ret;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -305,17 +306,19 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_LIST_HEAD(&ctx->cq_overflow_list);
 	INIT_LIST_HEAD(&ctx->io_buffers_cache);
 	INIT_HLIST_HEAD(&ctx->io_buf_list);
-	io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
+	ret = io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
 			    sizeof(struct io_rsrc_node));
-	io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
+	ret |= io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct async_poll));
-	io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
+	ret |= io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct io_async_msghdr));
-	io_alloc_cache_init(&ctx->rw_cache, IO_ALLOC_CACHE_MAX,
+	ret |= io_alloc_cache_init(&ctx->rw_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct io_async_rw));
-	io_alloc_cache_init(&ctx->uring_cache, IO_ALLOC_CACHE_MAX,
+	ret |= io_alloc_cache_init(&ctx->uring_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct uring_cache));
-	io_futex_cache_init(ctx);
+	ret |= io_futex_cache_init(ctx);
+	if (ret)
+		goto err;
 	init_completion(&ctx->ref_comp);
 	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
 	mutex_init(&ctx->uring_lock);
@@ -345,6 +348,12 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 
 	return ctx;
 err:
+	io_alloc_cache_free(&ctx->rsrc_node_cache, kfree);
+	io_alloc_cache_free(&ctx->apoll_cache, kfree);
+	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
+	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
+	io_alloc_cache_free(&ctx->uring_cache, kfree);
+	io_futex_cache_free(ctx);
 	kfree(ctx->cancel_table.hbs);
 	kfree(ctx->cancel_table_locked.hbs);
 	xa_destroy(&ctx->io_bl_xa);
@@ -1482,7 +1491,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
 
 				if (apoll->double_poll)
 					kfree(apoll->double_poll);
-				if (!io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache))
+				if (!io_alloc_cache_put(&ctx->apoll_cache, apoll))
 					kfree(apoll);
 				req->flags &= ~REQ_F_POLLED;
 			}
@@ -2778,11 +2787,6 @@ static void io_req_caches_free(struct io_ring_ctx *ctx)
 	mutex_unlock(&ctx->uring_lock);
 }
 
-static void io_rsrc_node_cache_free(struct io_cache_entry *entry)
-{
-	kfree(container_of(entry, struct io_rsrc_node, cache));
-}
-
 static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 {
 	io_sq_thread_finish(ctx);
@@ -2797,10 +2801,10 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 		__io_sqe_files_unregister(ctx);
 	io_cqring_overflow_kill(ctx);
 	io_eventfd_unregister(ctx);
-	io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
+	io_alloc_cache_free(&ctx->apoll_cache, kfree);
 	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
 	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
-	io_alloc_cache_free(&ctx->uring_cache, io_uring_cache_free);
+	io_alloc_cache_free(&ctx->uring_cache, kfree);
 	io_futex_cache_free(ctx);
 	io_destroy_buffers(ctx);
 	mutex_unlock(&ctx->uring_lock);
@@ -2816,7 +2820,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
 	WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
 
-	io_alloc_cache_free(&ctx->rsrc_node_cache, io_rsrc_node_cache_free);
+	io_alloc_cache_free(&ctx->rsrc_node_cache, kfree);
 	if (ctx->mm_account) {
 		mmdrop(ctx->mm_account);
 		ctx->mm_account = NULL;