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, 4 insertions, 10 deletions

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 92346b5d9f5b..334d31dd6628 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -11,18 +11,17 @@
 #include <asm/ioctls.h>
 
 #include "io_uring.h"
+#include "alloc_cache.h"
 #include "rsrc.h"
 #include "uring_cmd.h"
 
 static struct uring_cache *io_uring_async_get(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	struct io_cache_entry *entry;
 	struct uring_cache *cache;
 
-	entry = io_alloc_cache_get(&ctx->uring_cache);
-	if (entry) {
-		cache = container_of(entry, struct uring_cache, cache);
+	cache = io_alloc_cache_get(&ctx->uring_cache);
+	if (cache) {
 		req->flags |= REQ_F_ASYNC_DATA;
 		req->async_data = cache;
 		return cache;
@@ -39,7 +38,7 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (issue_flags & IO_URING_F_UNLOCKED)
 		return;
-	if (io_alloc_cache_put(&req->ctx->uring_cache, &cache->cache)) {
+	if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
 		ioucmd->sqe = NULL;
 		req->async_data = NULL;
 		req->flags &= ~REQ_F_ASYNC_DATA;
@@ -354,8 +353,3 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
 #endif
-
-void io_uring_cache_free(struct io_cache_entry *entry)
-{
-	kfree(container_of(entry, struct uring_cache, cache));
-}