io_uring: introduce io_cache_free() helper

Add a helper function io_cache_free() that returns an allocation to a
io_alloc_cache, falling back on kfree() if the io_alloc_cache is full.
This is the inverse of io_cache_alloc(), which takes an allocation from
an io_alloc_cache and falls back on kmalloc() if the cache is empty.

Convert 4 callers to use the helper.

Signed-off-by: Caleb Sander Mateos <[email protected]>
Suggested-by: Li Zetao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: calebsander

io_uring/alloc_cache.h

@@ -68,4 +68,10 @@ static inline void *io_cache_alloc(struct io_alloc_cache *cache, gfp_t gfp)
 	return io_cache_alloc_new(cache, gfp);
 }
 
+static inline void io_cache_free(struct io_alloc_cache *cache, void *obj)
+{
+	if (!io_alloc_cache_put(cache, obj))
+		kfree(obj);
+}
+
 #endif

io_uring/futex.c

@@ -53,12 +53,10 @@ static void __io_futex_complete(struct io_kiocb *req, io_tw_token_t tw)
 
 static void io_futex_complete(struct io_kiocb *req, io_tw_token_t tw)
 {
-	struct io_futex_data *ifd = req->async_data;
 	struct io_ring_ctx *ctx = req->ctx;
 
 	io_tw_lock(ctx, tw);
-	if (!io_alloc_cache_put(&ctx->futex_cache, ifd))
-		kfree(ifd);
+	io_cache_free(&ctx->futex_cache, req->async_data);
 	__io_futex_complete(req, tw);
 }
 

io_uring/io_uring.c

@@ -1422,8 +1422,7 @@ 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))
-					kfree(apoll);
+				io_cache_free(&ctx->apoll_cache, apoll);
 				req->flags &= ~REQ_F_POLLED;
 			}
 			if (req->flags & IO_REQ_LINK_FLAGS)

io_uring/rsrc.c

@@ -124,8 +124,9 @@ static struct io_mapped_ubuf *io_alloc_imu(struct io_ring_ctx *ctx,
 
 static void io_free_imu(struct io_ring_ctx *ctx, struct io_mapped_ubuf *imu)
 {
-	if (imu->nr_bvecs > IO_CACHED_BVECS_SEGS ||
-	    !io_alloc_cache_put(&ctx->imu_cache, imu))
+	if (imu->nr_bvecs <= IO_CACHED_BVECS_SEGS)
+		io_cache_free(&ctx->imu_cache, imu);
+	else
 		kvfree(imu);
 }
 
@@ -487,12 +488,6 @@ int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
-static void io_free_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
-{
-	if (!io_alloc_cache_put(&ctx->node_cache, node))
-		kfree(node);
-}
-
 void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 {
 	if (node->tag)
@@ -510,7 +505,7 @@ void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 		break;
 	}
 
-	io_free_node(ctx, node);
+	io_cache_free(&ctx->node_cache, node);
 }
 
 int io_sqe_files_unregister(struct io_ring_ctx *ctx)
@@ -835,7 +830,7 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
 	if (ret) {
 		if (imu)
 			io_free_imu(ctx, imu);
-		io_free_node(ctx, node);
+		io_cache_free(&ctx->node_cache, node);
 		node = ERR_PTR(ret);
 	}
 	kvfree(pages);