[PATCH 7/8] io_uring/rsrc: refactor io_rsrc_node_switch

Pavel Begunkov
2023-04-11T11:13:19Z

We use io_rsrc_node_switch() coupled with io_rsrc_node_switch_start()
for a bunch of cases including initialising ctx->rsrc_node, i.e. by
passing NULL instead of rsrc_data. Leave it to only deal with actual
node changing.

For that, first remove it from io_uring_create() and add a function
allocating the first node. Then also remove all calls to
io_rsrc_node_switch() from files/buffers register as we already have a
node installed and it does essentially nothing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
io_uring/io_uring.c | 5 ++---
io_uring/rsrc.c | 36 +++++++++++-------------------------
io_uring/rsrc.h | 7 +++++++
3 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 075bae8a2bb1..9083a8466ebf 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3881,11 +3881,10 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
ret = io_sq_offload_create(ctx, p);
if (ret)
goto err;
- /* always set a rsrc node */
- ret = io_rsrc_node_switch_start(ctx);
+
+ ret = io_rsrc_init(ctx);
if (ret)
goto err;
- io_rsrc_node_switch(ctx, NULL);

memset(&p->sq_off, 0, sizeof(p->sq_off));
p->sq_off.head = offsetof(struct io_rings, sq.head);
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 329cc3851dfd..f2c660ffea74 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -204,7 +204,7 @@ void io_rsrc_node_ref_zero(struct io_rsrc_node *node)
}
}

-static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx)
+struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx)
{
struct io_rsrc_node *ref_node;
struct io_cache_entry *entry;
@@ -231,23 +231,18 @@ void io_rsrc_node_switch(struct io_ring_ctx *ctx,
struct io_rsrc_data *data_to_kill)
__must_hold(&ctx->uring_lock)
{
- WARN_ON_ONCE(io_alloc_cache_empty(&ctx->rsrc_node_cache));
- WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node);
+ struct io_rsrc_node *node = ctx->rsrc_node;
+ struct io_rsrc_node *backup = io_rsrc_node_alloc(ctx);

- if (data_to_kill) {
- struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
-
- rsrc_node->rsrc_data = data_to_kill;
- list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
-
- data_to_kill->refs++;
- /* put master ref */
- io_put_rsrc_node(ctx, rsrc_node);
- ctx->rsrc_node = NULL;
- }
+ if (WARN_ON_ONCE(!backup))
+ return;

- if (!ctx->rsrc_node)
- ctx->rsrc_node = io_rsrc_node_alloc(ctx);
+ data_to_kill->refs++;
+ node->rsrc_data = data_to_kill;
+ list_add_tail(&node->node, &ctx->rsrc_ref_list);
+ /* put master ref */
+ io_put_rsrc_node(ctx, node);
+ ctx->rsrc_node = backup;
}

int io_rsrc_node_switch_start(struct io_ring_ctx *ctx)
@@ -921,9 +916,6 @@ int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
return -EMFILE;
if (nr_args > rlimit(RLIMIT_NOFILE))
return -EMFILE;
- ret = io_rsrc_node_switch_start(ctx);
- if (ret)
- return ret;
ret = io_rsrc_data_alloc(ctx, io_rsrc_file_put, tags, nr_args,
&ctx->file_data);
if (ret)
@@ -978,7 +970,6 @@ int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,

/* default it to the whole table */
io_file_table_set_alloc_range(ctx, 0, ctx->nr_user_files);
- io_rsrc_node_switch(ctx, NULL);
return 0;
fail:
__io_sqe_files_unregister(ctx);
@@ -1260,9 +1251,6 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
return -EBUSY;
if (!nr_args || nr_args > IORING_MAX_REG_BUFFERS)
return -EINVAL;
- ret = io_rsrc_node_switch_start(ctx);
- if (ret)
- return ret;
ret = io_rsrc_data_alloc(ctx, io_rsrc_buf_put, tags, nr_args, &data);
if (ret)
return ret;
@@ -1300,8 +1288,6 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
ctx->buf_data = data;
if (ret)
__io_sqe_buffers_unregister(ctx);
- else
- io_rsrc_node_switch(ctx, NULL);
return ret;
}

diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 8729f2fee256..17dfe180208f 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -74,6 +74,7 @@ void io_rsrc_put_work(struct work_struct *work);
void io_wait_rsrc_data(struct io_rsrc_data *data);
void io_rsrc_node_destroy(struct io_ring_ctx *ctx, struct io_rsrc_node *ref_node);
int io_rsrc_node_switch_start(struct io_ring_ctx *ctx);
+struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx);
int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
struct io_rsrc_node *node, void *rsrc);
void io_rsrc_node_switch(struct io_ring_ctx *ctx,
@@ -164,6 +165,12 @@ static inline u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
return &data->tags[table_idx][off];
}

+static inline int io_rsrc_init(struct io_ring_ctx *ctx)
+{
+ ctx->rsrc_node = io_rsrc_node_alloc(ctx);
+ return ctx->rsrc_node ? 0 : -ENOMEM;
+}
+
int io_files_update(struct io_kiocb *req, unsigned int issue_flags);
int io_files_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);

--
2.40.0