io_uring/rsrc: kill rsrc_ref_lock

We use ->rsrc_ref_lock spinlock to protect ->rsrc_ref_list in
io_rsrc_node_ref_zero(). Now we removed pcpu refcounting, which means
io_rsrc_node_ref_zero() is not executed from the irq context as an RCU
callback anymore, and we also put it under ->uring_lock.
io_rsrc_node_switch(), which queues up nodes into the list, is also
protected by ->uring_lock, so we can safely get rid of ->rsrc_ref_lock.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6b60af883c263551190b526a55ff2c9d5ae07141.1680576071.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index a0a5b59..9492889 100644 (file)
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -333,8 +333,8 @@ struct io_ring_ctx {
        struct delayed_work             rsrc_put_work;
        struct callback_head            rsrc_put_tw;
        struct llist_head               rsrc_put_llist;
+       /* protected by ->uring_lock */
        struct list_head                rsrc_ref_list;
-       spinlock_t                      rsrc_ref_lock;
 
        struct list_head                io_buffers_pages;
 

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 36a76c7..764df56 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -325,7 +325,6 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
        INIT_LIST_HEAD(&ctx->defer_list);
        INIT_LIST_HEAD(&ctx->timeout_list);
        INIT_LIST_HEAD(&ctx->ltimeout_list);
-       spin_lock_init(&ctx->rsrc_ref_lock);
        INIT_LIST_HEAD(&ctx->rsrc_ref_list);
        INIT_DELAYED_WORK(&ctx->rsrc_put_work, io_rsrc_put_work);
        init_task_work(&ctx->rsrc_put_tw, io_rsrc_put_tw);

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 1237fc7..e122b6e 100644 (file)
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -209,11 +209,9 @@ void io_rsrc_node_ref_zero(struct io_rsrc_node *node)
        __must_hold(&node->rsrc_data->ctx->uring_lock)
 {
        struct io_ring_ctx *ctx = node->rsrc_data->ctx;
-       unsigned long flags;
        bool first_add = false;
        unsigned long delay = HZ;
 
-       spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
        node->done = true;
 
        /* if we are mid-quiesce then do not delay */
@@ -229,7 +227,6 @@ void io_rsrc_node_ref_zero(struct io_rsrc_node *node)
                list_del(&node->node);
                first_add |= llist_add(&node->llist, &ctx->rsrc_put_llist);
        }
-       spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags);
 
        if (!first_add)
                return;
@@ -268,9 +265,7 @@ void io_rsrc_node_switch(struct io_ring_ctx *ctx,
                struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
 
                rsrc_node->rsrc_data = data_to_kill;
-               spin_lock_irq(&ctx->rsrc_ref_lock);
                list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
-               spin_unlock_irq(&ctx->rsrc_ref_lock);
 
                atomic_inc(&data_to_kill->refs);
                /* put master ref */