Commit 90175f3f authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/kbuf: remove pbuf ring refcounting 



struct io_buffer_list refcounting was needed for RCU based sync with
mmap, now  we can kill it.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4a9cc54bf0077bb2bf2f3daf917549ddd41080da.1732886067.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 78fda3d0

io_uring/kbuf.c

+7 −14
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ static int io_buffer_add_list(struct io_ring_ctx *ctx, 
	 * always under the ->uring_lock, but lookups from mmap do.

	 */

	bl->bgid = bgid;

	atomic_set(&bl->refs, 1);

	guard(mutex)(&ctx->mmap_lock);

	return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));

}
@@ -385,13 +384,11 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx, 
	return i;

}



void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)

static void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)

{

	if (atomic_dec_and_test(&bl->refs)) {

	__io_remove_buffers(ctx, bl, -1U);

	kfree(bl);

}

}



void io_destroy_buffers(struct io_ring_ctx *ctx)

{
@@ -804,10 +801,8 @@ struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx, 


	bl = xa_load(&ctx->io_bl_xa, bgid);

	/* must be a mmap'able buffer ring and have pages */

	if (bl && bl->flags & IOBL_MMAP) {

		if (atomic_inc_not_zero(&bl->refs))

	if (bl && bl->flags & IOBL_MMAP)

		return bl;

	}



	return ERR_PTR(-EINVAL);

}
@@ -817,7 +812,7 @@ int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma) 
	struct io_ring_ctx *ctx = file->private_data;

	loff_t pgoff = vma->vm_pgoff << PAGE_SHIFT;

	struct io_buffer_list *bl;

	int bgid, ret;

	int bgid;



	lockdep_assert_held(&ctx->mmap_lock);
@@ -826,7 +821,5 @@ int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma) 
	if (IS_ERR(bl))

		return PTR_ERR(bl);



	ret = io_uring_mmap_pages(ctx, vma, bl->buf_pages, bl->buf_nr_pages);

	io_put_bl(ctx, bl);

	return ret;

	return io_uring_mmap_pages(ctx, vma, bl->buf_pages, bl->buf_nr_pages);

}

io_uring/kbuf.h

+0 −3
Original line number Diff line number Diff line
@@ -35,8 +35,6 @@ struct io_buffer_list { 
	__u16 mask;



	__u16 flags;



	atomic_t refs;

};



struct io_buffer {
@@ -83,7 +81,6 @@ void __io_put_kbuf(struct io_kiocb *req, int len, unsigned issue_flags); 


bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags);



void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl);

struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx,

				      unsigned long bgid);

int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma);

io_uring/memmap.c

+0 −1
Original line number Diff line number Diff line
@@ -383,7 +383,6 @@ static void *io_uring_validate_mmap_request(struct file *file, loff_t pgoff, 
		if (IS_ERR(bl))

			return bl;

		ptr = bl->buf_ring;

		io_put_bl(ctx, bl);

		return ptr;

		}

	case IORING_MAP_OFF_PARAM_REGION: