From 892d3e80e1b9fc09aefdfd4d31f10f3d018863a0 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 16 Oct 2024 15:48:38 -0600 Subject: [PATCH] io_uring/uring_cmd: get rid of using req->imu It's pretty pointless to use io_kiocb as intermediate storage for this, so split the validity check and the actual usage. The resource node is assigned upfront at prep time, to prevent it from going away. The actual import is never called with the ctx->uring_lock held, so grab it for the import. Signed-off-by: Jens Axboe --- io_uring/uring_cmd.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index 39c3c816ec78..58d0b817d6ea 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -211,11 +211,15 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) struct io_ring_ctx *ctx = req->ctx; u16 index; - req->buf_index = READ_ONCE(sqe->buf_index); - if (unlikely(req->buf_index >= ctx->nr_user_bufs)) + index = READ_ONCE(sqe->buf_index); + if (unlikely(index >= ctx->nr_user_bufs)) return -EFAULT; - index = array_index_nospec(req->buf_index, ctx->nr_user_bufs); - req->imu = ctx->user_bufs[index]; + req->buf_index = array_index_nospec(index, ctx->nr_user_bufs); + /* + * Pi node upfront, prior to io_uring_cmd_import_fixed() + * being called. This prevents destruction of the mapped buffer + * we'll need at actual import time. + */ io_req_set_rsrc_node(req, ctx, 0); } ioucmd->cmd_op = READ_ONCE(sqe->cmd_op); @@ -272,8 +276,17 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, struct iov_iter *iter, void *ioucmd) { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); + struct io_ring_ctx *ctx = req->ctx; - return io_import_fixed(rw, iter, req->imu, ubuf, len); + /* Must have had rsrc_node assigned at prep time */ + if (req->rsrc_node) { + struct io_mapped_ubuf *imu; + + imu = READ_ONCE(ctx->user_bufs[req->buf_index]); + return io_import_fixed(rw, iter, imu, ubuf, len); + } + + return -EFAULT; } EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);