linux-kernel - [PATCH v2 3/3] io_uring: Remove unnecessary BUILD_BUG

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Message-Id: <20230421114440.3343473-4-leitao@debian.org>
Date:   Fri, 21 Apr 2023 04:44:40 -0700
From:   Breno Leitao <leitao@...ian.org>
To:     io-uring@...r.kernel.org, linux-nvme@...ts.infradead.org,
        asml.silence@...il.com, axboe@...nel.dk
Cc:     leit@...com, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, sagi@...mberg.me, hch@....de,
        kbusch@...nel.org, ming.lei@...hat.com
Subject: [PATCH v2 3/3] io_uring: Remove unnecessary BUILD_BUG_ON

In the io_uring_cmd_prep_async() there is a unnecessary compilation time
check to check if cmd is correctly placed at field 48 of the SQE.

This is uncessary, since this check is already in place at
io_uring_init():

          BUILD_BUG_SQE_ELEM(48, __u64,  addr3);

Remove it and the uring_cmd_pdu_size() function, which is not used
anymore.

Keith started a discussion about this topic in the following thread:
https://lore.kernel.org/lkml/ZDBmQOhbyU0iLhMw@kbusch-mbp.dhcp.thefacebook.com/

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 io_uring/uring_cmd.c | 3 ---
 io_uring/uring_cmd.h | 8 --------
 2 files changed, 11 deletions(-)

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index a1be746cd009..743d1496431b 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -71,9 +71,6 @@ int io_uring_cmd_prep_async(struct io_kiocb *req)
 	struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
 	size_t size = uring_sqe_size(req->ctx);
 
-	BUILD_BUG_ON(uring_cmd_pdu_size(0) != 16);
-	BUILD_BUG_ON(uring_cmd_pdu_size(1) != 80);
-
 	memcpy(req->async_data, ioucmd->sqe, size);
 	ioucmd->sqe = req->async_data;
 	return 0;
diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
index 7c6697d13cb2..8117684ec3ca 100644
--- a/io_uring/uring_cmd.h
+++ b/io_uring/uring_cmd.h
@@ -3,11 +3,3 @@
 int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
 int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_uring_cmd_prep_async(struct io_kiocb *req);
-
-/*
- * The URING_CMD payload starts at 'cmd' in the first sqe, and continues into
- * the following sqe if SQE128 is used.
- */
-#define uring_cmd_pdu_size(is_sqe128)				\
-	((1 + !!(is_sqe128)) * sizeof(struct io_uring_sqe) -	\
-		offsetof(struct io_uring_sqe, cmd))
-- 
2.34.1