Subject: Re: linux-next: build warning after merge of the block tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 15 Jul 2022 22:33:51 +1000

Hi all,

On Fri, 15 Jul 2022 13:52:32 +1000 Stephen Rothwell <[email-masked]> wrote:
> 
> After merging the block tree, today's linux-next build (arm
> multi_v7_defconfig) produced this warning:
> 
> In file included from include/linux/slab.h:16,
>                  from io_uring/net.c:5:
> io_uring/net.c: In function 'io_recvmsg_multishot_overflow':
> include/linux/overflow.h:67:22: warning: comparison of distinct pointer types lacks a cast
>    67 |         (void) (&__a == &__b);                  \
>       |                      ^~
> io_uring/net.c:332:13: note: in expansion of macro 'check_add_overflow'
>   332 |         if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
>       |             ^~~~~~~~~~~~~~~~~~
> include/linux/overflow.h:68:22: warning: comparison of distinct pointer types lacks a cast
>    68 |         (void) (&__a == __d);                   \
>       |                      ^~
> io_uring/net.c:332:13: note: in expansion of macro 'check_add_overflow'
>   332 |         if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
>       |             ^~~~~~~~~~~~~~~~~~
> include/linux/overflow.h:67:22: warning: comparison of distinct pointer types lacks a cast
>    67 |         (void) (&__a == &__b);                  \
>       |                      ^~
> io_uring/net.c:335:13: note: in expansion of macro 'check_add_overflow'
>   335 |         if (check_add_overflow(hdr, iomsg->controllen, &hdr))
>       |             ^~~~~~~~~~~~~~~~~~
> 
> Introduced by commit
> 
>   a8b38c4ce724 ("io_uring: support multishot in recvmsg")

This became a build failure in my i386 defconfig build.  So I have
applied the following (probably not correct) patch that makes it build.

From: Stephen Rothwell <[email-masked]>
Date: Fri, 15 Jul 2022 21:55:32 +1000
Subject: [PATCH] fix up for "io_uring: support multishot in recvmsg"

Signed-off-by: Stephen Rothwell <[email-masked]>
---
 io_uring/net.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 616d5f04cc74..187822e18dd6 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -329,10 +329,10 @@ static bool io_recvmsg_multishot_overflow(struct io_async_msghdr *iomsg)
 {
 	unsigned long hdr;
 
-	if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
+	if (check_add_overflow((unsigned long)sizeof(struct io_uring_recvmsg_out),
 			       (unsigned long)iomsg->namelen, &hdr))
 		return true;
-	if (check_add_overflow(hdr, iomsg->controllen, &hdr))
+	if (check_add_overflow(hdr, (unsigned long)iomsg->controllen, &hdr))
 		return true;
 	if (hdr > INT_MAX)
 		return true;
-- 
2.35.1

-- 
Cheers,
Stephen Rothwell