[PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[Nam Cao]

In nvme_tcp_ddgst_update(), sg_init_marker() is called with an
uninitialized scatterlist. This is probably fine, but gcc complains:

  CC [M]  drivers/nvme/host/tcp.o
In file included from ./include/linux/dma-mapping.h:10,
                 from ./include/linux/skbuff.h:31,
                 from ./include/net/net_namespace.h:43,
                 from ./include/linux/netdevice.h:38,
                 from ./include/net/sock.h:46,
                 from drivers/nvme/host/tcp.c:12:
In function ‘sg_mark_end’,
    inlined from ‘sg_init_marker’ at ./include/linux/scatterlist.h:356:2,
    inlined from ‘nvme_tcp_ddgst_update’ at drivers/nvme/host/tcp.c:390:2:
./include/linux/scatterlist.h:234:11: error: ‘sg.page_link’ is used uninitialized [-Werror=uninitialized]
  234 |         sg->page_link |= SG_END;
      |         ~~^~~~~~~~~~~
drivers/nvme/host/tcp.c: In function ‘nvme_tcp_ddgst_update’:
drivers/nvme/host/tcp.c:388:28: note: ‘sg’ declared here
  388 |         struct scatterlist sg;
      |                            ^~
cc1: all warnings being treated as errors

Use sg_init_table() instead, which basically memset the scatterlist to
zero first before calling sg_init_marker().

Signed-off-by: Nam Cao <namcaov@gmail.com>
---
 drivers/nvme/host/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1eed0fc26b3a..dc2def86076d 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -387,7 +387,7 @@ static inline void nvme_tcp_ddgst_update(struct ahash_request *hash,
 {
 	struct scatterlist sg;
 
-	sg_init_marker(&sg, 1);
+	sg_init_table(&sg, 1);
 	sg_set_page(&sg, page, len, off);
 	ahash_request_set_crypt(hash, &sg, NULL, len);
 	crypto_ahash_update(hash);
-- 
2.25.1

Re: [PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[Sagi Grimberg]

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Re: [PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[Chaitanya Kulkarni]

On 10/22/22 10:46, Nam Cao wrote:
> In nvme_tcp_ddgst_update(), sg_init_marker() is called with an
> uninitialized scatterlist. This is probably fine, but gcc complains:
> 
>    CC [M]  drivers/nvme/host/tcp.o
> In file included from ./include/linux/dma-mapping.h:10,
>                   from ./include/linux/skbuff.h:31,
>                   from ./include/net/net_namespace.h:43,
>                   from ./include/linux/netdevice.h:38,
>                   from ./include/net/sock.h:46,
>                   from drivers/nvme/host/tcp.c:12:
> In function ‘sg_mark_end’,
>      inlined from ‘sg_init_marker’ at ./include/linux/scatterlist.h:356:2,
>      inlined from ‘nvme_tcp_ddgst_update’ at drivers/nvme/host/tcp.c:390:2:
> ./include/linux/scatterlist.h:234:11: error: ‘sg.page_link’ is used uninitialized [-Werror=uninitialized]
>    234 |         sg->page_link |= SG_END;
>        |         ~~^~~~~~~~~~~
> drivers/nvme/host/tcp.c: In function ‘nvme_tcp_ddgst_update’:
> drivers/nvme/host/tcp.c:388:28: note: ‘sg’ declared here
>    388 |         struct scatterlist sg;
>        |                            ^~
> cc1: all warnings being treated as errors
> 
> Use sg_init_table() instead, which basically memset the scatterlist to
> zero first before calling sg_init_marker().
> 
> Signed-off-by: Nam Cao <namcaov@gmail.com>

Looks good to me, can you please share what version if gcc you are
using ? my test setup did not catch this error and I'd like to update
with the one that can catch these errors.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[Nam Cao]

On Tue, Oct 25, 2022 at 12:58:41AM +0000, Chaitanya Kulkarni wrote:
> On 10/22/22 10:46, Nam Cao wrote:
> > In nvme_tcp_ddgst_update(), sg_init_marker() is called with an
> > uninitialized scatterlist. This is probably fine, but gcc complains:
> > 
> >    CC [M]  drivers/nvme/host/tcp.o
> > In file included from ./include/linux/dma-mapping.h:10,
> >                   from ./include/linux/skbuff.h:31,
> >                   from ./include/net/net_namespace.h:43,
> >                   from ./include/linux/netdevice.h:38,
> >                   from ./include/net/sock.h:46,
> >                   from drivers/nvme/host/tcp.c:12:
> > In function ‘sg_mark_end’,
> >      inlined from ‘sg_init_marker’ at ./include/linux/scatterlist.h:356:2,
> >      inlined from ‘nvme_tcp_ddgst_update’ at drivers/nvme/host/tcp.c:390:2:
> > ./include/linux/scatterlist.h:234:11: error: ‘sg.page_link’ is used uninitialized [-Werror=uninitialized]
> >    234 |         sg->page_link |= SG_END;
> >        |         ~~^~~~~~~~~~~
> > drivers/nvme/host/tcp.c: In function ‘nvme_tcp_ddgst_update’:
> > drivers/nvme/host/tcp.c:388:28: note: ‘sg’ declared here
> >    388 |         struct scatterlist sg;
> >        |                            ^~
> > cc1: all warnings being treated as errors
> > 
> > Use sg_init_table() instead, which basically memset the scatterlist to
> > zero first before calling sg_init_marker().
> > 
> > Signed-off-by: Nam Cao <namcaov@gmail.com>
> 
> Looks good to me, can you please share what version if gcc you are
> using ? my test setup did not catch this error and I'd like to update
> with the one that can catch these errors.

It was just gcc12. But strange enough I cannot trigger this error again.
I was doing randconfig test build. Probably only a specific combination
of configs that can allow gcc to detect this...

And sorry but I was just start doing randconfig test and didn't think
about saving that .config file.

Best regards,
Nam

Re: [PATCH] nvme-tcp: replace sg_init_marker() with sg_init_table()

[Christoph Hellwig]

Thanks,

applied to nvme-6.1.