[PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Yoshihiro Shimoda]

Smatch detected the following warning.

    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
    '%pM' cannot be followed by 'n'

The 'n' should be '\n'.

Reported-by: Dan Carpenter <error27@gmail.com>
Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/net/ethernet/renesas/rswitch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index f3d27aef1286..51ce5c26631b 100644
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
 	}
 
 	for (i = 0; i < RSWITCH_NUM_PORTS; i++)
-		netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
+		netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
 			    priv->rdev[i]->ndev->dev_addr);
 
 	return 0;
-- 
2.25.1

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Saeed Mahameed]

On 16 Nov 08:55, Yoshihiro Shimoda wrote:
>Smatch detected the following warning.
>
>    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
>    '%pM' cannot be followed by 'n'
>
>The 'n' should be '\n'.
>
>Reported-by: Dan Carpenter <error27@gmail.com>
>Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
>Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")

I would drop the Fixes tag, this shoiuldn't go to net and -stable. 
and please tag either [PATCH net] or [PATCH net-next], this one should be
net-next.

Thanks,
you can add:
Reviewed-by: Saeed Mahameed <saeed@kernel.org>

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Vladimir Oltean]

On Wed, Nov 16, 2022 at 03:14:53PM -0800, Saeed Mahameed wrote:
> On 16 Nov 08:55, Yoshihiro Shimoda wrote:
> > Smatch detected the following warning.
> > 
> >    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> >    '%pM' cannot be followed by 'n'
> > 
> > The 'n' should be '\n'.
> > 
> > Reported-by: Dan Carpenter <error27@gmail.com>
> > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> 
> I would drop the Fixes tag, this shoiuldn't go to net and -stable. and
> please tag either [PATCH net] or [PATCH net-next], this one should be
> net-next.
> 
> Thanks,
> you can add:
> Reviewed-by: Saeed Mahameed <saeed@kernel.org>

You can have a Fixes: tag on a patch sent to net-next no problem.
No need to drop it. But in the future, using git-format-patch
--subject-prefix="PATCH net" (or net-next) would be indeed advisable.

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Dan Carpenter]

On Wed, Nov 16, 2022 at 03:14:53PM -0800, Saeed Mahameed wrote:
> On 16 Nov 08:55, Yoshihiro Shimoda wrote:
> > Smatch detected the following warning.
> > 
> >    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> >    '%pM' cannot be followed by 'n'
> > 
> > The 'n' should be '\n'.
> > 
> > Reported-by: Dan Carpenter <error27@gmail.com>
> > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> 
> I would drop the Fixes tag, this shoiuldn't go to net and -stable.

Some maintainers would want a Fixes tag for this and some wouldn't...
But either way Fixes doesn't really have to do with -stable.  In fact
sometimes the Fixes tag let's you automatically filter out fixes to code
which is newer than the -stable tree so it can mean the opposite of
-stable.

regards,
dan carpenter

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Dan Carpenter]

On Thu, Nov 17, 2022 at 06:58:19AM +0300, Dan Carpenter wrote:
> On Wed, Nov 16, 2022 at 03:14:53PM -0800, Saeed Mahameed wrote:
> > On 16 Nov 08:55, Yoshihiro Shimoda wrote:
> > > Smatch detected the following warning.
> > > 
> > >    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> > >    '%pM' cannot be followed by 'n'
> > > 
> > > The 'n' should be '\n'.
> > > 
> > > Reported-by: Dan Carpenter <error27@gmail.com>
> > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> > 
> > I would drop the Fixes tag, this shoiuldn't go to net and -stable.
> 
> Some maintainers would want a Fixes tag for this and some wouldn't...

Immediately after I sent this email a different maintainer asked me to
add a Fixes tag to a patch removing an unnecessary NULL check to silence
checker warning about inconsistent NULL checking.

Generally I would have put a Fixes tag here because the typo gets to the
users but I wouldn't put a Fixes tag for typos in the comments.

regards,
dan carpenter

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Leon Romanovsky]

On Wed, Nov 16, 2022 at 08:55:19AM +0900, Yoshihiro Shimoda wrote:
> Smatch detected the following warning.
> 
>     drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
>     '%pM' cannot be followed by 'n'
> 
> The 'n' should be '\n'.
> 
> Reported-by: Dan Carpenter <error27@gmail.com>
> Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  drivers/net/ethernet/renesas/rswitch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index f3d27aef1286..51ce5c26631b 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
>  	}
>  
>  	for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> -		netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> +		netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",

You can safely drop '\n' from here. It is not needed while printing one
line.

Thanks

>  			    priv->rdev[i]->ndev->dev_addr);
>  
>  	return 0;
> -- 
> 2.25.1
> 

RE: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Yoshihiro Shimoda]

Hi Vladimir,

> From: Vladimir Oltean, Sent: Thursday, November 17, 2022 8:36 AM
> 
> On Wed, Nov 16, 2022 at 03:14:53PM -0800, Saeed Mahameed wrote:
> > On 16 Nov 08:55, Yoshihiro Shimoda wrote:
> > > Smatch detected the following warning.
> > >
> > >    drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> > >    '%pM' cannot be followed by 'n'
> > >
> > > The 'n' should be '\n'.
> > >
> > > Reported-by: Dan Carpenter <error27@gmail.com>
> > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> >
> > I would drop the Fixes tag, this shoiuldn't go to net and -stable. and
> > please tag either [PATCH net] or [PATCH net-next], this one should be
> > net-next.
> >
> > Thanks,
> > you can add:
> > Reviewed-by: Saeed Mahameed <saeed@kernel.org>
> 
> You can have a Fixes: tag on a patch sent to net-next no problem.
> No need to drop it.

I got it.

> But in the future, using git-format-patch
> --subject-prefix="PATCH net" (or net-next) would be indeed advisable.

I'll send v2 patch by using --subject-prefix="PATCH v2 net-next".

Best regards,
Yoshihiro Shimoda

RE: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Yoshihiro Shimoda]

Hi Leon,

> From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> 
> On Wed, Nov 16, 2022 at 08:55:19AM +0900, Yoshihiro Shimoda wrote:
> > Smatch detected the following warning.
> >
> >     drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> >     '%pM' cannot be followed by 'n'
> >
> > The 'n' should be '\n'.
> >
> > Reported-by: Dan Carpenter <error27@gmail.com>
> > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > ---
> >  drivers/net/ethernet/renesas/rswitch.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> > index f3d27aef1286..51ce5c26631b 100644
> > --- a/drivers/net/ethernet/renesas/rswitch.c
> > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> >  	}
> >
> >  	for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > -		netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > +		netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> 
> You can safely drop '\n' from here. It is not needed while printing one
> line.

Oh, I didn't know that. I'll remove '\n' from here on v2 patch.

Best regards,
Yoshihiro Shimoda

> Thanks
> 
> >  			    priv->rdev[i]->ndev->dev_addr);
> >
> >  	return 0;
> > --
> > 2.25.1
> >

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Geert Uytterhoeven]

Hi Shimoda-san,

On Thu, Nov 17, 2022 at 9:58 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> > From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> > On Wed, Nov 16, 2022 at 08:55:19AM +0900, Yoshihiro Shimoda wrote:
> > > Smatch detected the following warning.
> > >
> > >     drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> > >     '%pM' cannot be followed by 'n'
> > >
> > > The 'n' should be '\n'.
> > >
> > > Reported-by: Dan Carpenter <error27@gmail.com>
> > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > > ---
> > >  drivers/net/ethernet/renesas/rswitch.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> > > index f3d27aef1286..51ce5c26631b 100644
> > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > >     }
> > >
> > >     for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > > -           netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > > +           netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> >
> > You can safely drop '\n' from here. It is not needed while printing one
> > line.
>
> Oh, I didn't know that. I'll remove '\n' from here on v2 patch.

Please don't remove it.  The convention is to have the newlines.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Leon Romanovsky]

On Thu, Nov 17, 2022 at 09:59:55AM +0100, Geert Uytterhoeven wrote:
> Hi Shimoda-san,
> 
> On Thu, Nov 17, 2022 at 9:58 AM Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@renesas.com> wrote:
> > > From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> > > On Wed, Nov 16, 2022 at 08:55:19AM +0900, Yoshihiro Shimoda wrote:
> > > > Smatch detected the following warning.
> > > >
> > > >     drivers/net/ethernet/renesas/rswitch.c:1717 rswitch_init() warn:
> > > >     '%pM' cannot be followed by 'n'
> > > >
> > > > The 'n' should be '\n'.
> > > >
> > > > Reported-by: Dan Carpenter <error27@gmail.com>
> > > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > > Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Switch"")
> > > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > > > ---
> > > >  drivers/net/ethernet/renesas/rswitch.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> > > > index f3d27aef1286..51ce5c26631b 100644
> > > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > > >     }
> > > >
> > > >     for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > > > -           netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > > > +           netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> > >
> > > You can safely drop '\n' from here. It is not needed while printing one
> > > line.
> >
> > Oh, I didn't know that. I'll remove '\n' from here on v2 patch.
> 
> Please don't remove it.  The convention is to have the newlines.

Can you please explain why?

Thanks

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Geert Uytterhoeven]

Hi Leon,

On Thu, Nov 17, 2022 at 10:14 AM Leon Romanovsky <leon@kernel.org> wrote:
> On Thu, Nov 17, 2022 at 09:59:55AM +0100, Geert Uytterhoeven wrote:
> > On Thu, Nov 17, 2022 at 9:58 AM Yoshihiro Shimoda
> > <yoshihiro.shimoda.uh@renesas.com> wrote:
> > > > From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> > > > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > > > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > > > >     }
> > > > >
> > > > >     for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > > > > -           netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > > > > +           netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> > > >
> > > > You can safely drop '\n' from here. It is not needed while printing one
> > > > line.
> > >
> > > Oh, I didn't know that. I'll remove '\n' from here on v2 patch.
> >
> > Please don't remove it.  The convention is to have the newlines.
>
> Can you please explain why?

I'm quite sure this was discussed in the context of commits
5fd29d6ccbc98884 ("printk: clean up handling of log-levels and
newlines") and 4bcc595ccd80decb ("printk: reinstate KERN_CONT for
printing continuation lines"), but I couldn't find a pointer to an
official statement.

I did find[1], which states:

    The printk subsystem will, for every printk, check
    if the last printk has a newline termination and if
    it doesn't and the current printk does not start with
    KERN_CONT will insert a newline.

    The negative to this approach is the last printk,
    if it does not have a newline, is buffered and not
    emitted until another printk occurs.

    There is also the (now small) possibility that
    multiple concurrent kernel threads or processes
    could interleave printks without a terminating
    newline and a different process could emit a
    printk that starts with KERN_CONT and the emitted
    message could be garbled.

[1] https://lore.kernel.org/all/b867ee8a02043ec6b18c9330bfe3a091d66c816c.camel@perches.com

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Leon Romanovsky]

On Thu, Nov 17, 2022 at 10:38:16AM +0100, Geert Uytterhoeven wrote:
> Hi Leon,
> 
> On Thu, Nov 17, 2022 at 10:14 AM Leon Romanovsky <leon@kernel.org> wrote:
> > On Thu, Nov 17, 2022 at 09:59:55AM +0100, Geert Uytterhoeven wrote:
> > > On Thu, Nov 17, 2022 at 9:58 AM Yoshihiro Shimoda
> > > <yoshihiro.shimoda.uh@renesas.com> wrote:
> > > > > From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> > > > > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > > > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > > > > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > > > > >     }
> > > > > >
> > > > > >     for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > > > > > -           netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > > > > > +           netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> > > > >
> > > > > You can safely drop '\n' from here. It is not needed while printing one
> > > > > line.
> > > >
> > > > Oh, I didn't know that. I'll remove '\n' from here on v2 patch.
> > >
> > > Please don't remove it.  The convention is to have the newlines.
> >
> > Can you please explain why?
> 
> I'm quite sure this was discussed in the context of commits
> 5fd29d6ccbc98884 ("printk: clean up handling of log-levels and
> newlines") and 4bcc595ccd80decb ("printk: reinstate KERN_CONT for
> printing continuation lines"), but I couldn't find a pointer to an
> official statement.

Not a printk expert, but in first commit, Linus removed need of "\n"
together with KERN_CONT, and in second commit he returned KERN_CONT,
but didn't return need of "\n".

> 
> I did find[1], which states:
> 
>     The printk subsystem will, for every printk, check
>     if the last printk has a newline termination and if
>     it doesn't and the current printk does not start with
>     KERN_CONT will insert a newline.
> 
>     The negative to this approach is the last printk,
>     if it does not have a newline, is buffered and not
>     emitted until another printk occurs.

I have no idea if it is continue to be true in 2022.

> 
>     There is also the (now small) possibility that
>     multiple concurrent kernel threads or processes
>     could interleave printks without a terminating
>     newline and a different process could emit a
>     printk that starts with KERN_CONT and the emitted
>     message could be garbled.
> 
> [1] https://lore.kernel.org/all/b867ee8a02043ec6b18c9330bfe3a091d66c816c.camel@perches.com
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

RE: [PATCH] net: ethernet: renesas: rswitch: Fix MAC address info

[Yoshihiro Shimoda]

Hi Geert-san,

> From: Geert Uytterhoeven, Sent: Thursday, November 17, 2022 6:38 PM
> 
> Hi Leon,
> 
> On Thu, Nov 17, 2022 at 10:14 AM Leon Romanovsky <leon@kernel.org> wrote:
> > On Thu, Nov 17, 2022 at 09:59:55AM +0100, Geert Uytterhoeven wrote:
> > > On Thu, Nov 17, 2022 at 9:58 AM Yoshihiro Shimoda
> > > <yoshihiro.shimoda.uh@renesas.com> wrote:
> > > > > From: Leon Romanovsky, Sent: Thursday, November 17, 2022 3:09 PM
> > > > > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > > > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > > > > @@ -1714,7 +1714,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > > > > >     }
> > > > > >
> > > > > >     for (i = 0; i < RSWITCH_NUM_PORTS; i++)
> > > > > > -           netdev_info(priv->rdev[i]->ndev, "MAC address %pMn",
> > > > > > +           netdev_info(priv->rdev[i]->ndev, "MAC address %pM\n",
> > > > >
> > > > > You can safely drop '\n' from here. It is not needed while printing one
> > > > > line.
> > > >
> > > > Oh, I didn't know that. I'll remove '\n' from here on v2 patch.
> > >
> > > Please don't remove it.  The convention is to have the newlines.
> >
> > Can you please explain why?
> 
> I'm quite sure this was discussed in the context of commits
> 5fd29d6ccbc98884 ("printk: clean up handling of log-levels and
> newlines") and 4bcc595ccd80decb ("printk: reinstate KERN_CONT for
> printing continuation lines"), but I couldn't find a pointer to an
> official statement.
> 
> I did find[1], which states:
> 
>     The printk subsystem will, for every printk, check
>     if the last printk has a newline termination and if
>     it doesn't and the current printk does not start with
>     KERN_CONT will insert a newline.
> 
>     The negative to this approach is the last printk,
>     if it does not have a newline, is buffered and not
>     emitted until another printk occurs.

Thank you for your reply and sharing information.
I'll keep '\n' on v2 patch.

Best regards,
Yoshihiro Shimoda

>     There is also the (now small) possibility that
>     multiple concurrent kernel threads or processes
>     could interleave printks without a terminating
>     newline and a different process could emit a
>     printk that starts with KERN_CONT and the emitted
>     message could be garbled.
> 
> [1]
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds