[PATCH] tty: serial: ucc_uart: use WARN_ON() instead of BUG()

[PATCH] tty: serial: ucc_uart: use WARN_ON() instead of BUG()

[Akhilesh Patil]

Replace BUG() with WARN_ON() as recommended in
Documentation/process/deprecated.rst
Fix system entering into unstable/break/undebuggable state due to use
of BUG(). Follow strict suggestions as per [1] [2].

Link: https://lore.kernel.org/lkml/CA+55aFy6jNLsywVYdGp83AMrXBo_P-pkjkphPGrO=82SPKCpLQ@mail.gmail.com/ [1]
Link: https://lore.kernel.org/lkml/CAHk-=whDHsbK3HTOpTF=ue_o04onRwTEaK_ZoJp_fjbqq4+=Jw@mail.gmail.com/ [2]
Signed-off-by: Akhilesh Patil <akhilesh@ee.iitb.ac.in>
---
 drivers/tty/serial/ucc_uart.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
index 0613f8c11ab1..6214ab1b67cb 100644
--- a/drivers/tty/serial/ucc_uart.c
+++ b/drivers/tty/serial/ucc_uart.c
@@ -223,7 +223,7 @@ static inline dma_addr_t cpu2qe_addr(void *addr, struct uart_qe_port *qe_port)
 
 	/* something nasty happened */
 	printk(KERN_ERR "%s: addr=%p\n", __func__, addr);
-	BUG();
+	WARN_ON(1);
 	return 0;
 }
 
@@ -242,7 +242,7 @@ static inline void *qe2cpu_addr(dma_addr_t addr, struct uart_qe_port *qe_port)
 
 	/* something nasty happened */
 	printk(KERN_ERR "%s: addr=%llx\n", __func__, (u64)addr);
-	BUG();
+	WARN_ON(1);
 	return NULL;
 }
 
-- 
2.34.1

Re: [PATCH] tty: serial: ucc_uart: use WARN_ON() instead of BUG()

[Greg KH]

On Mon, Jul 28, 2025 at 07:14:25AM +0530, Akhilesh Patil wrote:
> Replace BUG() with WARN_ON() as recommended in
> Documentation/process/deprecated.rst
> Fix system entering into unstable/break/undebuggable state due to use
> of BUG(). Follow strict suggestions as per [1] [2].
> 
> Link: https://lore.kernel.org/lkml/CA+55aFy6jNLsywVYdGp83AMrXBo_P-pkjkphPGrO=82SPKCpLQ@mail.gmail.com/ [1]
> Link: https://lore.kernel.org/lkml/CAHk-=whDHsbK3HTOpTF=ue_o04onRwTEaK_ZoJp_fjbqq4+=Jw@mail.gmail.com/ [2]
> Signed-off-by: Akhilesh Patil <akhilesh@ee.iitb.ac.in>
> ---
>  drivers/tty/serial/ucc_uart.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
> index 0613f8c11ab1..6214ab1b67cb 100644
> --- a/drivers/tty/serial/ucc_uart.c
> +++ b/drivers/tty/serial/ucc_uart.c
> @@ -223,7 +223,7 @@ static inline dma_addr_t cpu2qe_addr(void *addr, struct uart_qe_port *qe_port)
>  
>  	/* something nasty happened */
>  	printk(KERN_ERR "%s: addr=%p\n", __func__, addr);
> -	BUG();
> +	WARN_ON(1);
>  	return 0;
>  }
>  
> @@ -242,7 +242,7 @@ static inline void *qe2cpu_addr(dma_addr_t addr, struct uart_qe_port *qe_port)
>  
>  	/* something nasty happened */
>  	printk(KERN_ERR "%s: addr=%llx\n", __func__, (u64)addr);
> -	BUG();
> +	WARN_ON(1);
>  	return NULL;
>  }

You can't just do a search/replace for these types of things, otherwise
we would have done so a long time ago.

How did you test this patch?  The BUG() here assumes that if this ever
fires, the system is really broken, how have you recovered from that
broken state?

thanks,

greg k-h

Re: [PATCH] tty: serial: ucc_uart: use WARN_ON() instead of BUG()

[Akhilesh Patil]

On Mon, Jul 28, 2025 at 06:07:22AM +0200, Greg KH wrote:
> On Mon, Jul 28, 2025 at 07:14:25AM +0530, Akhilesh Patil wrote:
> > Replace BUG() with WARN_ON() as recommended in
> > Documentation/process/deprecated.rst
> > Fix system entering into unstable/break/undebuggable state due to use
> > of BUG(). Follow strict suggestions as per [1] [2].
> > 
> > Link: https://lore.kernel.org/lkml/CA+55aFy6jNLsywVYdGp83AMrXBo_P-pkjkphPGrO=82SPKCpLQ@mail.gmail.com/ [1]
> > Link: https://lore.kernel.org/lkml/CAHk-=whDHsbK3HTOpTF=ue_o04onRwTEaK_ZoJp_fjbqq4+=Jw@mail.gmail.com/ [2]
> > Signed-off-by: Akhilesh Patil <akhilesh@ee.iitb.ac.in>
> > ---
> >  drivers/tty/serial/ucc_uart.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
> > index 0613f8c11ab1..6214ab1b67cb 100644
> > --- a/drivers/tty/serial/ucc_uart.c
> > +++ b/drivers/tty/serial/ucc_uart.c
> > @@ -223,7 +223,7 @@ static inline dma_addr_t cpu2qe_addr(void *addr, struct uart_qe_port *qe_port)
> >  
> >  	/* something nasty happened */
> >  	printk(KERN_ERR "%s: addr=%p\n", __func__, addr);
> > -	BUG();
> > +	WARN_ON(1);
> >  	return 0;
> >  }
> >  
> > @@ -242,7 +242,7 @@ static inline void *qe2cpu_addr(dma_addr_t addr, struct uart_qe_port *qe_port)
> >  
> >  	/* something nasty happened */
> >  	printk(KERN_ERR "%s: addr=%llx\n", __func__, (u64)addr);
> > -	BUG();
> > +	WARN_ON(1);
> >  	return NULL;
> >  }
> 
> You can't just do a search/replace for these types of things, otherwise
> we would have done so a long time ago.
> 

Hi greg, Agree. Let me dive deep to understand this BUG() -> WARN()
recommendation and come back after detailed analysis for this change.
> How did you test this patch?  The BUG() here assumes that if this ever

I have done only build check with NXP p1025rdb configuration as I do not
have this particular hardware handy.
> fires, the system is really broken, how have you recovered from that
> broken state?
> 
> thanks,
> 
> greg k-h

Thanks for the review :) 

Regards,
Akhilesh