* [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
@ 2026-01-28 14:27 Andy Shevchenko
2026-01-28 15:09 ` Ilpo Järvinen
0 siblings, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2026-01-28 14:27 UTC (permalink / raw)
To: Greg Kroah-Hartman, Jiri Slaby (SUSE), linux-kernel, linux-serial
Cc: Ilpo Järvinen, Andy Shevchenko
serial8250_release_dma() is NULL-aware, no need to check this in the caller.
While at it, make sure DMA won't be used again, by NULLifying the pointer.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/tty/serial/8250/8250_port.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 21fdf84f118f..c40d750d5a4b 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2366,8 +2366,8 @@ void serial8250_do_shutdown(struct uart_port *port)
synchronize_irq(port->irq);
- if (up->dma)
- serial8250_release_dma(up);
+ serial8250_release_dma(up);
+ up->dma = NULL;
scoped_guard(uart_port_lock_irqsave, port) {
if (port->flags & UPF_FOURPORT) {
--
2.50.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
2026-01-28 14:27 [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check Andy Shevchenko
@ 2026-01-28 15:09 ` Ilpo Järvinen
2026-01-28 15:44 ` Andy Shevchenko
0 siblings, 1 reply; 7+ messages in thread
From: Ilpo Järvinen @ 2026-01-28 15:09 UTC (permalink / raw)
To: Andy Shevchenko; +Cc: Greg Kroah-Hartman, Jiri Slaby (SUSE), LKML, linux-serial
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On Wed, 28 Jan 2026, Andy Shevchenko wrote:
> serial8250_release_dma() is NULL-aware, no need to check this in the caller.
> While at it, make sure DMA won't be used again, by NULLifying the pointer.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/tty/serial/8250/8250_port.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 21fdf84f118f..c40d750d5a4b 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2366,8 +2366,8 @@ void serial8250_do_shutdown(struct uart_port *port)
>
> synchronize_irq(port->irq);
>
> - if (up->dma)
> - serial8250_release_dma(up);
> + serial8250_release_dma(up);
> + up->dma = NULL;
>
> scoped_guard(uart_port_lock_irqsave, port) {
> if (port->flags & UPF_FOURPORT) {
>
Seems reasonable safeguard,
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
--
i.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
2026-01-28 15:09 ` Ilpo Järvinen
@ 2026-01-28 15:44 ` Andy Shevchenko
0 siblings, 0 replies; 7+ messages in thread
From: Andy Shevchenko @ 2026-01-28 15:44 UTC (permalink / raw)
To: Ilpo Järvinen
Cc: Greg Kroah-Hartman, Jiri Slaby (SUSE), LKML, linux-serial
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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On Wed, Jan 28, 2026 at 05:09:31PM +0200, Ilpo Järvinen wrote:
> On Wed, 28 Jan 2026, Andy Shevchenko wrote:
...
> > - if (up->dma)
> > - serial8250_release_dma(up);
> > + serial8250_release_dma(up);
> > + up->dma = NULL;
>
> Seems reasonable safeguard,
Note, 8250_omap does the same for last 3 years.
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Thanks!
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
@ 2026-03-02 15:27 Andy Shevchenko
2026-03-03 5:25 ` Jiri Slaby
0 siblings, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2026-03-02 15:27 UTC (permalink / raw)
To: Greg Kroah-Hartman, Jiri Slaby (SUSE), linux-kernel, linux-serial
Cc: Andy Shevchenko
serial8250_release_dma() is NULL-aware, no need to check this in the caller.
While at it, make sure DMA won't be used again, by NULLifying the pointer.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/tty/serial/8250/8250_port.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index d99c5ad7e47c..2a830969d22b 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2366,8 +2366,8 @@ void serial8250_do_shutdown(struct uart_port *port)
synchronize_irq(port->irq);
- if (up->dma)
- serial8250_release_dma(up);
+ serial8250_release_dma(up);
+ up->dma = NULL;
scoped_guard(uart_port_lock_irqsave, port) {
if (port->flags & UPF_FOURPORT) {
--
2.50.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
2026-03-02 15:27 Andy Shevchenko
@ 2026-03-03 5:25 ` Jiri Slaby
2026-03-03 7:55 ` Andy Shevchenko
0 siblings, 1 reply; 7+ messages in thread
From: Jiri Slaby @ 2026-03-03 5:25 UTC (permalink / raw)
To: Andy Shevchenko, Greg Kroah-Hartman, linux-kernel, linux-serial
On 02. 03. 26, 16:27, Andy Shevchenko wrote:
> serial8250_release_dma() is NULL-aware, no need to check this in the caller.
> While at it, make sure DMA won't be used again, by NULLifying the pointer.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/tty/serial/8250/8250_port.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index d99c5ad7e47c..2a830969d22b 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2366,8 +2366,8 @@ void serial8250_do_shutdown(struct uart_port *port)
>
> synchronize_irq(port->irq);
>
> - if (up->dma)
> - serial8250_release_dma(up);
> + serial8250_release_dma(up);
> + up->dma = NULL;
Shouldn't serial8250_release_dma() NULL it instead, so the callers need
not to bother?
thanks,
--
js
suse labs
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
2026-03-03 5:25 ` Jiri Slaby
@ 2026-03-03 7:55 ` Andy Shevchenko
2026-03-03 8:26 ` Andy Shevchenko
0 siblings, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2026-03-03 7:55 UTC (permalink / raw)
To: Jiri Slaby; +Cc: Greg Kroah-Hartman, linux-kernel, linux-serial
On Tue, Mar 03, 2026 at 06:25:29AM +0100, Jiri Slaby wrote:
> On 02. 03. 26, 16:27, Andy Shevchenko wrote:
> > serial8250_release_dma() is NULL-aware, no need to check this in the caller.
> > While at it, make sure DMA won't be used again, by NULLifying the pointer.
> > synchronize_irq(port->irq);
> > - if (up->dma)
> > - serial8250_release_dma(up);
> > + serial8250_release_dma(up);
> > + up->dma = NULL;
>
> Shouldn't serial8250_release_dma() NULL it instead, so the callers need not
> to bother?
I copied what 8250_omap is doing. But we can do what you suggested I think.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check
2026-03-03 7:55 ` Andy Shevchenko
@ 2026-03-03 8:26 ` Andy Shevchenko
0 siblings, 0 replies; 7+ messages in thread
From: Andy Shevchenko @ 2026-03-03 8:26 UTC (permalink / raw)
To: Jiri Slaby; +Cc: Greg Kroah-Hartman, linux-kernel, linux-serial
On Tue, Mar 03, 2026 at 09:55:45AM +0200, Andy Shevchenko wrote:
> On Tue, Mar 03, 2026 at 06:25:29AM +0100, Jiri Slaby wrote:
> > On 02. 03. 26, 16:27, Andy Shevchenko wrote:
> > > serial8250_release_dma() is NULL-aware, no need to check this in the caller.
> > > While at it, make sure DMA won't be used again, by NULLifying the pointer.
...
> > > - if (up->dma)
> > > - serial8250_release_dma(up);
> > > + serial8250_release_dma(up);
> > > + up->dma = NULL;
> >
> > Shouldn't serial8250_release_dma() NULL it instead, so the callers need not
> > to bother?
>
> I copied what 8250_omap is doing. But we can do what you suggested I think.
I looked at the 8250_dma code and serial8250_release_dma() in particular,
and I think I am not going to change the approach. The 'dma' pointer is
assigned outside of serial8250_request_dma() and NULLifying it in
serial8250_release_dma() will be a layering violation.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2026-03-03 8:26 UTC | newest]
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2026-01-28 14:27 [PATCH v1 1/1] serial: 8250_port: Drop duplicate NULL check Andy Shevchenko
2026-01-28 15:09 ` Ilpo Järvinen
2026-01-28 15:44 ` Andy Shevchenko
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2026-03-02 15:27 Andy Shevchenko
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