| Message ID | 20211115143004.32743-1-tudor.ambarus@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tty: serial: atmel: Check return code of dmaengine_submit() | expand |
On Mon, Nov 15, 2021 at 04:30:04PM +0200, Tudor Ambarus wrote: > dma_cookie_t < 0 indicates an error code, check for it. Very odd changelog text, please be more descriptive about what is happening here. > > Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> > --- > drivers/tty/serial/atmel_serial.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > index 2c99a47a2535..376f7a9c2868 100644 > --- a/drivers/tty/serial/atmel_serial.c > +++ b/drivers/tty/serial/atmel_serial.c > @@ -1004,6 +1004,11 @@ static void atmel_tx_dma(struct uart_port *port) > desc->callback = atmel_complete_tx_dma; > desc->callback_param = atmel_port; > atmel_port->cookie_tx = dmaengine_submit(desc); > + if (dma_submit_error(atmel_port->cookie_tx)) { > + dev_err(port->dev, "dma_submit_error %d\n", > + atmel_port->cookie_tx); > + return; What can a user do with this error message? Have you seen this happen in real life? What commit does this "fix"? thanks, greg k-h
On 11/15/21 5:58 PM, Greg KH wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > On Mon, Nov 15, 2021 at 04:30:04PM +0200, Tudor Ambarus wrote: >> dma_cookie_t < 0 indicates an error code, check for it. > > Very odd changelog text, please be more descriptive about what is > happening here. > The tx_submit() method of struct dma_async_tx_descriptor is entitled to do sanity checks and return errors if encountered. It's not the case for the DMA controller drivers that this client is using (at_h/xdmac), because they currently don't do sanity checks and always return a positive cookie at tx_submit() method. In case the controller drivers will implement sanity checks and return errors, print a message so that the client will be informed that something went wrong at tx_submit() level. >> >> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> >> --- >> drivers/tty/serial/atmel_serial.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c >> index 2c99a47a2535..376f7a9c2868 100644 >> --- a/drivers/tty/serial/atmel_serial.c >> +++ b/drivers/tty/serial/atmel_serial.c >> @@ -1004,6 +1004,11 @@ static void atmel_tx_dma(struct uart_port *port) >> desc->callback = atmel_complete_tx_dma; >> desc->callback_param = atmel_port; >> atmel_port->cookie_tx = dmaengine_submit(desc); >> + if (dma_submit_error(atmel_port->cookie_tx)) { >> + dev_err(port->dev, "dma_submit_error %d\n", >> + atmel_port->cookie_tx); >> + return; > > What can a user do with this error message? > will be informed that something went wrong at tx_submit() level. > Have you seen this happen in real life? No. I debugged a locking problem and I observed that dma_submit_error() is not called, so I thought to update this. > > What commit does this "fix"? This is rather an improvement, but if you're looking for a fixes tag, I think we can use: Fixes: 08f738be88bb ("serial: at91: add tx dma support") I'll send a v2 as part of a bigger series. If you find this patch does not worth it, I can as well drop it. Cheers, ta
On Tue, Nov 16, 2021 at 06:14:23AM +0000, Tudor.Ambarus@microchip.com wrote: > On 11/15/21 5:58 PM, Greg KH wrote: > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > On Mon, Nov 15, 2021 at 04:30:04PM +0200, Tudor Ambarus wrote: > >> dma_cookie_t < 0 indicates an error code, check for it. > > > > Very odd changelog text, please be more descriptive about what is > > happening here. > > > > The tx_submit() method of struct dma_async_tx_descriptor is entitled to do > sanity checks and return errors if encountered. It's not the case for the > DMA controller drivers that this client is using (at_h/xdmac), because they > currently don't do sanity checks and always return a positive cookie at > tx_submit() method. In case the controller drivers will implement sanity > checks and return errors, print a message so that the client will be informed > that something went wrong at tx_submit() level. > > >> > >> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> > >> --- > >> drivers/tty/serial/atmel_serial.c | 10 ++++++++++ > >> 1 file changed, 10 insertions(+) > >> > >> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > >> index 2c99a47a2535..376f7a9c2868 100644 > >> --- a/drivers/tty/serial/atmel_serial.c > >> +++ b/drivers/tty/serial/atmel_serial.c > >> @@ -1004,6 +1004,11 @@ static void atmel_tx_dma(struct uart_port *port) > >> desc->callback = atmel_complete_tx_dma; > >> desc->callback_param = atmel_port; > >> atmel_port->cookie_tx = dmaengine_submit(desc); > >> + if (dma_submit_error(atmel_port->cookie_tx)) { > >> + dev_err(port->dev, "dma_submit_error %d\n", > >> + atmel_port->cookie_tx); > >> + return; > > > > What can a user do with this error message? > > > will be informed that something went wrong at tx_submit() level. > > > Have you seen this happen in real life? > > No. I debugged a locking problem and I observed that dma_submit_error() is not called, > so I thought to update this. > > > > > What commit does this "fix"? > > This is rather an improvement, but if you're looking for a fixes tag, I think > we can use: > Fixes: 08f738be88bb ("serial: at91: add tx dma support") > > I'll send a v2 as part of a bigger series. If you find this patch does not worth it, > I can as well drop it. Please resend it because as-is, I can not take it. thanks, greg k-h
On 11/16/21 10:26 AM, Greg KH wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > On Tue, Nov 16, 2021 at 06:14:23AM +0000, Tudor.Ambarus@microchip.com wrote: >> On 11/15/21 5:58 PM, Greg KH wrote: >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >>> >>> On Mon, Nov 15, 2021 at 04:30:04PM +0200, Tudor Ambarus wrote: >>>> dma_cookie_t < 0 indicates an error code, check for it. >>> >>> Very odd changelog text, please be more descriptive about what is >>> happening here. >>> >> >> The tx_submit() method of struct dma_async_tx_descriptor is entitled to do >> sanity checks and return errors if encountered. It's not the case for the >> DMA controller drivers that this client is using (at_h/xdmac), because they >> currently don't do sanity checks and always return a positive cookie at >> tx_submit() method. In case the controller drivers will implement sanity >> checks and return errors, print a message so that the client will be informed >> that something went wrong at tx_submit() level. >> >>>> >>>> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> >>>> --- >>>> drivers/tty/serial/atmel_serial.c | 10 ++++++++++ >>>> 1 file changed, 10 insertions(+) >>>> >>>> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c >>>> index 2c99a47a2535..376f7a9c2868 100644 >>>> --- a/drivers/tty/serial/atmel_serial.c >>>> +++ b/drivers/tty/serial/atmel_serial.c >>>> @@ -1004,6 +1004,11 @@ static void atmel_tx_dma(struct uart_port *port) >>>> desc->callback = atmel_complete_tx_dma; >>>> desc->callback_param = atmel_port; >>>> atmel_port->cookie_tx = dmaengine_submit(desc); >>>> + if (dma_submit_error(atmel_port->cookie_tx)) { >>>> + dev_err(port->dev, "dma_submit_error %d\n", >>>> + atmel_port->cookie_tx); >>>> + return; >>> >>> What can a user do with this error message? >>> >> will be informed that something went wrong at tx_submit() level. >> >>> Have you seen this happen in real life? >> >> No. I debugged a locking problem and I observed that dma_submit_error() is not called, >> so I thought to update this. >> >>> >>> What commit does this "fix"? >> >> This is rather an improvement, but if you're looking for a fixes tag, I think >> we can use: >> Fixes: 08f738be88bb ("serial: at91: add tx dma support") >> >> I'll send a v2 as part of a bigger series. If you find this patch does not worth it, >> I can as well drop it. > > Please resend it because as-is, I can not take it. > I've sent a v2 of this patch as a part of a larger series: https://lore.kernel.org/all/20211116112036.96349-1-tudor.ambarus@microchip.com/ The slave DMA usage was wrong in both the DMA controller driver and the serial driver and patch 1/13 and 3/13 are trying to address that. v2 of this patch is 2/13. I guess all should be considered for an immutable branch on the DMA tree. Cheers, ta
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 2c99a47a2535..376f7a9c2868 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1004,6 +1004,11 @@ static void atmel_tx_dma(struct uart_port *port) desc->callback = atmel_complete_tx_dma; desc->callback_param = atmel_port; atmel_port->cookie_tx = dmaengine_submit(desc); + if (dma_submit_error(atmel_port->cookie_tx)) { + dev_err(port->dev, "dma_submit_error %d\n", + atmel_port->cookie_tx); + return; + } } if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) @@ -1258,6 +1263,11 @@ static int atmel_prepare_rx_dma(struct uart_port *port) desc->callback_param = port; atmel_port->desc_rx = desc; atmel_port->cookie_rx = dmaengine_submit(desc); + if (dma_submit_error(atmel_port->cookie_rx)) { + dev_err(port->dev, "dma_submit_error %d\n", + atmel_port->cookie_rx); + goto chan_err; + } return 0;
dma_cookie_t < 0 indicates an error code, check for it. Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> --- drivers/tty/serial/atmel_serial.c | 10 ++++++++++ 1 file changed, 10 insertions(+)