diff mbox series

[net,v2,2/5] renesas: reject PTP_STRICT_FLAGS as unsupported

Message ID 20250312-jk-net-fixes-supported-extts-flags-v2-2-ea930ba82459@intel.com (mailing list archive)
State Accepted
Delegated to: Geert Uytterhoeven
Headers show
Series net: ptp: fix egregious supported flag checks | expand

Commit Message

Jacob Keller March 12, 2025, 10:15 p.m. UTC
The ravb_ptp_extts() function checks the flags coming from the
PTP_EXTTS_REQUEST ioctl, to ensure that future flags are not accepted on
accident.

This was updated to 'honor' the PTP_STRICT_FLAGS in commit 6138e687c7b6
("ptp: Introduce strict checking of external time stamp options.").
However, the driver does not *actually* validate the flags.

I originally fixed this driver to reject future flags in commit
592025a03b34 ("renesas: reject unsupported external timestamp flags"). It
is still unclear whether this hardware timestamps the rising, falling, or
both edges of the input signal.

Accepting requests with PTP_STRICT_FLAGS is a bug, as this could lead to
users mistakenly assuming a request with PTP_RISING_EDGE actually
timestamps the rising edge only.

Reject requests with PTP_STRICT_FLAGS (and hence all PTP_EXTTS_REQUEST2
requests) until someone with access to the datasheet or hardware knowledge
can confirm the timestamping behavior and update this driver.

Fixes: 6138e687c7b6 ("ptp: Introduce strict checking of external time stamp options.")
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
 drivers/net/ethernet/renesas/ravb_ptp.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Niklas Söderlund March 13, 2025, 9:45 a.m. UTC | #1
Hi Jacob,

Thanks for your work.

On 2025-03-12 15:15:51 -0700, Jacob Keller wrote:
> The ravb_ptp_extts() function checks the flags coming from the
> PTP_EXTTS_REQUEST ioctl, to ensure that future flags are not accepted on
> accident.
> 
> This was updated to 'honor' the PTP_STRICT_FLAGS in commit 6138e687c7b6
> ("ptp: Introduce strict checking of external time stamp options.").
> However, the driver does not *actually* validate the flags.
> 
> I originally fixed this driver to reject future flags in commit
> 592025a03b34 ("renesas: reject unsupported external timestamp flags"). It
> is still unclear whether this hardware timestamps the rising, falling, or
> both edges of the input signal.
> 
> Accepting requests with PTP_STRICT_FLAGS is a bug, as this could lead to
> users mistakenly assuming a request with PTP_RISING_EDGE actually
> timestamps the rising edge only.
> 
> Reject requests with PTP_STRICT_FLAGS (and hence all PTP_EXTTS_REQUEST2
> requests) until someone with access to the datasheet or hardware knowledge
> can confirm the timestamping behavior and update this driver.
> 
> Fixes: 6138e687c7b6 ("ptp: Introduce strict checking of external time stamp options.")
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/net/ethernet/renesas/ravb_ptp.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
> index 6e4ef7af27bf31ab2aad8e06a65e0ede6046e3c0..b4365906669f3bd40953813e263aeaafd2e1eb70 100644
> --- a/drivers/net/ethernet/renesas/ravb_ptp.c
> +++ b/drivers/net/ethernet/renesas/ravb_ptp.c
> @@ -179,8 +179,7 @@ static int ravb_ptp_extts(struct ptp_clock_info *ptp,
>  	/* Reject requests with unsupported flags */
>  	if (req->flags & ~(PTP_ENABLE_FEATURE |
>  			   PTP_RISING_EDGE |
> -			   PTP_FALLING_EDGE |
> -			   PTP_STRICT_FLAGS))
> +			   PTP_FALLING_EDGE))
>  		return -EOPNOTSUPP;
>  
>  	if (req->index)
> 
> -- 
> 2.48.1.397.gec9d649cc640
>
Simon Horman March 18, 2025, 2:07 p.m. UTC | #2
On Wed, Mar 12, 2025 at 03:15:51PM -0700, Jacob Keller wrote:
> The ravb_ptp_extts() function checks the flags coming from the
> PTP_EXTTS_REQUEST ioctl, to ensure that future flags are not accepted on
> accident.
> 
> This was updated to 'honor' the PTP_STRICT_FLAGS in commit 6138e687c7b6
> ("ptp: Introduce strict checking of external time stamp options.").
> However, the driver does not *actually* validate the flags.
> 
> I originally fixed this driver to reject future flags in commit
> 592025a03b34 ("renesas: reject unsupported external timestamp flags"). It
> is still unclear whether this hardware timestamps the rising, falling, or
> both edges of the input signal.
> 
> Accepting requests with PTP_STRICT_FLAGS is a bug, as this could lead to
> users mistakenly assuming a request with PTP_RISING_EDGE actually
> timestamps the rising edge only.
> 
> Reject requests with PTP_STRICT_FLAGS (and hence all PTP_EXTTS_REQUEST2
> requests) until someone with access to the datasheet or hardware knowledge
> can confirm the timestamping behavior and update this driver.
> 
> Fixes: 6138e687c7b6 ("ptp: Introduce strict checking of external time stamp options.")
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>
diff mbox series

Patch

diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
index 6e4ef7af27bf31ab2aad8e06a65e0ede6046e3c0..b4365906669f3bd40953813e263aeaafd2e1eb70 100644
--- a/drivers/net/ethernet/renesas/ravb_ptp.c
+++ b/drivers/net/ethernet/renesas/ravb_ptp.c
@@ -179,8 +179,7 @@  static int ravb_ptp_extts(struct ptp_clock_info *ptp,
 	/* Reject requests with unsupported flags */
 	if (req->flags & ~(PTP_ENABLE_FEATURE |
 			   PTP_RISING_EDGE |
-			   PTP_FALLING_EDGE |
-			   PTP_STRICT_FLAGS))
+			   PTP_FALLING_EDGE))
 		return -EOPNOTSUPP;
 
 	if (req->index)