diff mbox series

[v2,1/1] net: fec: ptp: avoid register access when ipg clock is disabled

Message ID 20210225211514.9115-1-heiko.thiery@gmail.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series [v2,1/1] net: fec: ptp: avoid register access when ipg clock is disabled | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Guessed tree name to be net-next
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Heiko Thiery Feb. 25, 2021, 9:15 p.m. UTC
When accessing the timecounter register on an i.MX8MQ the kernel hangs.
This is only the case when the interface is down. This can be reproduced
by reading with 'phc_ctrl eth0 get'.

Like described in the change in 91c0d987a9788dcc5fe26baafd73bf9242b68900
the igp clock is disabled when the interface is down and leads to a
system hang.

So we check if the ptp clock status before reading the timecounter
register.

Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
---
v2:
 - add mutex (thanks to Richard)

v3:
I did a mistake and did not test properly
 - add parenteses
 - fix the used variable

 drivers/net/ethernet/freescale/fec_ptp.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Heiko Thiery Feb. 26, 2021, 7:22 a.m. UTC | #1
Hi all,

Am Do., 25. Feb. 2021 um 22:15 Uhr schrieb Heiko Thiery
<heiko.thiery@gmail.com>:
>
> When accessing the timecounter register on an i.MX8MQ the kernel hangs.
> This is only the case when the interface is down. This can be reproduced
> by reading with 'phc_ctrl eth0 get'.
>
> Like described in the change in 91c0d987a9788dcc5fe26baafd73bf9242b68900
> the igp clock is disabled when the interface is down and leads to a
> system hang.
>
> So we check if the ptp clock status before reading the timecounter
> register.
>
> Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>


Sorry for the noise. But just realized that I sent a v3 version of the
patch but forgot to update the subject line (still v2). Should I
resend it with the correct subject?

> ---
> v2:
>  - add mutex (thanks to Richard)
>
> v3:
> I did a mistake and did not test properly
>  - add parenteses
>  - fix the used variable
>
>  drivers/net/ethernet/freescale/fec_ptp.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
> index 2e344aada4c6..1753807cbf97 100644
> --- a/drivers/net/ethernet/freescale/fec_ptp.c
> +++ b/drivers/net/ethernet/freescale/fec_ptp.c
> @@ -377,9 +377,16 @@ static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
>         u64 ns;
>         unsigned long flags;
>
> +       mutex_lock(&adapter->ptp_clk_mutex);
> +       /* Check the ptp clock */
> +       if (!adapter->ptp_clk_on) {
> +               mutex_unlock(&adapter->ptp_clk_mutex);
> +               return -EINVAL;
> +       }
>         spin_lock_irqsave(&adapter->tmreg_lock, flags);
>         ns = timecounter_read(&adapter->tc);
>         spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
> +       mutex_unlock(&adapter->ptp_clk_mutex);
>
>         *ts = ns_to_timespec64(ns);
>
> --
> 2.30.0
>
Richard Cochran Feb. 26, 2021, 3:23 p.m. UTC | #2
On Thu, Feb 25, 2021 at 10:15:16PM +0100, Heiko Thiery wrote:
> When accessing the timecounter register on an i.MX8MQ the kernel hangs.
> This is only the case when the interface is down. This can be reproduced
> by reading with 'phc_ctrl eth0 get'.
> 
> Like described in the change in 91c0d987a9788dcc5fe26baafd73bf9242b68900
> the igp clock is disabled when the interface is down and leads to a
> system hang.
> 
> So we check if the ptp clock status before reading the timecounter
> register.
> 
> Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
> ---
> v2:
>  - add mutex (thanks to Richard)
> 
> v3:
> I did a mistake and did not test properly
>  - add parenteses
>  - fix the used variable

Acked-by: Richard Cochran <richardcochran@gmail.com>
Jakub Kicinski Feb. 26, 2021, 11:44 p.m. UTC | #3
On Fri, 26 Feb 2021 07:23:31 -0800 Richard Cochran wrote:
> On Thu, Feb 25, 2021 at 10:15:16PM +0100, Heiko Thiery wrote:
> > When accessing the timecounter register on an i.MX8MQ the kernel hangs.
> > This is only the case when the interface is down. This can be reproduced
> > by reading with 'phc_ctrl eth0 get'.
> > 
> > Like described in the change in 91c0d987a9788dcc5fe26baafd73bf9242b68900
> > the igp clock is disabled when the interface is down and leads to a
> > system hang.
> > 
> > So we check if the ptp clock status before reading the timecounter
> > register.
> > 
> > Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
> > ---
> > v2:
> >  - add mutex (thanks to Richard)
> > 
> > v3:
> > I did a mistake and did not test properly
> >  - add parenteses
> >  - fix the used variable  

On Fri, 26 Feb 2021 08:22:50 +0100 Heiko Thiery wrote:
> Sorry for the noise. But just realized that I sent a v3 version of the
> patch but forgot to update the subject line (still v2). Should I
> resend it with the correct subject?

No need, looks like patchwork caught the right version.

> Acked-by: Richard Cochran <richardcochran@gmail.com>

Applied, thanks!
diff mbox series

Patch

diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index 2e344aada4c6..1753807cbf97 100644
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -377,9 +377,16 @@  static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
 	u64 ns;
 	unsigned long flags;
 
+	mutex_lock(&adapter->ptp_clk_mutex);
+	/* Check the ptp clock */
+	if (!adapter->ptp_clk_on) {
+		mutex_unlock(&adapter->ptp_clk_mutex);
+		return -EINVAL;
+	}
 	spin_lock_irqsave(&adapter->tmreg_lock, flags);
 	ns = timecounter_read(&adapter->tc);
 	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
+	mutex_unlock(&adapter->ptp_clk_mutex);
 
 	*ts = ns_to_timespec64(ns);