| Message ID | 20210616091426.13694-2-qiangqing.zhang@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | net: fixes for fec ptp | expand |
On Wed, Jun 16, 2021 at 05:14:25PM +0800, Joakim Zhang wrote: > From: Fugang Duan <fugang.duan@nxp.com> > > Add clock rate zero check to fix coverity issue of "divide by 0". > > Fixes: commit 85bd1798b24a ("net: fec: fix spin_lock dead lock") > Signed-off-by: Fugang Duan <fugang.duan@nxp.com> > Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com> > --- > drivers/net/ethernet/freescale/fec_ptp.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c > index 1753807cbf97..7326a0612823 100644 > --- a/drivers/net/ethernet/freescale/fec_ptp.c > +++ b/drivers/net/ethernet/freescale/fec_ptp.c > @@ -604,6 +604,10 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx) > fep->ptp_caps.enable = fec_ptp_enable; > > fep->cycle_speed = clk_get_rate(fep->clk_ptp); > + if (!fep->cycle_speed) { > + fep->cycle_speed = NSEC_PER_SEC; > + dev_err(&fep->pdev->dev, "clk_ptp clock rate is zero\n"); If this is supposed to be an error message, it doesn't convey that something is really wrong to the user. Maybe something like this would be more meaningful to the user: "PTP clock rate should not be zero, using 1GHz instead. PTP clock may be unreliable.\n" It may be appropriate not to publish PTP support for the interface if we don't have a valid clock rate, which is probably the safer approach and would probably make the problem more noticable to the end user so it gets fixed.
Hi Russell, > -----Original Message----- > From: Russell King <linux@armlinux.org.uk> > Sent: 2021年6月16日 18:21 > To: Joakim Zhang <qiangqing.zhang@nxp.com> > Cc: davem@davemloft.net; kuba@kernel.org; peppe.cavallaro@st.com; > alexandre.torgue@foss.st.com; joabreu@synopsys.com; > mcoquelin.stm32@gmail.com; netdev@vger.kernel.org; > linux-kernel@vger.kernel.org; linux-stm32@st-md-mailman.stormreply.com; > linux-arm-kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com> > Subject: Re: [PATCH net 1/2] net: fec_ptp: add clock rate zero check > > On Wed, Jun 16, 2021 at 05:14:25PM +0800, Joakim Zhang wrote: > > From: Fugang Duan <fugang.duan@nxp.com> > > > > Add clock rate zero check to fix coverity issue of "divide by 0". > > > > Fixes: commit 85bd1798b24a ("net: fec: fix spin_lock dead lock") > > Signed-off-by: Fugang Duan <fugang.duan@nxp.com> > > Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com> > > --- > > drivers/net/ethernet/freescale/fec_ptp.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/net/ethernet/freescale/fec_ptp.c > > b/drivers/net/ethernet/freescale/fec_ptp.c > > index 1753807cbf97..7326a0612823 100644 > > --- a/drivers/net/ethernet/freescale/fec_ptp.c > > +++ b/drivers/net/ethernet/freescale/fec_ptp.c > > @@ -604,6 +604,10 @@ void fec_ptp_init(struct platform_device *pdev, int > irq_idx) > > fep->ptp_caps.enable = fec_ptp_enable; > > > > fep->cycle_speed = clk_get_rate(fep->clk_ptp); > > + if (!fep->cycle_speed) { > > + fep->cycle_speed = NSEC_PER_SEC; > > + dev_err(&fep->pdev->dev, "clk_ptp clock rate is zero\n"); > > If this is supposed to be an error message, it doesn't convey that something is > really wrong to the user. Maybe something like this would be more meaningful > to the user: > > "PTP clock rate should not be zero, using 1GHz instead. PTP > clock may be unreliable.\n" Make Sense. > It may be appropriate not to publish PTP support for the interface if we don't > have a valid clock rate, which is probably the safer approach and would > probably make the problem more noticable to the end user so it gets fixed. Do you mean that print an error message then return directly? It seems better. if (!fep->cycle_speed) { dev_err(&fep->pdev->dev, "PTP clock rate should not be zero!\n"); return; } Best Regards, Joakim Zhang > -- > RMK's Patch system: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ar > mlinux.org.uk%2Fdeveloper%2Fpatches%2F&data=04%7C01%7Cqiangqin > g.zhang%40nxp.com%7Cb3c85322e359446e4eee08d930b06701%7C686ea1d3 > bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637594356476903644%7CUnknow > n%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1ha > WwiLCJXVCI6Mn0%3D%7C1000&sdata=TH4fZJRu8Ii6w7y05N8CHWoQR > R9OegsYB7VAwgSpTcU%3D&reserved=0 > FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
Hi Joakim, On Wed, Jun 16, 2021 at 11:40:29AM +0000, Joakim Zhang wrote: > Do you mean that print an error message then return directly? It seems better. Nearly - one has to ensure that the cleanup functions don't provoke a crash though. I notice fec_ptp_stop() makes use of fep->time_keep and also fep->ptp_clock. fep->time_keep is initialised after where you need to test for zero cycle_speed, so the initialisation would need moving earlier. I would have thought that ftp->ptp_clock should be NULL, so that's probably okay, but should be checked that this assumption is in fact true. > if (!fep->cycle_speed) { > dev_err(&fep->pdev->dev, "PTP clock rate should not be zero!\n"); I'd still say something like "PTP clock rate should not be zero, disabling PTP" - say what's wrong and what we are doing. Also, please avoid exclaimation marks in error messages. Thanks.
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c index 1753807cbf97..7326a0612823 100644 --- a/drivers/net/ethernet/freescale/fec_ptp.c +++ b/drivers/net/ethernet/freescale/fec_ptp.c @@ -604,6 +604,10 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx) fep->ptp_caps.enable = fec_ptp_enable; fep->cycle_speed = clk_get_rate(fep->clk_ptp); + if (!fep->cycle_speed) { + fep->cycle_speed = NSEC_PER_SEC; + dev_err(&fep->pdev->dev, "clk_ptp clock rate is zero\n"); + } fep->ptp_inc = NSEC_PER_SEC / fep->cycle_speed; spin_lock_init(&fep->tmreg_lock);