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Message-ID: <20210619040623.GA14326@localhost>
Date: Sat, 19 Jun 2021 06:06:23 +0200
From: Richard Cochran <richardcochran@...il.com>
To: Yangbo Lu <yangbo.lu@....com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org, mptcp@...ts.linux.dev,
"David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Mat Martineau <mathew.j.martineau@...ux.intel.com>,
Matthieu Baerts <matthieu.baerts@...sares.net>,
Shuah Khan <shuah@...nel.org>,
Michal Kubecek <mkubecek@...e.cz>,
Florian Fainelli <f.fainelli@...il.com>,
Andrew Lunn <andrew@...n.ch>, Rui Sousa <rui.sousa@....com>,
Sebastien Laveze <sebastien.laveze@....com>
Subject: Re: [net-next, v3, 02/10] ptp: support ptp physical/virtual clocks
conversion
On Tue, Jun 15, 2021 at 05:45:09PM +0800, Yangbo Lu wrote:
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index a780435331c8..78414b3e16dd 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -76,6 +76,11 @@ static int ptp_clock_settime(struct posix_clock *pc, const struct timespec64 *tp
> {
> struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
>
> + if (ptp_guaranteed_pclock(ptp)) {
Can we please invent a more descriptive name for this method?
The word "guaranteed" suggests much more.
> + pr_err("ptp: virtual clock in use, guarantee physical clock free running\n");
This is good: ^^^^^^^^^^^^^^^^^^^^^^^^^
You can drop this part: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
So, please rename ptp_guaranteed_pclock() to ptp_vclock_in_use();
> + return -EBUSY;
> + }
> +
> return ptp->info->settime64(ptp->info, tp);
> }
> diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> index 3f388d63904c..6949afc9d733 100644
> --- a/drivers/ptp/ptp_private.h
> +++ b/drivers/ptp/ptp_private.h
> @@ -46,6 +46,9 @@ struct ptp_clock {
> const struct attribute_group *pin_attr_groups[2];
> struct kthread_worker *kworker;
> struct kthread_delayed_work aux_work;
> + u8 n_vclocks;
Why not use "unsigned int" type? I don't see a need to set an artificial limit.
> + struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
> + bool vclock_flag;
"flag" is vague. How about "is_virtual_clock" instead?
> };
>
> #define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
> @@ -75,6 +78,18 @@ static inline int queue_cnt(struct timestamp_event_queue *q)
> return cnt < 0 ? PTP_MAX_TIMESTAMPS + cnt : cnt;
> }
>
> +/*
> + * Guarantee physical clock to stay free running, if ptp virtual clocks
> + * on it are in use.
> + */
> +static inline bool ptp_guaranteed_pclock(struct ptp_clock *ptp)
> +{
> + if (!ptp->vclock_flag && ptp->n_vclocks)
Need to take mutex for n_vclocks to prevent load tearing.
> + return true;
> +
> + return false;
> +}
> +
> /*
> * see ptp_chardev.c
> */
> @@ -148,6 +149,90 @@ static ssize_t pps_enable_store(struct device *dev,
> }
> static DEVICE_ATTR(pps_enable, 0220, NULL, pps_enable_store);
>
> +static int unregister_vclock(struct device *dev, void *data)
> +{
> + struct ptp_clock *ptp = dev_get_drvdata(dev);
> + struct ptp_clock_info *info = ptp->info;
> + struct ptp_vclock *vclock;
> + u8 *num = data;
> +
> + vclock = info_to_vclock(info);
> + dev_info(dev->parent, "delete virtual clock ptp%d\n",
> + vclock->clock->index);
> +
> + ptp_vclock_unregister(vclock);
> + (*num)--;
> +
> + /* For break. Not error. */
> + if (*num == 0)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static ssize_t n_vclocks_show(struct device *dev,
> + struct device_attribute *attr, char *page)
> +{
> + struct ptp_clock *ptp = dev_get_drvdata(dev);
> +
> + return snprintf(page, PAGE_SIZE-1, "%d\n", ptp->n_vclocks);
Take mutex.
> +}
> +
> +static ssize_t n_vclocks_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct ptp_clock *ptp = dev_get_drvdata(dev);
> + struct ptp_vclock *vclock;
> + int err = -EINVAL;
> + u8 num, i;
> +
> + if (kstrtou8(buf, 0, &num))
> + goto out;
> +
> + if (num > PTP_MAX_VCLOCKS) {
> + dev_err(dev, "max value is %d\n", PTP_MAX_VCLOCKS);
> + goto out;
> + }
> +
> + if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
> + return -ERESTARTSYS;
> +
> + /* Need to create more vclocks */
> + if (num > ptp->n_vclocks) {
> + for (i = 0; i < num - ptp->n_vclocks; i++) {
> + vclock = ptp_vclock_register(ptp);
> + if (!vclock) {
> + mutex_unlock(&ptp->n_vclocks_mux);
> + goto out;
> + }
> +
> + dev_info(dev, "new virtual clock ptp%d\n",
> + vclock->clock->index);
> + }
> + }
> +
> + /* Need to delete vclocks */
> + if (num < ptp->n_vclocks) {
> + i = ptp->n_vclocks - num;
> + device_for_each_child_reverse(dev, &i,
> + unregister_vclock);
> + }
> +
> + if (num == 0)
> + dev_info(dev, "only physical clock in use now\n");
> + else
> + dev_info(dev, "guarantee physical clock free running\n");
> +
> + ptp->n_vclocks = num;
> + mutex_unlock(&ptp->n_vclocks_mux);
> +
> + return count;
> +out:
> + return err;
> +}
> +static DEVICE_ATTR_RW(n_vclocks);
> +
> static struct attribute *ptp_attrs[] = {
> &dev_attr_clock_name.attr,
>
> diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h
> index 1d108d597f66..4b933dc1b81b 100644
> --- a/include/uapi/linux/ptp_clock.h
> +++ b/include/uapi/linux/ptp_clock.h
> @@ -69,6 +69,11 @@
> */
> #define PTP_PEROUT_V1_VALID_FLAGS (0)
>
> +/*
> + * Max number of PTP virtual clocks per PTP physical clock
> + */
> +#define PTP_MAX_VCLOCKS 20
Why limit this to twenty clocks?
Thanks,
Richard
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