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