diff options
Diffstat (limited to 'drivers/ptp/ptp_private.h')
| -rw-r--r-- | drivers/ptp/ptp_private.h | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h index 528d86a33f37..a6aad743c282 100644 --- a/drivers/ptp/ptp_private.h +++ b/drivers/ptp/ptp_private.h @@ -98,7 +98,27 @@ static inline int queue_cnt(const struct timestamp_event_queue *q) /* Check if ptp virtual clock is in use */ static inline bool ptp_vclock_in_use(struct ptp_clock *ptp) { - return !ptp->is_virtual_clock; + bool in_use = false; + + /* Virtual clocks can't be stacked on top of virtual clocks. + * Avoid acquiring the n_vclocks_mux on virtual clocks, to allow this + * function to be called from code paths where the n_vclocks_mux of the + * parent physical clock is already held. Functionally that's not an + * issue, but lockdep would complain, because they have the same lock + * class. + */ + if (ptp->is_virtual_clock) + return false; + + if (mutex_lock_interruptible(&ptp->n_vclocks_mux)) + return true; + + if (ptp->n_vclocks) + in_use = true; + + mutex_unlock(&ptp->n_vclocks_mux); + + return in_use; } /* Check if ptp clock shall be free running */ |