diff options
Diffstat (limited to 'drivers/ptp/ptp_private.h')
| -rw-r--r-- | drivers/ptp/ptp_private.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h index 18934e28469e..a6aad743c282 100644 --- a/drivers/ptp/ptp_private.h +++ b/drivers/ptp/ptp_private.h @@ -100,10 +100,20 @@ static inline bool ptp_vclock_in_use(struct ptp_clock *ptp) { 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->is_virtual_clock && ptp->n_vclocks) + if (ptp->n_vclocks) in_use = true; mutex_unlock(&ptp->n_vclocks_mux); |