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Diffstat (limited to 'drivers/ptp/ptp_private.h')
-rw-r--r--drivers/ptp/ptp_private.h12
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);