kernel/rcu/tree.c:1272:9: warning: context imbalance in 'rcu_start_future_gp' - different lock contexts for basic block
We can simplify the function by keeping the contexts together and removing redundant checks. Signed-off-by: Pranith Kumar <[email protected]> --- kernel/rcu/tree.c | 65 ++++++++++++++++++++++++++++++------------------------- 1 file changed, 35 insertions(+), 30 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index f1ba773..9ab84d3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1234,49 +1234,54 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp, } /* - * There might be no grace period in progress. If we don't already + * There is be no grace period in progress. If we don't already * hold it, acquire the root rcu_node structure's lock in order to - * start one (if needed). + * start one. */ if (rnp != rnp_root) { raw_spin_lock(&rnp_root->lock); smp_mb__after_unlock_lock(); + /* + * Get a new grace-period number. If there really is no grace + * period in progress, it will be smaller than the one we obtained + * earlier. Adjust callbacks as needed. Note that even no-CBs + */ + c = rcu_cbs_completed(rdp->rsp, rnp_root); + + /* + * If the needed request for the required grace period is already + * recorded, trace and leave. + */ + if (rnp_root->need_future_gp[c & 0x1]) { + trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartedroot")); + raw_spin_unlock(&rnp_root->lock); + goto out; + } + + /* Record the need for the future grace period. */ + rnp_root->need_future_gp[c & 0x1]++; + + /* + * Start a new grace period since it is not started + */ + trace_rcu_future_gp(rnp, rdp, c, TPS("Startedroot")); + ret = rcu_start_gp_advanced(rdp->rsp, rnp_root, rdp); + raw_spin_unlock(&rnp_root->lock); + goto out; } + /* rnp == rnp_root, we already hold the lock */ + trace_rcu_future_gp(rnp, rdp, c, TPS("StartedLeaf")); + ret = rcu_start_gp_advanced(rdp->rsp, rnp, rdp); +out: /* - * Get a new grace-period number. If there really is no grace - * period in progress, it will be smaller than the one we obtained - * earlier. Adjust callbacks as needed. Note that even no-CBs - * CPUs have a ->nxtcompleted[] array, so no no-CBs checks needed. + * Adjust callbacks as needed. Note that even no-CBs CPUs + * have a ->nxtcompleted[] array, so no no-CBs checks needed. */ - c = rcu_cbs_completed(rdp->rsp, rnp_root); for (i = RCU_DONE_TAIL; i < RCU_NEXT_TAIL; i++) if (ULONG_CMP_LT(c, rdp->nxtcompleted[i])) rdp->nxtcompleted[i] = c; - /* - * If the needed for the required grace period is already - * recorded, trace and leave. - */ - if (rnp_root->need_future_gp[c & 0x1]) { - trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartedroot")); - goto unlock_out; - } - - /* Record the need for the future grace period. */ - rnp_root->need_future_gp[c & 0x1]++; - - /* If a grace period is not already in progress, start one. */ - if (rnp_root->gpnum != rnp_root->completed) { - trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleafroot")); - } else { - trace_rcu_future_gp(rnp, rdp, c, TPS("Startedroot")); - ret = rcu_start_gp_advanced(rdp->rsp, rnp_root, rdp); - } -unlock_out: - if (rnp != rnp_root) - raw_spin_unlock(&rnp_root->lock); -out: if (c_out != NULL) *c_out = c; return ret; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
