From b73de91d6a4c97ed586b2a5a6ce7c6fe395d9a3b Mon Sep 17 00:00:00 2001 From: Joel Fernandes Date: Sun, 20 May 2018 21:42:18 -0700 Subject: rcu: Rename the grace-period-request variables and parameters The name 'c' is used for variables and parameters holding the requested grace-period sequence number. However it is no longer very meaningful given the conversions from ->gpnum and (especially) ->completed to ->gp_seq. This commit therefore renames 'c' to 'gp_seq_req'. Previous patch discussion is at: https://patchwork.kernel.org/patch/10396579/ Signed-off-by: Joel Fernandes Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 46 +++++++++++++++++++++++++++------------------- 1 file changed, 27 insertions(+), 19 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 161e8fb8b83f..8c31b1740afc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1546,13 +1546,18 @@ void rcu_cpu_stall_reset(void) /* Trace-event wrapper function for trace_rcu_future_grace_period. */ static void trace_rcu_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, - unsigned long c, const char *s) + unsigned long gp_seq_req, const char *s) { - trace_rcu_future_grace_period(rdp->rsp->name, rnp->gp_seq, c, + trace_rcu_future_grace_period(rdp->rsp->name, rnp->gp_seq, gp_seq_req, rnp->level, rnp->grplo, rnp->grphi, s); } /* + * rcu_start_this_gp - Request the start of a particular grace period + * @rnp: The leaf node of the CPU from which to start. + * @rdp: The rcu_data corresponding to the CPU from which to start. + * @gp_seq_req: The gp_seq of the grace period to start. + * * Start the specified grace period, as needed to handle newly arrived * callbacks. The required future grace periods are recorded in each * rcu_node structure's ->gp_seq_needed field. Returns true if there @@ -1560,9 +1565,11 @@ static void trace_rcu_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, * * The caller must hold the specified rcu_node structure's ->lock, which * is why the caller is responsible for waking the grace-period kthread. + * + * Returns true if the GP thread needs to be awakened else false. */ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, - unsigned long c) + unsigned long gp_seq_req) { bool ret = false; struct rcu_state *rsp = rdp->rsp; @@ -1578,25 +1585,27 @@ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, * not be released. */ raw_lockdep_assert_held_rcu_node(rnp); - trace_rcu_this_gp(rnp, rdp, c, TPS("Startleaf")); + trace_rcu_this_gp(rnp, rdp, gp_seq_req, TPS("Startleaf")); for (rnp_root = rnp; 1; rnp_root = rnp_root->parent) { if (rnp_root != rnp) raw_spin_lock_rcu_node(rnp_root); - if (ULONG_CMP_GE(rnp_root->gp_seq_needed, c) || - rcu_seq_started(&rnp_root->gp_seq, c) || + if (ULONG_CMP_GE(rnp_root->gp_seq_needed, gp_seq_req) || + rcu_seq_started(&rnp_root->gp_seq, gp_seq_req) || (rnp != rnp_root && rcu_seq_state(rcu_seq_current(&rnp_root->gp_seq)))) { - trace_rcu_this_gp(rnp_root, rdp, c, TPS("Prestarted")); + trace_rcu_this_gp(rnp_root, rdp, gp_seq_req, + TPS("Prestarted")); goto unlock_out; } - rnp_root->gp_seq_needed = c; + rnp_root->gp_seq_needed = gp_seq_req; if (rcu_seq_state(rcu_seq_current(&rnp->gp_seq))) { /* * We just marked the leaf, and a grace period * is in progress, which means that rcu_gp_cleanup() * will see the marking. Bail to reduce contention. */ - trace_rcu_this_gp(rnp, rdp, c, TPS("Startedleaf")); + trace_rcu_this_gp(rnp, rdp, gp_seq_req, + TPS("Startedleaf")); goto unlock_out; } if (rnp_root != rnp && rnp_root->parent != NULL) @@ -1607,21 +1616,21 @@ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, /* If GP already in progress, just leave, otherwise start one. */ if (rcu_gp_in_progress(rsp)) { - trace_rcu_this_gp(rnp_root, rdp, c, TPS("Startedleafroot")); + trace_rcu_this_gp(rnp_root, rdp, gp_seq_req, TPS("Startedleafroot")); goto unlock_out; } - trace_rcu_this_gp(rnp_root, rdp, c, TPS("Startedroot")); + trace_rcu_this_gp(rnp_root, rdp, gp_seq_req, TPS("Startedroot")); WRITE_ONCE(rsp->gp_flags, rsp->gp_flags | RCU_GP_FLAG_INIT); rsp->gp_req_activity = jiffies; if (!rsp->gp_kthread) { - trace_rcu_this_gp(rnp_root, rdp, c, TPS("NoGPkthread")); + trace_rcu_this_gp(rnp_root, rdp, gp_seq_req, TPS("NoGPkthread")); goto unlock_out; } trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq), TPS("newreq")); ret = true; /* Caller must wake GP kthread. */ unlock_out: /* Push furthest requested GP to leaf node and rcu_data structure. */ - if (ULONG_CMP_LT(c, rnp_root->gp_seq_needed)) { + if (ULONG_CMP_LT(gp_seq_req, rnp_root->gp_seq_needed)) { rnp->gp_seq_needed = rnp_root->gp_seq_needed; rdp->gp_seq_needed = rnp_root->gp_seq_needed; } @@ -1636,14 +1645,13 @@ unlock_out: */ static bool rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) { - unsigned long c = rnp->gp_seq; bool needmore; struct rcu_data *rdp = this_cpu_ptr(rsp->rda); needmore = ULONG_CMP_LT(rnp->gp_seq, rnp->gp_seq_needed); if (!needmore) rnp->gp_seq_needed = rnp->gp_seq; /* Avoid counter wrap. */ - trace_rcu_this_gp(rnp, rdp, c, + trace_rcu_this_gp(rnp, rdp, rnp->gp_seq, needmore ? TPS("CleanupMore") : TPS("Cleanup")); return needmore; } @@ -1679,7 +1687,7 @@ static void rcu_gp_kthread_wake(struct rcu_state *rsp) static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) { - unsigned long c; + unsigned long gp_seq_req; bool ret = false; raw_lockdep_assert_held_rcu_node(rnp); @@ -1698,9 +1706,9 @@ static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, * accelerating callback invocation to an earlier grace-period * number. */ - c = rcu_seq_snap(&rsp->gp_seq); - if (rcu_segcblist_accelerate(&rdp->cblist, c)) - ret = rcu_start_this_gp(rnp, rdp, c); + gp_seq_req = rcu_seq_snap(&rsp->gp_seq); + if (rcu_segcblist_accelerate(&rdp->cblist, gp_seq_req)) + ret = rcu_start_this_gp(rnp, rdp, gp_seq_req); /* Trace depending on how much we were able to accelerate. */ if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) -- cgit v1.2.3-59-g8ed1b