Commit b73de91d authored by Joel Fernandes's avatar Joel Fernandes Committed by Paul E. McKenney
Browse files

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: default avatarJoel Fernandes <joel@joelfernandes.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 3d18469a

include/trace/events/rcu.h

+8 −7
Original line number Diff line number Diff line
@@ -103,15 +103,16 @@ TRACE_EVENT(rcu_grace_period, 
 */

TRACE_EVENT(rcu_future_grace_period,



	TP_PROTO(const char *rcuname, unsigned long gp_seq, unsigned long c,

		 u8 level, int grplo, int grphi, const char *gpevent),

	TP_PROTO(const char *rcuname, unsigned long gp_seq,

		 unsigned long gp_seq_req, u8 level, int grplo, int grphi,

		 const char *gpevent),



	TP_ARGS(rcuname, gp_seq, c, level, grplo, grphi, gpevent),

	TP_ARGS(rcuname, gp_seq, gp_seq_req, level, grplo, grphi, gpevent),



	TP_STRUCT__entry(

		__field(const char *, rcuname)

		__field(unsigned long, gp_seq)

		__field(unsigned long, c)

		__field(unsigned long, gp_seq_req)

		__field(u8, level)

		__field(int, grplo)

		__field(int, grphi)
@@ -121,7 +122,7 @@ TRACE_EVENT(rcu_future_grace_period, 
	TP_fast_assign(

		__entry->rcuname = rcuname;

		__entry->gp_seq = gp_seq;

		__entry->c = c;

		__entry->gp_seq_req = gp_seq_req;

		__entry->level = level;

		__entry->grplo = grplo;

		__entry->grphi = grphi;
@@ -129,7 +130,7 @@ TRACE_EVENT(rcu_future_grace_period, 
	),



	TP_printk("%s %lu %lu %u %d %d %s",

		  __entry->rcuname, __entry->gp_seq, __entry->c, __entry->level,

		  __entry->rcuname, __entry->gp_seq, __entry->gp_seq_req, __entry->level,

		  __entry->grplo, __entry->grphi, __entry->gpevent)

);
@@ -751,7 +752,7 @@ TRACE_EVENT(rcu_barrier, 
#else /* #ifdef CONFIG_RCU_TRACE */



#define trace_rcu_grace_period(rcuname, gp_seq, gpevent) do { } while (0)

#define trace_rcu_future_grace_period(rcuname, gp_seq, c, \

#define trace_rcu_future_grace_period(rcuname, gp_seq, gp_seq_req, \

				      level, grplo, grphi, event) \

				      do { } while (0)

#define trace_rcu_grace_period_init(rcuname, gp_seq, level, grplo, grphi, \

kernel/rcu/tree.c

+27 −19
Original line number Diff line number Diff line
@@ -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))

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