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Commit d35cf744 authored by Jubin John's avatar Jubin John Committed by Doug Ledford
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IB/hfi1: Serialize hrtimer function calls 



hrtimer functions do not guarantee serialization, so we extend the
cca_timer_lock to cover the hrtimer_forward_now() in the hrtimer
callback handler and the hrtimer_start() in process_becn(). This
prevents races between these 2 functions to update the hrtimer state
leading to problems such as:
kernel BUG at kernel/hrtimer.c:1282!
encountered during validation of the CCA feature.

Reviewed-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarJubin John <jubin.john@intel.com>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
parent 1cbaa670

drivers/staging/rdma/hfi1/init.c

+9 −11
Original line number Diff line number Diff line
@@ -422,9 +422,10 @@ static enum hrtimer_restart cca_timer_fn(struct hrtimer *t) 
	struct cca_timer *cca_timer;

	struct hfi1_pportdata *ppd;

	int sl;

	u16 ccti, ccti_timer, ccti_min;

	u16 ccti_timer, ccti_min;

	struct cc_state *cc_state;

	unsigned long flags;

	enum hrtimer_restart ret = HRTIMER_NORESTART;



	cca_timer = container_of(t, struct cca_timer, hrtimer);

	ppd = cca_timer->ppd;
@@ -450,24 +451,21 @@ static enum hrtimer_restart cca_timer_fn(struct hrtimer *t) 


	spin_lock_irqsave(&ppd->cca_timer_lock, flags);



	ccti = cca_timer->ccti;



	if (ccti > ccti_min) {

	if (cca_timer->ccti > ccti_min) {

		cca_timer->ccti--;

		set_link_ipg(ppd);

	}



	spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);



	rcu_read_unlock();



	if (ccti > ccti_min) {

	if (cca_timer->ccti > ccti_min) {

		unsigned long nsec = 1024 * ccti_timer;

		/* ccti_timer is in units of 1.024 usec */

		hrtimer_forward_now(t, ns_to_ktime(nsec));

		return HRTIMER_RESTART;

		ret = HRTIMER_RESTART;

	}

	return HRTIMER_NORESTART;



	spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);

	rcu_read_unlock();

	return ret;

}



/*

drivers/staging/rdma/hfi1/rc.c

+3 −4
Original line number Diff line number Diff line
@@ -2021,8 +2021,6 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn, 
	if (sl >= OPA_MAX_SLS)

		return;



	cca_timer = &ppd->cca_timer[sl];



	cc_state = get_cc_state(ppd);



	if (!cc_state)
@@ -2041,6 +2039,7 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn, 


	spin_lock_irqsave(&ppd->cca_timer_lock, flags);



	cca_timer = &ppd->cca_timer[sl];

	if (cca_timer->ccti < ccti_limit) {

		if (cca_timer->ccti + ccti_incr <= ccti_limit)

			cca_timer->ccti += ccti_incr;
@@ -2049,8 +2048,6 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn, 
		set_link_ipg(ppd);

	}



	spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);



	ccti = cca_timer->ccti;



	if (!hrtimer_active(&cca_timer->hrtimer)) {
@@ -2061,6 +2058,8 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn, 
			      HRTIMER_MODE_REL);

	}



	spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);



	if ((trigger_threshold != 0) && (ccti >= trigger_threshold))

		log_cca_event(ppd, sl, rlid, lqpn, rqpn, svc_type);

}