Commit c4110804 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

kyber: avoid q->disk dereferences in trace points 



q->disk becomes invalid after the gendisk is removed.  Work around this
by caching the dev_t for the tracepoints.  The real fix would be to
properly tear down the I/O schedulers with the gendisk, but that is
a much more invasive change.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012093301.GA27795@lst.de


Tested-by: default avatarYi Zhang <yi.zhang@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent aec89dc5

block/kyber-iosched.c

+6 −4
Original line number Diff line number Diff line
@@ -151,6 +151,7 @@ struct kyber_ctx_queue { 


struct kyber_queue_data {

	struct request_queue *q;

	dev_t dev;



	/*

	 * Each scheduling domain has a limited number of in-flight requests
@@ -257,7 +258,7 @@ static int calculate_percentile(struct kyber_queue_data *kqd, 
	}

	memset(buckets, 0, sizeof(kqd->latency_buckets[sched_domain][type]));



	trace_kyber_latency(kqd->q, kyber_domain_names[sched_domain],

	trace_kyber_latency(kqd->dev, kyber_domain_names[sched_domain],

			    kyber_latency_type_names[type], percentile,

			    bucket + 1, 1 << KYBER_LATENCY_SHIFT, samples);
@@ -270,7 +271,7 @@ static void kyber_resize_domain(struct kyber_queue_data *kqd, 
	depth = clamp(depth, 1U, kyber_depth[sched_domain]);

	if (depth != kqd->domain_tokens[sched_domain].sb.depth) {

		sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth);

		trace_kyber_adjust(kqd->q, kyber_domain_names[sched_domain],

		trace_kyber_adjust(kqd->dev, kyber_domain_names[sched_domain],

				   depth);

	}

}
@@ -366,6 +367,7 @@ static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q) 
		goto err;



	kqd->q = q;

	kqd->dev = disk_devt(q->disk);



	kqd->cpu_latency = alloc_percpu_gfp(struct kyber_cpu_latency,

					    GFP_KERNEL | __GFP_ZERO);
@@ -774,7 +776,7 @@ kyber_dispatch_cur_domain(struct kyber_queue_data *kqd, 
			list_del_init(&rq->queuelist);

			return rq;

		} else {

			trace_kyber_throttled(kqd->q,

			trace_kyber_throttled(kqd->dev,

					      kyber_domain_names[khd->cur_domain]);

		}

	} else if (sbitmap_any_bit_set(&khd->kcq_map[khd->cur_domain])) {
@@ -787,7 +789,7 @@ kyber_dispatch_cur_domain(struct kyber_queue_data *kqd, 
			list_del_init(&rq->queuelist);

			return rq;

		} else {

			trace_kyber_throttled(kqd->q,

			trace_kyber_throttled(kqd->dev,

					      kyber_domain_names[khd->cur_domain]);

		}

	}

include/trace/events/kyber.h

+9 −10
Original line number Diff line number Diff line
@@ -13,11 +13,11 @@ 


TRACE_EVENT(kyber_latency,



	TP_PROTO(struct request_queue *q, const char *domain, const char *type,

	TP_PROTO(dev_t dev, const char *domain, const char *type,

		 unsigned int percentile, unsigned int numerator,

		 unsigned int denominator, unsigned int samples),



	TP_ARGS(q, domain, type, percentile, numerator, denominator, samples),

	TP_ARGS(dev, domain, type, percentile, numerator, denominator, samples),



	TP_STRUCT__entry(

		__field(	dev_t,	dev				)
@@ -30,7 +30,7 @@ TRACE_EVENT(kyber_latency, 
	),



	TP_fast_assign(

		__entry->dev		= disk_devt(q->disk);

		__entry->dev		= dev;

		strlcpy(__entry->domain, domain, sizeof(__entry->domain));

		strlcpy(__entry->type, type, sizeof(__entry->type));

		__entry->percentile	= percentile;
@@ -47,10 +47,9 @@ TRACE_EVENT(kyber_latency, 


TRACE_EVENT(kyber_adjust,



	TP_PROTO(struct request_queue *q, const char *domain,

		 unsigned int depth),

	TP_PROTO(dev_t dev, const char *domain, unsigned int depth),



	TP_ARGS(q, domain, depth),

	TP_ARGS(dev, domain, depth),



	TP_STRUCT__entry(

		__field(	dev_t,	dev			)
@@ -59,7 +58,7 @@ TRACE_EVENT(kyber_adjust, 
	),



	TP_fast_assign(

		__entry->dev		= disk_devt(q->disk);

		__entry->dev		= dev;

		strlcpy(__entry->domain, domain, sizeof(__entry->domain));

		__entry->depth		= depth;

	),
@@ -71,9 +70,9 @@ TRACE_EVENT(kyber_adjust, 


TRACE_EVENT(kyber_throttled,



	TP_PROTO(struct request_queue *q, const char *domain),

	TP_PROTO(dev_t dev, const char *domain),



	TP_ARGS(q, domain),

	TP_ARGS(dev, domain),



	TP_STRUCT__entry(

		__field(	dev_t,	dev			)
@@ -81,7 +80,7 @@ TRACE_EVENT(kyber_throttled, 
	),



	TP_fast_assign(

		__entry->dev		= disk_devt(q->disk);

		__entry->dev		= dev;

		strlcpy(__entry->domain, domain, sizeof(__entry->domain));

	),