Commit 40b4d3dc authored by Ricardo Neri's avatar Ricardo Neri Committed by Peter Zijlstra
Browse files

sched/topology: Check SDF_SHARED_CHILD in highest_flag_domain() 



Do not assume that all the children of a scheduling domain have a given
flag. Check whether it has the SDF_SHARED_CHILD meta flag.

Suggested-by: default avatarIonela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: default avatarRicardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230406203148.19182-9-ricardo.neri-calderon@linux.intel.com
parent c9ca0788

kernel/sched/sched.h

+19 −3
Original line number Diff line number Diff line
@@ -1772,6 +1772,13 @@ queue_balance_callback(struct rq *rq, 
	for (__sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd); \

			__sd; __sd = __sd->parent)



/* A mask of all the SD flags that have the SDF_SHARED_CHILD metaflag */

#define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_SHARED_CHILD)) |

static const unsigned int SD_SHARED_CHILD_MASK =

#include <linux/sched/sd_flags.h>

0;

#undef SD_FLAG



/**

 * highest_flag_domain - Return highest sched_domain containing flag.

 * @cpu:	The CPU whose highest level of sched domain is to
@@ -1779,16 +1786,25 @@ queue_balance_callback(struct rq *rq, 
 * @flag:	The flag to check for the highest sched_domain

 *		for the given CPU.

 *

 * Returns the highest sched_domain of a CPU which contains the given flag.

 * Returns the highest sched_domain of a CPU which contains @flag. If @flag has

 * the SDF_SHARED_CHILD metaflag, all the children domains also have @flag.

 */

static inline struct sched_domain *highest_flag_domain(int cpu, int flag)

{

	struct sched_domain *sd, *hsd = NULL;



	for_each_domain(cpu, sd) {

		if (!(sd->flags & flag))

			break;

		if (sd->flags & flag) {

			hsd = sd;

			continue;

		}



		/*

		 * Stop the search if @flag is known to be shared at lower

		 * levels. It will not be found further up.

		 */

		if (flag & SD_SHARED_CHILD_MASK)

			break;

	}



	return hsd;