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Commit 68435b04 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti
Browse files

cpu-hotplug: Keep atleast 1 online and un-isolated CPU 



The PM_QOS_CPU_DMA_LATENCY vote attached to an IRQ is discarded,
if it is affined to an isolated CPU. So we need atleast 1 CPU
in online and un-isolate state. The scheduler rejects isolating
a CPU if it is the only online and un-isolated CPU in the system.
Add the same check for CPU hotplug.

Change-Id: I5bdfe6e3bb0352ed3ae5a2de90097b73d248f3fc
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent a2005826

include/linux/cpumask.h

+8 −0
Original line number Diff line number Diff line
@@ -103,6 +103,13 @@ extern struct cpumask __cpu_isolated_mask; 
#define num_present_cpus()	cpumask_weight(cpu_present_mask)

#define num_active_cpus()	cpumask_weight(cpu_active_mask)

#define num_isolated_cpus()	cpumask_weight(cpu_isolated_mask)

#define num_online_uniso_cpus()						\

({									\

	cpumask_t mask;							\

									\

	cpumask_andnot(&mask, cpu_online_mask, cpu_isolated_mask);	\

	cpumask_weight(&mask);						\

})

#define cpu_online(cpu)		cpumask_test_cpu((cpu), cpu_online_mask)

#define cpu_possible(cpu)	cpumask_test_cpu((cpu), cpu_possible_mask)

#define cpu_present(cpu)	cpumask_test_cpu((cpu), cpu_present_mask)
@@ -114,6 +121,7 @@ extern struct cpumask __cpu_isolated_mask; 
#define num_present_cpus()	1U

#define num_active_cpus()	1U

#define num_isolated_cpus()	0U

#define num_online_uniso_cpus()	1U

#define cpu_online(cpu)		((cpu) == 0)

#define cpu_possible(cpu)	((cpu) == 0)

#define cpu_present(cpu)	((cpu) == 0)

kernel/cpu.c

+3 −0
Original line number Diff line number Diff line
@@ -886,6 +886,9 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, 
	if (!cpu_present(cpu))

		return -EINVAL;



	if (!tasks_frozen && !cpu_isolated(cpu) && num_online_uniso_cpus() == 1)

		return -EBUSY;



	cpu_hotplug_begin();



	cpuhp_tasks_frozen = tasks_frozen;