evie/android_kernel_oneplus_msm8998
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cpu-hotplug: Keep atleast 1 online and un-isolated CPU

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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: Pavankumar Kondeti <pkondeti@codeaurora.org>
This commit is contained in:
Pavankumar Kondeti 2017-06-29 16:17:55 +05:30
parent 84c69cb5aa
commit 76aa496f89
2 changed files with 11 additions and 0 deletions
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8
include/linux/cpumask.h
View file

@ -98,6 +98,13 @@ extern const struct cpumask *const 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)
@ -109,6 +116,7 @@ extern const struct cpumask *const 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)

3
kernel/cpu.c
View file

@ -361,6 +361,9 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
if (!cpu_online(cpu))
return -EINVAL;
if (!tasks_frozen && !cpu_isolated(cpu) && num_online_uniso_cpus() == 1)
return -EBUSY;
cpu_hotplug_begin();
err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);