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| author | Tobias Huschle <huschle@linux.ibm.com> | 2023-08-16 10:28:20 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2023-09-19 14:26:55 +0300 |
| commit | 496bb034f4ff4866452ced7fdfaa4a0736230bdf (patch) | |
| tree | 7f58003791f03b5bcaf6928e73c81f9056f8614b | |
| parent | 4a1725281fc5b0009944b1c0e1d2c1dc311a09ec (diff) | |
| download | linux-496bb034f4ff4866452ced7fdfaa4a0736230bdf.tar.xz | |
s390/smp: disallow CPU hotplug of CPU 0
On s390, CPU 0 has special properties in comparison to other CPUs, as it
cannot be deconfigured for example. Therefore, allowing to hotplug CPU 0
introduces additional complexity when handling these properties.
Disallowing to hotplug CPU 0 allows to remove such complexities.
This follows x86 which also prevents offlining of CPU0 since commit
e59e74dc48a3 ("x86/topology: Remove CPU0 hotplug option").
[hca@linux.ibm.com: changed commit message]
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Tobias Huschle <huschle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/kernel/smp.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index c63be2efd689..e8284cec36e7 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -1076,11 +1076,9 @@ static ssize_t cpu_configure_store(struct device *dev, cpus_read_lock(); mutex_lock(&smp_cpu_state_mutex); rc = -EBUSY; - /* disallow configuration changes of online cpus and cpu 0 */ + /* disallow configuration changes of online cpus */ cpu = dev->id; cpu = smp_get_base_cpu(cpu); - if (cpu == 0) - goto out; for (i = 0; i <= smp_cpu_mtid; i++) if (cpu_online(cpu + i)) goto out; @@ -1180,7 +1178,7 @@ static int smp_add_present_cpu(int cpu) return -ENOMEM; per_cpu(cpu_device, cpu) = c; s = &c->dev; - c->hotpluggable = 1; + c->hotpluggable = !!cpu; rc = register_cpu(c, cpu); if (rc) goto out; |