cpu/hotplug: Get rid of CPU hotplug notifier leftovers
The CPU hotplug notifiers are history. Remove the last reminders. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -6,41 +6,11 @@ specified notifier chain callbacks. It is useful to test the error handling of
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notifier call chain failures which is rarely executed. There are kernel
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modules that can be used to test the following notifiers.
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* CPU notifier
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* PM notifier
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* Memory hotplug notifier
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* powerpc pSeries reconfig notifier
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* Netdevice notifier
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CPU notifier error injection module
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-----------------------------------
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This feature can be used to test the error handling of the CPU notifiers by
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injecting artificial errors to CPU notifier chain callbacks.
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If the notifier call chain should be failed with some events notified, write
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the error code to debugfs interface
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/sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error
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Possible CPU notifier events to be failed are:
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* CPU_UP_PREPARE
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* CPU_UP_PREPARE_FROZEN
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* CPU_DOWN_PREPARE
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* CPU_DOWN_PREPARE_FROZEN
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Example1: Inject CPU offline error (-1 == -EPERM)
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# cd /sys/kernel/debug/notifier-error-inject/cpu
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# echo -1 > actions/CPU_DOWN_PREPARE/error
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# echo 0 > /sys/devices/system/cpu/cpu1/online
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bash: echo: write error: Operation not permitted
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Example2: inject CPU online error (-2 == -ENOENT)
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# echo -2 > actions/CPU_UP_PREPARE/error
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# echo 1 > /sys/devices/system/cpu/cpu1/online
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bash: echo: write error: No such file or directory
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PM notifier error injection module
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----------------------------------
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This feature is controlled through debugfs interface
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@ -232,7 +232,7 @@ d. Handling microcode update during suspend/hibernate:
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hibernate/restore cycle.]
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In the current design of the kernel however, during a CPU offline operation
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as part of the suspend/hibernate cycle (the CPU_DEAD_FROZEN notification),
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as part of the suspend/hibernate cycle (cpuhp_tasks_frozen is set),
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the existing copy of microcode image in the kernel is not freed up.
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And during the CPU online operations (during resume/restore), since the
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kernel finds that it already has copies of the microcode images for all the
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@ -252,10 +252,9 @@ Yes, they are listed below:
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the _cpu_down() and _cpu_up() functions is *always* 0.
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This might not reflect the true current state of the system, since the
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tasks could have been frozen by an out-of-band event such as a suspend
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operation in progress. Hence, it will lead to wrong notifications being
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sent during the cpu online/offline events (eg, CPU_ONLINE notification
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instead of CPU_ONLINE_FROZEN) which in turn will lead to execution of
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inappropriate code by the callbacks registered for such CPU hotplug events.
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operation in progress. Hence, the cpuhp_tasks_frozen variable will not
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reflect the frozen state and the CPU hotplug callbacks which evaluate
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that variable might execute the wrong code path.
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2. If a regular CPU hotplug stress test happens to race with the freezer due
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to a suspend operation in progress at the same time, then we could hit the
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@ -55,24 +55,17 @@ extern void unregister_cpu(struct cpu *cpu);
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extern ssize_t arch_cpu_probe(const char *, size_t);
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extern ssize_t arch_cpu_release(const char *, size_t);
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#endif
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struct notifier_block;
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#define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */
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#define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */
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#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
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#define CPU_POST_DEAD 0x0009 /* CPU (unsigned)v dead, cpu_hotplug
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* lock is dropped */
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#define CPU_BROKEN 0x000B /* CPU (unsigned)v did not die properly,
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* perhaps due to preemption. */
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/* Used for CPU hotplug events occurring while tasks are frozen due to a suspend
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* operation in progress
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/*
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* These states are not related to the core CPU hotplug mechanism. They are
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* used by various (sub)architectures to track internal state
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*/
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#define CPU_TASKS_FROZEN 0x0010
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#define CPU_ONLINE_FROZEN (CPU_ONLINE | CPU_TASKS_FROZEN)
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#define CPU_UP_PREPARE_FROZEN (CPU_UP_PREPARE | CPU_TASKS_FROZEN)
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#define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
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#define CPU_ONLINE 0x0002 /* CPU is up */
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#define CPU_UP_PREPARE 0x0003 /* CPU coming up */
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#define CPU_DEAD 0x0007 /* CPU dead */
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#define CPU_DEAD_FROZEN 0x0008 /* CPU timed out on unplug */
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#define CPU_POST_DEAD 0x0009 /* CPU successfully unplugged */
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#define CPU_BROKEN 0x000B /* CPU did not die properly */
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#ifdef CONFIG_SMP
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extern bool cpuhp_tasks_frozen;
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