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Recently I added an RCU annotation check to rcu_assign_pointer(). All pointers assigned to RCU protected data are to be annotated with __rcu inorder to be able to use rcu_assign_pointer() similar to checks in other RCU APIs. This resulted in a sparse error: kernel//sched/cpufreq.c:41:9: sparse: error: incompatible types in comparison expression (different address spaces) Fix this by annotating cpufreq_update_util_data pointer with __rcu. This will also help sparse catch any future RCU misuage bugs. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ From an RCU perspective. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: keescook@chromium.org Cc: kernel-hardening@lists.openwall.com Cc: kernel-team@android.com Link: https://lkml.kernel.org/r/20190321003426.160260-2-joel@joelfernandes.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
59 lines
2.1 KiB
C
59 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Scheduler code and data structures related to cpufreq.
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*
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* Copyright (C) 2016, Intel Corporation
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* Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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*/
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#include "sched.h"
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DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
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/**
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* cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
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* @cpu: The CPU to set the pointer for.
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* @data: New pointer value.
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* @func: Callback function to set for the CPU.
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*
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* Set and publish the update_util_data pointer for the given CPU.
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*
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* The update_util_data pointer of @cpu is set to @data and the callback
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* function pointer in the target struct update_util_data is set to @func.
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* That function will be called by cpufreq_update_util() from RCU-sched
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* read-side critical sections, so it must not sleep. @data will always be
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* passed to it as the first argument which allows the function to get to the
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* target update_util_data structure and its container.
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*
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* The update_util_data pointer of @cpu must be NULL when this function is
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* called or it will WARN() and return with no effect.
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*/
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void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
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void (*func)(struct update_util_data *data, u64 time,
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unsigned int flags))
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{
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if (WARN_ON(!data || !func))
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return;
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if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
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return;
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data->func = func;
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rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
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}
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EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
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/**
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* cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
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* @cpu: The CPU to clear the pointer for.
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*
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* Clear the update_util_data pointer for the given CPU.
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*
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* Callers must use RCU callbacks to free any memory that might be
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* accessed via the old update_util_data pointer or invoke synchronize_rcu()
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* right after this function to avoid use-after-free.
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*/
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void cpufreq_remove_update_util_hook(int cpu)
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{
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rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
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}
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EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
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