261842b7c9
The tracing infrastructure allows for recursion. That is, an interrupt may interrupt the act of tracing an event, and that interrupt may very well perform its own trace. This is a recursive trace, and is fine to do. The problem arises when there is a bug, and the utility doing the trace calls something that recurses back into the tracer. This recursion is not caused by an external event like an interrupt, but by code that is not expected to recurse. The result could be a lockup. This patch adds a bitmask to the task structure that keeps track of the trace recursion. To find the interrupt depth, the following algorithm is used: level = hardirq_count() + softirq_count() + in_nmi; Here, level will be the depth of interrutps and softirqs, and even handles the nmi. Then the corresponding bit is set in the recursion bitmask. If the bit was already set, we know we had a recursion at the same level and we warn about it and fail the writing to the buffer. After the data has been committed to the buffer, we clear the bit. No atomics are needed. The only races are with interrupts and they reset the bitmask before returning anywy. [ Impact: detect same irq level trace recursion ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
202 lines
5.6 KiB
C
202 lines
5.6 KiB
C
#ifndef _LINUX__INIT_TASK_H
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#define _LINUX__INIT_TASK_H
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#include <linux/rcupdate.h>
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#include <linux/irqflags.h>
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#include <linux/utsname.h>
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#include <linux/lockdep.h>
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#include <linux/ftrace.h>
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#include <linux/ipc.h>
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#include <linux/pid_namespace.h>
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#include <linux/user_namespace.h>
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#include <linux/securebits.h>
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#include <net/net_namespace.h>
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extern struct files_struct init_files;
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extern struct fs_struct init_fs;
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#define INIT_KIOCTX(name, which_mm) \
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{ \
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.users = ATOMIC_INIT(1), \
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.dead = 0, \
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.mm = &which_mm, \
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.user_id = 0, \
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.next = NULL, \
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.wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait), \
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.ctx_lock = __SPIN_LOCK_UNLOCKED(name.ctx_lock), \
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.reqs_active = 0U, \
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.max_reqs = ~0U, \
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}
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#define INIT_MM(name) \
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{ \
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.mm_rb = RB_ROOT, \
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.pgd = swapper_pg_dir, \
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.mm_users = ATOMIC_INIT(2), \
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.mm_count = ATOMIC_INIT(1), \
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.mmap_sem = __RWSEM_INITIALIZER(name.mmap_sem), \
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.page_table_lock = __SPIN_LOCK_UNLOCKED(name.page_table_lock), \
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.mmlist = LIST_HEAD_INIT(name.mmlist), \
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.cpu_vm_mask = CPU_MASK_ALL, \
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}
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#define INIT_SIGNALS(sig) { \
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.count = ATOMIC_INIT(1), \
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.wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
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.shared_pending = { \
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.list = LIST_HEAD_INIT(sig.shared_pending.list), \
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.signal = {{0}}}, \
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.posix_timers = LIST_HEAD_INIT(sig.posix_timers), \
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.cpu_timers = INIT_CPU_TIMERS(sig.cpu_timers), \
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.rlim = INIT_RLIMITS, \
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.cputimer = { \
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.cputime = INIT_CPUTIME, \
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.running = 0, \
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.lock = __SPIN_LOCK_UNLOCKED(sig.cputimer.lock), \
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}, \
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}
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extern struct nsproxy init_nsproxy;
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#define INIT_NSPROXY(nsproxy) { \
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.pid_ns = &init_pid_ns, \
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.count = ATOMIC_INIT(1), \
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.uts_ns = &init_uts_ns, \
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.mnt_ns = NULL, \
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INIT_NET_NS(net_ns) \
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INIT_IPC_NS(ipc_ns) \
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}
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#define INIT_SIGHAND(sighand) { \
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.count = ATOMIC_INIT(1), \
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.action = { { { .sa_handler = NULL, } }, }, \
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.siglock = __SPIN_LOCK_UNLOCKED(sighand.siglock), \
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.signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(sighand.signalfd_wqh), \
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}
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extern struct group_info init_groups;
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#define INIT_STRUCT_PID { \
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.count = ATOMIC_INIT(1), \
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.tasks = { \
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{ .first = &init_task.pids[PIDTYPE_PID].node }, \
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{ .first = &init_task.pids[PIDTYPE_PGID].node }, \
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{ .first = &init_task.pids[PIDTYPE_SID].node }, \
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}, \
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.rcu = RCU_HEAD_INIT, \
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.level = 0, \
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.numbers = { { \
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.nr = 0, \
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.ns = &init_pid_ns, \
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.pid_chain = { .next = NULL, .pprev = NULL }, \
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}, } \
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}
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#define INIT_PID_LINK(type) \
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{ \
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.node = { \
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.next = NULL, \
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.pprev = &init_struct_pid.tasks[type].first, \
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}, \
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.pid = &init_struct_pid, \
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}
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#ifdef CONFIG_AUDITSYSCALL
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#define INIT_IDS \
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.loginuid = -1, \
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.sessionid = -1,
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#else
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#define INIT_IDS
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#endif
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#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
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/*
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* Because of the reduced scope of CAP_SETPCAP when filesystem
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* capabilities are in effect, it is safe to allow CAP_SETPCAP to
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* be available in the default configuration.
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*/
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# define CAP_INIT_BSET CAP_FULL_SET
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#else
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# define CAP_INIT_BSET CAP_INIT_EFF_SET
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#endif
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extern struct cred init_cred;
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/*
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* INIT_TASK is used to set up the first task table, touch at
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* your own risk!. Base=0, limit=0x1fffff (=2MB)
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*/
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#define INIT_TASK(tsk) \
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{ \
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.state = 0, \
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.stack = &init_thread_info, \
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.usage = ATOMIC_INIT(2), \
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.flags = PF_KTHREAD, \
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.lock_depth = -1, \
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.prio = MAX_PRIO-20, \
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.static_prio = MAX_PRIO-20, \
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.normal_prio = MAX_PRIO-20, \
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.policy = SCHED_NORMAL, \
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.cpus_allowed = CPU_MASK_ALL, \
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.mm = NULL, \
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.active_mm = &init_mm, \
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.se = { \
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.group_node = LIST_HEAD_INIT(tsk.se.group_node), \
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}, \
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.rt = { \
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.run_list = LIST_HEAD_INIT(tsk.rt.run_list), \
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.time_slice = HZ, \
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.nr_cpus_allowed = NR_CPUS, \
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}, \
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.tasks = LIST_HEAD_INIT(tsk.tasks), \
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.pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO), \
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.ptraced = LIST_HEAD_INIT(tsk.ptraced), \
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.ptrace_entry = LIST_HEAD_INIT(tsk.ptrace_entry), \
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.real_parent = &tsk, \
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.parent = &tsk, \
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.children = LIST_HEAD_INIT(tsk.children), \
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.sibling = LIST_HEAD_INIT(tsk.sibling), \
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.group_leader = &tsk, \
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.real_cred = &init_cred, \
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.cred = &init_cred, \
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.cred_exec_mutex = \
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__MUTEX_INITIALIZER(tsk.cred_exec_mutex), \
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.comm = "swapper", \
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.thread = INIT_THREAD, \
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.fs = &init_fs, \
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.files = &init_files, \
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.signal = &init_signals, \
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.sighand = &init_sighand, \
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.nsproxy = &init_nsproxy, \
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.pending = { \
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.list = LIST_HEAD_INIT(tsk.pending.list), \
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.signal = {{0}}}, \
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.blocked = {{0}}, \
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.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
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.journal_info = NULL, \
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.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
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.fs_excl = ATOMIC_INIT(0), \
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.pi_lock = __SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
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.timer_slack_ns = 50000, /* 50 usec default slack */ \
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.pids = { \
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[PIDTYPE_PID] = INIT_PID_LINK(PIDTYPE_PID), \
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[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \
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[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
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}, \
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.dirties = INIT_PROP_LOCAL_SINGLE(dirties), \
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INIT_IDS \
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INIT_TRACE_IRQFLAGS \
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INIT_LOCKDEP \
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INIT_FTRACE_GRAPH \
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INIT_TRACE_RECURSION \
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}
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#define INIT_CPU_TIMERS(cpu_timers) \
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{ \
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LIST_HEAD_INIT(cpu_timers[0]), \
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LIST_HEAD_INIT(cpu_timers[1]), \
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LIST_HEAD_INIT(cpu_timers[2]), \
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}
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#endif
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