ab2af1f500
Patch to eliminate struct files_struct.file_lock spinlock on the reader side and use rcu refcounting rcuref_xxx api for the f_count refcounter. The updates to the fdtable are done by allocating a new fdtable structure and setting files->fdt to point to the new structure. The fdtable structure is protected by RCU thereby allowing lock-free lookup. For fd arrays/sets that are vmalloced, we use keventd to free them since RCU callbacks can't sleep. A global list of fdtable to be freed is not scalable, so we use a per-cpu list. If keventd is already handling the current cpu's work, we use a timer to defer queueing of that work. Since the last publication, this patch has been re-written to avoid using explicit memory barriers and use rcu_assign_pointer(), rcu_dereference() premitives instead. This required that the fd information is kept in a separate structure (fdtable) and updated atomically. Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
136 lines
3.7 KiB
C
136 lines
3.7 KiB
C
#ifndef _LINUX__INIT_TASK_H
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#define _LINUX__INIT_TASK_H
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#include <linux/file.h>
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#include <linux/rcupdate.h>
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#define INIT_FDTABLE \
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{ \
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.max_fds = NR_OPEN_DEFAULT, \
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.max_fdset = __FD_SETSIZE, \
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.next_fd = 0, \
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.fd = &init_files.fd_array[0], \
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.close_on_exec = &init_files.close_on_exec_init, \
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.open_fds = &init_files.open_fds_init, \
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.rcu = RCU_HEAD_INIT, \
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.free_files = NULL, \
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.next = NULL, \
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}
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#define INIT_FILES \
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{ \
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.count = ATOMIC_INIT(1), \
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.file_lock = SPIN_LOCK_UNLOCKED, \
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.fdt = &init_files.fdtab, \
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.fdtab = INIT_FDTABLE, \
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.close_on_exec_init = { { 0, } }, \
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.open_fds_init = { { 0, } }, \
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.fd_array = { NULL, } \
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}
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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, \
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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, \
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.mmlist = LIST_HEAD_INIT(name.mmlist), \
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.cpu_vm_mask = CPU_MASK_ALL, \
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.default_kioctx = INIT_KIOCTX(name.default_kioctx, name), \
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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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}
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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, \
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}
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extern struct group_info init_groups;
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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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.thread_info = &init_thread_info, \
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.usage = ATOMIC_INIT(2), \
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.flags = 0, \
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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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.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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.run_list = LIST_HEAD_INIT(tsk.run_list), \
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.ioprio = 0, \
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.time_slice = HZ, \
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.tasks = LIST_HEAD_INIT(tsk.tasks), \
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.ptrace_children= LIST_HEAD_INIT(tsk.ptrace_children), \
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.ptrace_list = LIST_HEAD_INIT(tsk.ptrace_list), \
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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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.group_info = &init_groups, \
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.cap_effective = CAP_INIT_EFF_SET, \
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.cap_inheritable = CAP_INIT_INH_SET, \
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.cap_permitted = CAP_FULL_SET, \
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.keep_capabilities = 0, \
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.user = INIT_USER, \
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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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.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, \
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.proc_lock = SPIN_LOCK_UNLOCKED, \
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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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}
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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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