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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 - Cambridge Greys Ltd
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Derived (i.e. mostly copied) from arch/i386/kernel/irq.c:
  *  Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
  */
 
 #include <linux/cpumask.h>
 #include <linux/hardirq.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <as-layout.h>
 #include <kern_util.h>
 #include <os.h>
 #include <irq_user.h>
 #include <irq_kern.h>
 #include <linux/time-internal.h>
 
 
 extern void free_irqs(void);
 
 /* When epoll triggers we do not know why it did so
  * we can also have different IRQs for read and write.
  * This is why we keep a small irq_reg array for each fd -
  * one entry per IRQ type
  */
 struct irq_reg {
     void *id;
     int irq;
     /* it's cheaper to store this than to query it */
     int events;
     bool active;
     bool pending;
     bool wakeup;
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
     bool pending_on_resume;
     void (*timetravel_handler)(int, int, void *,
                    struct time_travel_event *);
     struct time_travel_event event;
 #endif
 };
 
 struct irq_entry {
     struct list_head list;
     int fd;
     struct irq_reg reg[NUM_IRQ_TYPES];
     bool suspended;
     bool sigio_workaround;
 };
 
 static DEFINE_SPINLOCK(irq_lock);
 static LIST_HEAD(active_fds);
 static DECLARE_BITMAP(irqs_allocated, UM_LAST_SIGNAL_IRQ);
 static bool irqs_suspended;
 
 static void irq_io_loop(struct irq_reg *irq, struct uml_pt_regs *regs)
 {
 /*
  * irq->active guards against reentry
  * irq->pending accumulates pending requests
  * if pending is raised the irq_handler is re-run
  * until pending is cleared
  */
     if (irq->active) {
         irq->active = false;
 
         do {
             irq->pending = false;
             do_IRQ(irq->irq, regs);
         } while (irq->pending);
 
         irq->active = true;
     } else {
         irq->pending = true;
     }
 }
 
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 static void irq_event_handler(struct time_travel_event *ev)
 {
     struct irq_reg *reg = container_of(ev, struct irq_reg, event);
 
     /* do nothing if suspended - just to cause a wakeup */
     if (irqs_suspended)
         return;
 
     generic_handle_irq(reg->irq);
 }
 
 static bool irq_do_timetravel_handler(struct irq_entry *entry,
                       enum um_irq_type t)
 {
     struct irq_reg *reg = &entry->reg[t];
 
     if (!reg->timetravel_handler)
         return false;
 
     /*
      * Handle all messages - we might get multiple even while
      * interrupts are already suspended, due to suspend order
      * etc. Note that time_travel_add_irq_event() will not add
      * an event twice, if it's pending already "first wins".
      */
     reg->timetravel_handler(reg->irq, entry->fd, reg->id, &reg->event);
 
     if (!reg->event.pending)
         return false;
 
     if (irqs_suspended)
         reg->pending_on_resume = true;
     return true;
 }
 #else
 static bool irq_do_timetravel_handler(struct irq_entry *entry,
                       enum um_irq_type t)
 {
     return false;
 }
 #endif
 
 static void sigio_reg_handler(int idx, struct irq_entry *entry, enum um_irq_type t,
                   struct uml_pt_regs *regs,
                   bool timetravel_handlers_only)
 {
     struct irq_reg *reg = &entry->reg[t];
 
     if (!reg->events)
         return;
 
     if (os_epoll_triggered(idx, reg->events) <= 0)
         return;
 
     if (irq_do_timetravel_handler(entry, t))
         return;
 
     /*
      * If we're called to only run time-travel handlers then don't
      * actually proceed but mark sigio as pending (if applicable).
      * For suspend/resume, timetravel_handlers_only may be true
      * despite time-travel not being configured and used.
      */
     if (timetravel_handlers_only) {
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
         mark_sigio_pending();
 #endif
         return;
     }
 
     irq_io_loop(reg, regs);
 }
 
 static void _sigio_handler(struct uml_pt_regs *regs,
                bool timetravel_handlers_only)
 {
     struct irq_entry *irq_entry;
     int n, i;
 
     if (timetravel_handlers_only && !um_irq_timetravel_handler_used())
         return;
 
     while (1) {
         /* This is now lockless - epoll keeps back-referencesto the irqs
          * which have trigger it so there is no need to walk the irq
          * list and lock it every time. We avoid locking by turning off
          * IO for a specific fd by executing os_del_epoll_fd(fd) before
          * we do any changes to the actual data structures
          */
         n = os_waiting_for_events_epoll();
 
         if (n <= 0) {
             if (n == -EINTR)
                 continue;
             else
                 break;
         }
 
         for (i = 0; i < n ; i++) {
             enum um_irq_type t;
 
             irq_entry = os_epoll_get_data_pointer(i);
 
             for (t = 0; t < NUM_IRQ_TYPES; t++)
                 sigio_reg_handler(i, irq_entry, t, regs,
                           timetravel_handlers_only);
         }
     }
 
     if (!timetravel_handlers_only)
         free_irqs();
 }
 
 void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
     _sigio_handler(regs, irqs_suspended);
 }
 
 static struct irq_entry *get_irq_entry_by_fd(int fd)
 {
     struct irq_entry *walk;
 
     lockdep_assert_held(&irq_lock);
 
     list_for_each_entry(walk, &active_fds, list) {
         if (walk->fd == fd)
             return walk;
     }
 
     return NULL;
 }
 
 static void free_irq_entry(struct irq_entry *to_free, bool remove)
 {
     if (!to_free)
         return;
 
     if (remove)
         os_del_epoll_fd(to_free->fd);
     list_del(&to_free->list);
     kfree(to_free);
 }
 
 static bool update_irq_entry(struct irq_entry *entry)
 {
     enum um_irq_type i;
     int events = 0;
 
     for (i = 0; i < NUM_IRQ_TYPES; i++)
         events |= entry->reg[i].events;
 
     if (events) {
         /* will modify (instead of add) if needed */
         os_add_epoll_fd(events, entry->fd, entry);
         return true;
     }
 
     os_del_epoll_fd(entry->fd);
     return false;
 }
 
 static void update_or_free_irq_entry(struct irq_entry *entry)
 {
     if (!update_irq_entry(entry))
         free_irq_entry(entry, false);
 }
 
 static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
                void (*timetravel_handler)(int, int, void *,
                           struct time_travel_event *))
 {
     struct irq_entry *irq_entry;
     int err, events = os_event_mask(type);
     unsigned long flags;
 
     err = os_set_fd_async(fd);
     if (err < 0)
         goto out;
 
     spin_lock_irqsave(&irq_lock, flags);
     irq_entry = get_irq_entry_by_fd(fd);
     if (irq_entry) {
         /* cannot register the same FD twice with the same type */
         if (WARN_ON(irq_entry->reg[type].events)) {
             err = -EALREADY;
             goto out_unlock;
         }
 
         /* temporarily disable to avoid IRQ-side locking */
         os_del_epoll_fd(fd);
     } else {
         irq_entry = kzalloc(sizeof(*irq_entry), GFP_ATOMIC);
         if (!irq_entry) {
             err = -ENOMEM;
             goto out_unlock;
         }
         irq_entry->fd = fd;
         list_add_tail(&irq_entry->list, &active_fds);
         maybe_sigio_broken(fd);
     }
 
     irq_entry->reg[type].id = dev_id;
     irq_entry->reg[type].irq = irq;
     irq_entry->reg[type].active = true;
     irq_entry->reg[type].events = events;
 
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
     if (um_irq_timetravel_handler_used()) {
         irq_entry->reg[type].timetravel_handler = timetravel_handler;
         irq_entry->reg[type].event.fn = irq_event_handler;
     }
 #endif
 
     WARN_ON(!update_irq_entry(irq_entry));
     spin_unlock_irqrestore(&irq_lock, flags);
 
     return 0;
 out_unlock:
     spin_unlock_irqrestore(&irq_lock, flags);
 out:
     return err;
 }
 
 /*
  * Remove the entry or entries for a specific FD, if you
  * don't want to remove all the possible entries then use
  * um_free_irq() or deactivate_fd() instead.
  */
 void free_irq_by_fd(int fd)
 {
     struct irq_entry *to_free;
     unsigned long flags;
 
     spin_lock_irqsave(&irq_lock, flags);
     to_free = get_irq_entry_by_fd(fd);
     free_irq_entry(to_free, true);
     spin_unlock_irqrestore(&irq_lock, flags);
 }
 EXPORT_SYMBOL(free_irq_by_fd);
 
 static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
 {
     struct irq_entry *entry;
     unsigned long flags;
 
     spin_lock_irqsave(&irq_lock, flags);
     list_for_each_entry(entry, &active_fds, list) {
         enum um_irq_type i;
 
         for (i = 0; i < NUM_IRQ_TYPES; i++) {
             struct irq_reg *reg = &entry->reg[i];
 
             if (!reg->events)
                 continue;
             if (reg->irq != irq)
                 continue;
             if (reg->id != dev)
                 continue;
 
             os_del_epoll_fd(entry->fd);
             reg->events = 0;
             update_or_free_irq_entry(entry);
             goto out;
         }
     }
 out:
     spin_unlock_irqrestore(&irq_lock, flags);
 }
 
 void deactivate_fd(int fd, int irqnum)
 {
     struct irq_entry *entry;
     unsigned long flags;
     enum um_irq_type i;
 
     os_del_epoll_fd(fd);
 
     spin_lock_irqsave(&irq_lock, flags);
     entry = get_irq_entry_by_fd(fd);
     if (!entry)
         goto out;
 
     for (i = 0; i < NUM_IRQ_TYPES; i++) {
         if (!entry->reg[i].events)
             continue;
         if (entry->reg[i].irq == irqnum)
             entry->reg[i].events = 0;
     }
 
     update_or_free_irq_entry(entry);
 out:
     spin_unlock_irqrestore(&irq_lock, flags);
 
     ignore_sigio_fd(fd);
 }
 EXPORT_SYMBOL(deactivate_fd);
 
 /*
  * Called just before shutdown in order to provide a clean exec
  * environment in case the system is rebooting.  No locking because
  * that would cause a pointless shutdown hang if something hadn't
  * released the lock.
  */
 int deactivate_all_fds(void)
 {
     struct irq_entry *entry;
 
     /* Stop IO. The IRQ loop has no lock so this is our
      * only way of making sure we are safe to dispose
      * of all IRQ handlers
      */
     os_set_ioignore();
 
     /* we can no longer call kfree() here so just deactivate */
     list_for_each_entry(entry, &active_fds, list)
         os_del_epoll_fd(entry->fd);
     os_close_epoll_fd();
     return 0;
 }
 
 /*
  * do_IRQ handles all normal device IRQs (the special
  * SMP cross-CPU interrupts have their own specific
  * handlers).
  */
 unsigned int do_IRQ(int irq, struct uml_pt_regs *regs)
 {
     struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs);
     irq_enter();
     generic_handle_irq(irq);
     irq_exit();
     set_irq_regs(old_regs);
     return 1;
 }
 
 void um_free_irq(int irq, void *dev)
 {
     if (WARN(irq < 0 || irq > UM_LAST_SIGNAL_IRQ,
          "freeing invalid irq %d", irq))
         return;
 
     free_irq_by_irq_and_dev(irq, dev);
     free_irq(irq, dev);
     clear_bit(irq, irqs_allocated);
 }
 EXPORT_SYMBOL(um_free_irq);
 
 static int
 _um_request_irq(int irq, int fd, enum um_irq_type type,
         irq_handler_t handler, unsigned long irqflags,
         const char *devname, void *dev_id,
         void (*timetravel_handler)(int, int, void *,
                        struct time_travel_event *))
 {
     int err;
 
     if (irq == UM_IRQ_ALLOC) {
         int i;
 
         for (i = UM_FIRST_DYN_IRQ; i < NR_IRQS; i++) {
             if (!test_and_set_bit(i, irqs_allocated)) {
                 irq = i;
                 break;
             }
         }
     }
 
     if (irq < 0)
         return -ENOSPC;
 
     if (fd != -1) {
         err = activate_fd(irq, fd, type, dev_id, timetravel_handler);
         if (err)
             goto error;
     }
 
     err = request_irq(irq, handler, irqflags, devname, dev_id);
     if (err < 0)
         goto error;
 
     return irq;
 error:
     clear_bit(irq, irqs_allocated);
     return err;
 }
 
 int um_request_irq(int irq, int fd, enum um_irq_type type,
            irq_handler_t handler, unsigned long irqflags,
            const char *devname, void *dev_id)
 {
     return _um_request_irq(irq, fd, type, handler, irqflags,
                    devname, dev_id, NULL);
 }
 EXPORT_SYMBOL(um_request_irq);
 
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 int um_request_irq_tt(int irq, int fd, enum um_irq_type type,
               irq_handler_t handler, unsigned long irqflags,
               const char *devname, void *dev_id,
               void (*timetravel_handler)(int, int, void *,
                          struct time_travel_event *))
 {
     return _um_request_irq(irq, fd, type, handler, irqflags,
                    devname, dev_id, timetravel_handler);
 }
 EXPORT_SYMBOL(um_request_irq_tt);
 
 void sigio_run_timetravel_handlers(void)
 {
     _sigio_handler(NULL, true);
 }
 #endif
 
 #ifdef CONFIG_PM_SLEEP
 void um_irqs_suspend(void)
 {
     struct irq_entry *entry;
     unsigned long flags;
 
     irqs_suspended = true;
 
     spin_lock_irqsave(&irq_lock, flags);
     list_for_each_entry(entry, &active_fds, list) {
         enum um_irq_type t;
         bool clear = true;
 
         for (t = 0; t < NUM_IRQ_TYPES; t++) {
             if (!entry->reg[t].events)
                 continue;
 
             /*
              * For the SIGIO_WRITE_IRQ, which is used to handle the
              * SIGIO workaround thread, we need special handling:
              * enable wake for it itself, but below we tell it about
              * any FDs that should be suspended.
              */
             if (entry->reg[t].wakeup ||
                 entry->reg[t].irq == SIGIO_WRITE_IRQ
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
                 || entry->reg[t].timetravel_handler
 #endif
                 ) {
                 clear = false;
                 break;
             }
         }
 
         if (clear) {
             entry->suspended = true;
             os_clear_fd_async(entry->fd);
             entry->sigio_workaround =
                 !__ignore_sigio_fd(entry->fd);
         }
     }
     spin_unlock_irqrestore(&irq_lock, flags);
 }
 
 void um_irqs_resume(void)
 {
     struct irq_entry *entry;
     unsigned long flags;
 
 
     local_irq_save(flags);
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
     /*
      * We don't need to lock anything here since we're in resume
      * and nothing else is running, but have disabled IRQs so we
      * don't try anything else with the interrupt list from there.
      */
     list_for_each_entry(entry, &active_fds, list) {
         enum um_irq_type t;
 
         for (t = 0; t < NUM_IRQ_TYPES; t++) {
             struct irq_reg *reg = &entry->reg[t];
 
             if (reg->pending_on_resume) {
                 irq_enter();
                 generic_handle_irq(reg->irq);
                 irq_exit();
                 reg->pending_on_resume = false;
             }
         }
     }
 #endif
 
     spin_lock(&irq_lock);
     list_for_each_entry(entry, &active_fds, list) {
         if (entry->suspended) {
             int err = os_set_fd_async(entry->fd);
 
             WARN(err < 0, "os_set_fd_async returned %d\n", err);
             entry->suspended = false;
 
             if (entry->sigio_workaround) {
                 err = __add_sigio_fd(entry->fd);
                 WARN(err < 0, "add_sigio_returned %d\n", err);
             }
         }
     }
     spin_unlock_irqrestore(&irq_lock, flags);
 
     irqs_suspended = false;
     send_sigio_to_self();
 }
 
 static int normal_irq_set_wake(struct irq_data *d, unsigned int on)
 {
     struct irq_entry *entry;
     unsigned long flags;
 
     spin_lock_irqsave(&irq_lock, flags);
     list_for_each_entry(entry, &active_fds, list) {
         enum um_irq_type t;
 
         for (t = 0; t < NUM_IRQ_TYPES; t++) {
             if (!entry->reg[t].events)
                 continue;
 
             if (entry->reg[t].irq != d->irq)
                 continue;
             entry->reg[t].wakeup = on;
             goto unlock;
         }
     }
 unlock:
     spin_unlock_irqrestore(&irq_lock, flags);
     return 0;
 }
 #else
 #define normal_irq_set_wake NULL
 #endif
 
 /*
  * irq_chip must define at least enable/disable and ack when
  * the edge handler is used.
  */
 static void dummy(struct irq_data *d)
 {
 }
 
 /* This is used for everything other than the timer. */
 static struct irq_chip normal_irq_type = {
     .name = "SIGIO",
     .irq_disable = dummy,
     .irq_enable = dummy,
     .irq_ack = dummy,
     .irq_mask = dummy,
     .irq_unmask = dummy,
     .irq_set_wake = normal_irq_set_wake,
 };
 
 static struct irq_chip alarm_irq_type = {
     .name = "SIGALRM",
     .irq_disable = dummy,
     .irq_enable = dummy,
     .irq_ack = dummy,
     .irq_mask = dummy,
     .irq_unmask = dummy,
 };
 
 void __init init_IRQ(void)
 {
     int i;
 
     irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_edge_irq);
 
     for (i = 1; i < UM_LAST_SIGNAL_IRQ; i++)
         irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
     /* Initialize EPOLL Loop */
     os_setup_epoll();
 }
 
 /*
  * IRQ stack entry and exit:
  *
  * Unlike i386, UML doesn't receive IRQs on the normal kernel stack
  * and switch over to the IRQ stack after some preparation.  We use
  * sigaltstack to receive signals on a separate stack from the start.
  * These two functions make sure the rest of the kernel won't be too
  * upset by being on a different stack.  The IRQ stack has a
  * thread_info structure at the bottom so that current et al continue
  * to work.
  *
  * to_irq_stack copies the current task's thread_info to the IRQ stack
  * thread_info and sets the tasks's stack to point to the IRQ stack.
  *
  * from_irq_stack copies the thread_info struct back (flags may have
  * been modified) and resets the task's stack pointer.
  *
  * Tricky bits -
  *
  * What happens when two signals race each other?  UML doesn't block
  * signals with sigprocmask, SA_DEFER, or sa_mask, so a second signal
  * could arrive while a previous one is still setting up the
  * thread_info.
  *
  * There are three cases -
  *     The first interrupt on the stack - sets up the thread_info and
  * handles the interrupt
  *     A nested interrupt interrupting the copying of the thread_info -
  * can't handle the interrupt, as the stack is in an unknown state
  *     A nested interrupt not interrupting the copying of the
  * thread_info - doesn't do any setup, just handles the interrupt
  *
  * The first job is to figure out whether we interrupted stack setup.
  * This is done by xchging the signal mask with thread_info->pending.
  * If the value that comes back is zero, then there is no setup in
  * progress, and the interrupt can be handled.  If the value is
  * non-zero, then there is stack setup in progress.  In order to have
  * the interrupt handled, we leave our signal in the mask, and it will
  * be handled by the upper handler after it has set up the stack.
  *
  * Next is to figure out whether we are the outer handler or a nested
  * one.  As part of setting up the stack, thread_info->real_thread is
  * set to non-NULL (and is reset to NULL on exit).  This is the
  * nesting indicator.  If it is non-NULL, then the stack is already
  * set up and the handler can run.
  */
 
 static unsigned long pending_mask;
 
 unsigned long to_irq_stack(unsigned long *mask_out)
 {
     struct thread_info *ti;
     unsigned long mask, old;
     int nested;
 
     mask = xchg(&pending_mask, *mask_out);
     if (mask != 0) {
         /*
          * If any interrupts come in at this point, we want to
          * make sure that their bits aren't lost by our
          * putting our bit in.  So, this loop accumulates bits
          * until xchg returns the same value that we put in.
          * When that happens, there were no new interrupts,
          * and pending_mask contains a bit for each interrupt
          * that came in.
          */
         old = *mask_out;
         do {
             old |= mask;
             mask = xchg(&pending_mask, old);
         } while (mask != old);
         return 1;
     }
 
     ti = current_thread_info();
     nested = (ti->real_thread != NULL);
     if (!nested) {
         struct task_struct *task;
         struct thread_info *tti;
 
         task = cpu_tasks[ti->cpu].task;
         tti = task_thread_info(task);
 
         *ti = *tti;
         ti->real_thread = tti;
         task->stack = ti;
     }
 
     mask = xchg(&pending_mask, 0);
     *mask_out |= mask | nested;
     return 0;
 }
 
 unsigned long from_irq_stack(int nested)
 {
     struct thread_info *ti, *to;
     unsigned long mask;
 
     ti = current_thread_info();
 
     pending_mask = 1;
 
     to = ti->real_thread;
     current->stack = to;
     ti->real_thread = NULL;
     *to = *ti;
 
     mask = xchg(&pending_mask, 0);
     return mask & ~1;
 }
 

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