mirror of
https://github.com/varun-r-mallya/sysprof.git
synced 2025-12-31 20:36:25 +00:00
Initial revision
This commit is contained in:
Søren Sandmann Pedersen
286
sysprof-module.c
Normal file
286
sysprof-module.c
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#include <linux/config.h>
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#ifdef CONFIG_SMP
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# define __SMP__
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#endif
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#include <asm/atomic.h>
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#include <linux/kernel.h> /* Needed for KERN_ALERT */
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#include <linux/module.h> /* Needed by all modules */
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#include <linux/tqueue.h>
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#include <linux/sched.h>
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#include <linux/proc_fs.h>
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#include <asm/uaccess.h>
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#include <linux/poll.h>
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#include "sysprof-module.h"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Soeren Sandmann (sandmann@daimi.au.dk)");
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#define SAMPLES_PER_SECOND 50 /* must divide HZ */
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static const int cpu_profiler = 0; /* 0: page faults, 1: cpu */
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static void on_timer_interrupt (void *);
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static struct tq_struct timer_task =
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{
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{ NULL, NULL },
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0,
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on_timer_interrupt,
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NULL
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};
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int exiting = 0;
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DECLARE_WAIT_QUEUE_HEAD (wait_for_exit);
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#define N_TRACES 256
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static SysprofStackTrace stack_traces[N_TRACES];
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static SysprofStackTrace * head = &stack_traces[0];
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static SysprofStackTrace * tail = &stack_traces[0];
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DECLARE_WAIT_QUEUE_HEAD (wait_for_trace);
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static void
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generate_stack_trace (struct task_struct *task,
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SysprofStackTrace *trace)
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{
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#define START_OF_STACK 0xBFFFFFFF
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typedef struct StackFrame StackFrame;
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struct StackFrame {
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StackFrame *next;
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void *return_address;
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};
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struct pt_regs *regs = (struct pt_regs *)(
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(long)current + THREAD_SIZE - sizeof (struct pt_regs));
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StackFrame *frame;
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int i;
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memset (trace, 0, sizeof (SysprofStackTrace));
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trace->pid = current->pid;
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trace->truncated = 0;
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trace->addresses[0] = (void *)regs->eip;
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i = 1;
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frame = (StackFrame *)regs->ebp;
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while (frame && i < SYSPROF_MAX_ADDRESSES &&
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(long)frame < (long)START_OF_STACK &&
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(long)frame >= regs->esp)
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{
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void *next = NULL;
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if (verify_area(VERIFY_READ, frame, sizeof(StackFrame)) == 0)
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{
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void *return_address;
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__get_user (return_address, &(frame->return_address));
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__get_user (next, &(frame->next));
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trace->addresses[i++] = return_address;
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if ((long)next <= (long)frame)
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next = NULL;
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}
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frame = next;
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}
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trace->n_addresses = i;
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if (i == SYSPROF_MAX_ADDRESSES)
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trace->truncated = 1;
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else
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trace->truncated = 0;
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}
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struct page *
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hijacked_nopage (struct vm_area_struct * area,
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unsigned long address,
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int unused)
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{
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if (current && current->pid != 0)
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{
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#if 0
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generate_stack_trace (current, head);
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if (head++ == &stack_traces[N_TRACES - 1])
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head = &stack_traces[0];
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wake_up (&wait_for_trace);
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#endif
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memset (head, 0, sizeof (SysprofStackTrace));
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head->n_addresses = 1;
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head->pid = current->pid;
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head->addresses[0] = (void *)address;
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head->truncated = 0;
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if (area->vm_file)
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{
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char *line = d_path (area->vm_file->f_dentry,
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area->vm_file->f_vfsmnt,
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head->filename, PAGE_SIZE);
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strncpy (head->filename, line, sizeof (head->filename) - 1);
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#if 0
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if (line == head->filename)
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printk (KERN_ALERT "got name\n");
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else if (line == NULL)
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printk (KERN_ALERT "noasdf\n");
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else
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printk (KERN_ALERT "%s\n", line);
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#endif
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head->map_start = area->vm_start;
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}
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if (head++ == &stack_traces[N_TRACES - 1])
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head = &stack_traces[0];
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wake_up (&wait_for_trace);
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}
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return filemap_nopage (area, address, unused);
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}
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static void
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hijack_nopages (struct task_struct *task)
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{
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struct mm_struct *mm = task->mm;
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struct vm_area_struct *vma;
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if (!mm)
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return;
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for (vma = mm->mmap; vma != NULL; vma = vma->vm_next)
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{
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if (vma->vm_ops && vma->vm_ops->nopage == filemap_nopage)
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vma->vm_ops->nopage = hijacked_nopage;
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}
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}
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static void
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clean_hijacked_nopages (void)
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{
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struct task_struct *task;
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for_each_process (task)
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{
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struct mm_struct *mm = task->mm;
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if (mm)
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{
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struct vm_area_struct *vma;
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for (vma = mm->mmap; vma != NULL; vma = vma->vm_next)
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{
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if (vma->vm_ops && vma->vm_ops->nopage == hijacked_nopage)
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vma->vm_ops->nopage = filemap_nopage;
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}
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}
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}
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}
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static void
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on_timer_interrupt (void *data)
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{
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static int n_ticks = 0;
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if (exiting)
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{
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clean_hijacked_nopages ();
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wake_up (&wait_for_exit);
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return;
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}
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++n_ticks;
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if (current && current->pid != 0 &&
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(n_ticks % (HZ / SAMPLES_PER_SECOND)) == 0)
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{
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if (cpu_profiler)
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{
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generate_stack_trace (current, head);
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if (head++ == &stack_traces[N_TRACES - 1])
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head = &stack_traces[0];
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wake_up (&wait_for_trace);
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}
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else
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{
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hijack_nopages (current);
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}
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}
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queue_task (&timer_task, &tq_timer);
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}
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static int
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procfile_read (char *buffer,
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char **buffer_location,
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off_t offset,
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int buffer_length,
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int *eof,
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void *data)
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{
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#if 0
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if (offset > 0)
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return 0;
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#endif
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wait_event_interruptible (wait_for_trace, head != tail);
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*buffer_location = (char *)tail;
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if (tail++ == &stack_traces[N_TRACES - 1])
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tail = &stack_traces[0];
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return sizeof (SysprofStackTrace);
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}
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struct proc_dir_entry *trace_proc_file;
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static unsigned int
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procfile_poll (struct file *filp, poll_table *poll_table)
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{
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if (head != tail)
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{
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return POLLIN;
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}
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poll_wait (filp, &wait_for_trace, poll_table);
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if (head != tail)
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{
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return POLLIN;
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}
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return 0;
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}
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int
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init_module (void)
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{
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trace_proc_file =
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create_proc_entry ("sysprof-trace", S_IFREG | S_IRUGO, &proc_root);
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if (!trace_proc_file)
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return 1;
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trace_proc_file->read_proc = procfile_read;
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trace_proc_file->proc_fops->poll = procfile_poll;
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trace_proc_file->size = sizeof (SysprofStackTrace);
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queue_task(&timer_task, &tq_timer);
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printk (KERN_ALERT "starting sysprof module\n");
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return 0;
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}
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void
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cleanup_module(void)
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{
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exiting = 1;
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sleep_on (&wait_for_exit);
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remove_proc_entry ("sysprof-trace", &proc_root);
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printk (KERN_ALERT "stopping sysprof module\n");
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}
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