/* * jiq.c -- the just-in-queue module * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files.  The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates.   No warranty is attached; * we cannot take responsibility for errors or fitness for use. * * $Id: jiq.c,v 1.15 2001/07/18 22:28:16 rubini Exp $ */ /* BUGS: the module is not reentrant: only one file can be read at a time *       the module usage count is not used: you could remove the module *           while reading it, thus asking for troubles. */#ifndef __KERNEL__#  define __KERNEL__#endif#ifndef MODULE#  define MODULE#endif#include <linux/config.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/fs.h>     /* everything... */#include <linux/proc_fs.h>#include <linux/errno.h>  /* error codes */#include <linux/tqueue.h>#include <linux/interrupt.h> /* intr_count */#include "sysdep.h"/* * This module is a silly one: it only embeds short code fragments * that show how enqueued tasks `feel' theit environment */#define LIMIT (PAGE_SIZE-128) /* don't print any more after this size *//* * Print information about the current environment. This is called from * within the task queues. If the limit is reched, awake the reading * process. */DECLARE_WAIT_QUEUE_HEAD (jiq_wait);struct tq_struct jiq_task; /* global: initialized to zero *//* * Keep track of info we need between task queue runs. */struct clientdata {    int len;    char *buf;    unsigned long jiffies;    task_queue *queue;} jiq_data;#define SCHEDULER_QUEUE ((task_queue *) 1)#ifdef HAVE_TASKLETSvoid jiq_print_tasklet (unsigned long);DECLARE_TASKLET (jiq_tasklet, jiq_print_tasklet, (unsigned long) &jiq_data);#endif /* HAVE_TASKLETS *//* * Do the printing; return non-zero if the task should be rescheduled. */int jiq_print(void *ptr){  struct clientdata *data = (struct clientdata *)ptr;  int len = data->len;  char *buf = data->buf;  unsigned long j = jiffies;  if (len > LIMIT) {       wake_up_interruptible(&jiq_wait);      return 0;  }  if (len == 0)      len = sprintf(buf,"    time  delta interrupt  pid cpu command\n");  else      len =0;  /* intr_count is only exported since 1.3.5, but 1.99.4 is needed anyways */  len += sprintf(buf+len,"%9li %3li        %i   %5i %3i %s\n",                 j, j - data->jiffies,                 in_interrupt (), current->pid, smp_processor_id (), current->comm);  data->len += len;  data->buf += len;  data->jiffies = j;  return 1;}/* * Call jiq_print from a task queue */void jiq_print_tq(void *ptr){    if (jiq_print (ptr)) {        struct clientdata *data = (struct clientdata *)ptr;        if (data->queue == SCHEDULER_QUEUE)	    schedule_task(&jiq_task);        else if (data->queue)            queue_task(&jiq_task, data->queue);        if (data->queue == &tq_immediate)            mark_bh(IMMEDIATE_BH); /* this one needs to be marked */    }}/* * Use the scheduler queue  -- /proc/jiqsched */int jiq_read_sched(char *buf, char **start, off_t offset,                   int len, int *eof, void *data){    jiq_data.len = 0;               /* nothing printed, yet */    jiq_data.buf = buf;             /* print in this place */    jiq_data.jiffies = jiffies;     /* initial time */    /* jiq_print will queue_task() again in jiq_data.queue */    jiq_data.queue = SCHEDULER_QUEUE;    schedule_task(&jiq_task);             /* ready to run */    interruptible_sleep_on(&jiq_wait);    /* sleep till completion */    *eof = 1;    return jiq_data.len;}#ifdef USE_PROC_REGISTERstatic int jiq_old_read_sched(char *buf, char **start, off_t offset, int len,                int unused){    int eof;    return jiq_read_sched(buf, start, offset, len, &eof, NULL);}struct proc_dir_entry jiq_proc_sched = {        0,                 /* low_ino: the inode -- dynamic */        8, "jiqsched",     /* len of name and name */        S_IFREG | S_IRUGO, /* mode */        1, 0, 0,           /* nlinks, owner, group */        0, NULL,           /* size - unused; operations -- use default */        &jiq_old_read_sched,   /* function used to read data */        /* nothing more */    };#endifint jiq_read_timer(char *buf, char **start, off_t offset,                   int len, int *eof, void *data){    jiq_data.len = 0;            /* nothing printed, yet */    jiq_data.buf = buf;          /* print in this place */    jiq_data.jiffies = jiffies;  /* initial time */    jiq_data.queue = &tq_timer;  /* re-register yourself here */    queue_task(&jiq_task, &tq_timer);     /* ready to run */    interruptible_sleep_on(&jiq_wait);    /* sleep till completion */    *eof = 1;    return jiq_data.len;}#ifdef USE_PROC_REGISTERstatic int jiq_old_read_timer(char *buf, char **start, off_t offset, int len,                int unused){    int eof;    return jiq_read_timer(buf, start, offset, len, &eof, NULL);}struct proc_dir_entry jiq_proc_timer = {        0,                 /* low_ino: the inode -- dynamic */        8, "jiqtimer",     /* len of name and name */        S_IFREG | S_IRUGO, /* mode */        1, 0, 0,           /* nlinks, owner, group */        0, NULL,           /* size - unused; operations -- use default */        &jiq_old_read_timer,   /* function used to read data */        /* nothing more */    };#endifint jiq_read_immed(char *buf, char **start, off_t offset,                   int len, int *eof, void *data){    jiq_data.len = 0;                /* nothing printed, yet */    jiq_data.buf = buf;              /* print in this place */    jiq_data.jiffies = jiffies;      /* initial time */    jiq_data.queue = &tq_immediate;  /* re-register yourself here */    queue_task(&jiq_task, &tq_immediate); /* ready to run */    mark_bh(IMMEDIATE_BH);    interruptible_sleep_on(&jiq_wait);    /* sleep till completion */    *eof = 1;    return jiq_data.len;}#ifdef USE_PROC_REGISTERstatic int jiq_old_read_immed(char *buf, char **start, off_t offset, int len,                int unused){    int eof;    return jiq_read_immed(buf, start, offset, len, &eof, NULL);}struct proc_dir_entry jiq_proc_immed = {        0,                 /* low_ino: the inode -- dynamic */        8, "jiqimmed",     /* len of name and name */        S_IFREG | S_IRUGO, /* mode */        1, 0, 0,           /* nlinks, owner, group */        0, NULL,           /* size - unused; operations -- use default */        &jiq_old_read_immed,   /* function used to read data */        /* nothing more */    };#endif#ifdef HAVE_TASKLETS/* * Call jiq_print from a tasklet */void jiq_print_tasklet(unsigned long ptr){    if (jiq_print ((void *) ptr))        tasklet_schedule (&jiq_tasklet);}int jiq_read_tasklet(char *buf, char **start, off_t offset, int len,                int *eof, void *data){    jiq_data.len = 0;                /* nothing printed, yet */    jiq_data.buf = buf;              /* print in this place */    jiq_data.jiffies = jiffies;      /* initial time */    tasklet_schedule(&jiq_tasklet);    interruptible_sleep_on(&jiq_wait);    /* sleep till completion */    *eof = 1;    return jiq_data.len;}/* No PROC_REGISTER junk since tasklets postdate all that */#endif /* HAVE_TASKLETS *//* * This one, instead, tests out the timers. */struct timer_list jiq_timer;void jiq_timedout(unsigned long ptr){    jiq_print((void *)ptr);            /* print a line */    wake_up_interruptible(&jiq_wait);  /* awake the process */}int jiq_read_run_timer(char *buf, char **start, off_t offset,                   int len, int *eof, void *data){    jiq_data.len = 0;           /* prepare the argument for jiq_print() */    jiq_data.buf = buf;    jiq_data.jiffies = jiffies;    jiq_data.queue = NULL;      /* don't requeue */    init_timer(&jiq_timer);              /* init the timer structure */    jiq_timer.function = jiq_timedout;    jiq_timer.data = (unsigned long)&jiq_data;    jiq_timer.expires = jiffies + HZ; /* one second */    jiq_print(&jiq_data);   /* print and go to sleep */    add_timer(&jiq_timer);    interruptible_sleep_on(&jiq_wait);    del_timer_sync(&jiq_timer);  /* in case a signal woke us up */        *eof = 1;    return jiq_data.len;}#ifdef USE_PROC_REGISTERstatic int jiq_old_read_run_timer(char *buf, char **start, off_t offset, int len,                int unused){    int eof;    return jiq_read_run_timer(buf, start, offset, len, &eof, NULL);}struct proc_dir_entry jiq_proc_run_timer = {        0,                 /* low_ino: the inode -- dynamic */        7, "jitimer",      /* len of name and name */        S_IFREG | S_IRUGO, /* mode */        1, 0, 0,           /* nlinks, owner, group */        0, NULL,           /* size - unused; operations -- use default */        &jiq_old_read_run_timer, /* function used to read data */        /* nothing more */    };#endif/* * the init/clean material */int jiq_init(void){    /* these lines are in jiq_init() */    jiq_task.routine = jiq_print_tq;    jiq_task.data = (void *)&jiq_data;#ifdef USE_PROC_REGISTER    proc_register_dynamic(&proc_root, &jiq_proc_sched);    proc_register_dynamic(&proc_root, &jiq_proc_timer);    proc_register_dynamic(&proc_root, &jiq_proc_immed);    proc_register_dynamic(&proc_root, &jiq_proc_run_timer);#else    create_proc_read_entry("jiqsched", 0, NULL, jiq_read_sched, NULL);    create_proc_read_entry("jiqtimer", 0, NULL, jiq_read_timer, NULL);    create_proc_read_entry("jiqimmed", 0, NULL, jiq_read_immed, NULL);    create_proc_read_entry("jitimer", 0, NULL, jiq_read_run_timer, NULL);#ifdef HAVE_TASKLETS    create_proc_read_entry("jiqtasklet", 0, NULL, jiq_read_tasklet, NULL);#endif#endif#ifndef JIT_DEBUG    EXPORT_NO_SYMBOLS;#endif    return 0; /* succeed */}void jiq_cleanup(void){#ifdef USE_PROC_REGISTER    proc_unregister(&proc_root, jiq_proc_sched.low_ino);    proc_unregister(&proc_root, jiq_proc_timer.low_ino);    proc_unregister(&proc_root, jiq_proc_immed.low_ino);    proc_unregister(&proc_root, jiq_proc_run_timer.low_ino);#else    remove_proc_entry("jiqsched", 0);    remove_proc_entry("jiqtimer", 0);    remove_proc_entry("jiqimmed", 0);    remove_proc_entry("jitimer", 0);#ifdef HAVE_TASKLETS    remove_proc_entry("jiqtasklet", 0);#endif#endif}module_init(jiq_init);module_exit(jiq_cleanup);