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Subject: RE: [Announce] Non Invasive Kernel Monitor for threads/processes
Date: Tue, 15 Jun 2004 15:48:02 -0700
Message-ID: <66539F0E7F15B44C9C0FC50D0FF024F7ABEA7D@orsmsx407>
Thread-Topic: [Announce] Non Invasive Kernel Monitor for threads/processes
Thread-Index: AcRTKdluQe5SlKbyTl65M8Tnq7xYSAAAMspA
From: "Sabharwal, Atul" <atul.sabharwal@intel.com>
To: "Atul Sabharwal" <atul_sabharwal@linux.jf.intel.com>,
       <linux-kernel@vger.kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
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http://marc.theaimsgroup.com/?l=linux-kernel&m=108732526008679&w=2

Same e-mail on an archive as part of the patch got munged.
--
Atul

-------------------------------------------------------------
P.S:  All opinions are my personal opinion(s) & responsibility and do
not represent the view of my employer ( Intel Corporation ).
 

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org 
>[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Atul Sabharwal
>Sent: Tuesday, June 15, 2004 12:54 PM
>To: linux-kernel@vger.kernel.org
>Subject: [Announce] Non Invasive Kernel Monitor for threads/processes
>
>We have been working with a solution for non-intrusively trapping on 
>lifetime
>of processes/threads. This is useful for management 
>applications running in
>telecom and enterprise data centers that need to monitor a set 
>of threads/
>processes.
>
>
>Project Goal::
>~~~~~~~~~~~~~~
>To create a kernel patch that  shall support methods to 
>non-intrusively 
>monitor
>processes/threads at the kernel level.  It would use a notfication 
>mechanism in
>the kernel that allows registration of events of interest regarding 
>processes/
>threads.  Events of interest could be the following : Process creation 
>(fork),
>Process exit(exit), Process calls(exec), thread creation & thread exit.
>The implementation needs to provide high performance with low overhead.
>Monitoring would be driven directly by the events in the kernel to 
>ensure low
>latency access to interesting events.
>
>Solution Approach:
>~~~~~~~~~~~~~~~~~~
>This method requires a user space process (called monitor) to 
>start and 
>stop
>monitoring in the system.  The monitor sends the list of pids and the 
>events
>to be monitored for that pid. Once the ioctl is received, the kernel 
>establishes
> a filter for it.  Events get flooded in the system as each 
>call (fork, 
>exec and
>exit) has been modified to generate events. The events which match the
>filter become interesting and require that a notification is 
>sent to the 
>monitor
>process.  Events which do no match the filter get dropped.  In 
>the case when
> we have multiple monitor processes, signals are sent to each 
>monitor whose
> filters match the event which has occurred.
>
>
>Solution Description :
>~~~~~~~~~~~~~~~~~~~~~~
>The registration and de-registration command are implemented 
>as ioctls. The
>notification command is implemented as a sigqueue signal. The 
>system calls
>such as fork, exit, and exec have been changed to add a notification 
>call to
>the monitor process.  The filter for events is populated with the 
>registration
>command. Events & their respective thread/process get removed from the
>filter with the de-registration command.
>
>Threads and processes follow the same code path for task creation & 
>termination.
>Hence, the code path is the same for threads and processes. 
>There is no 
>equivalent
>of an exec call with threads.  The only distinction for a 
>thread is that 
>in the task
>struct, the thread group id (tgid) and process id (pid) are different. 
>For a process,
>they are the same. 
>
>The signal used for notification is also specified with the 
>registration 
>command. 
>If it is a real-time signal, it would perform better as signals would 
>get queued
>for the monitor. With non-real time signals, signals would get dropped 
>if one
>signal exists. Hence, it is recommended to specify a real time signal. 
>Also, it is
> to be noted that the solution is totally architecture 
>independent. So, 
>would just
> need a re-compile on the respective platform.
>
>Kmonitor has been implemented as a miscellaneous character 
>driver built 
>into
>the Linux kernel. It cannot be compiled as a loadable module.  It 
>supports the
>relevant driver calls for open, release, ioctl, init, cleanup calls.  
>The character
> driver code contains the filtering, registration/de-registration and 
>notification
>functions of Kmonitor as wells as routines to manage the 
>linked list(s) 
>for filtering.
>
>Kmonitor has 256 buckets and each bucket contains a spinlock and a 
>linked list.
>This works around the sequential search operation in linked list by 
>using a hashing
>function to change the complexity from O(N) to O(N/M) where M 
>is the number
>of buckets.
>
>Kernel Version & Code location:
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>The kernel used was the 2.6.6 kernel and the code is at 
>http://kmonitor.bkbits.net
>
>User space programs:
>~~~~~~~~~~~~~~~~~~~~
>1. unit_test : A sample program to monitor future processes.
>    
>http://kmonitor.bkbits.net:8080/tools/anno/unit_test.c@1.4?nav=
>index.html|ChangeSet@-3w|cset@1.35 
>
>
>2. monitor_pid: A sample program to monitor a process sub-tree.
>    
>http://kmonitor.bkbits.net:8080/tools/anno/monitor_pid.c@1.2?na
>v=index.html|ChangeSet@-2w|cset@1.37 
>
>
>3. wait_on_pid : A sample program which waits till a pid dies.
>    
>http://kmonitor.bkbits.net:8080/tools/anno/wait_on_pid.c@1.5?na
>v=index.html|ChangeSet@-2w|cset@1.37 
>
>
>Source Code:
>~~~~~~~~~~~~
>The patch for Kmonitor is as below :
>
>
>diff -Nru a/Documentation/ioctl-number.txt 
>b/Documentation/ioctl-number.txt
>--- a/Documentation/ioctl-number.txt    2004-06-14 11:24:08 -07:00
>+++ b/Documentation/ioctl-number.txt    2004-06-14 11:24:08 -07:00
>@@ -189,3 +189,4 @@
>                    <mailto:michael.klein@puffin.lb.shuttle.de>
>0xDD    00-3F    ZFCP device driver    see drivers/s390/scsi/
>                    <mailto:aherrman@de.ibm.com>
>+0xDE    all    drivers/char/kmonitor    
><mailto:atul.sabharwal@intel.com>
>diff -Nru a/Documentation/kmonitor.txt b/Documentation/kmonitor.txt
>--- /dev/null    Wed Dec 31 16:00:00 196900
>+++ b/Documentation/kmonitor.txt    2004-06-14 11:24:08 -07:00
>@@ -0,0 +1,119 @@
>+Enabling Non-intrusive Application Monitoring with kmonitor
>+-----------------------------------------------------------
>+The kmonitor driver implements a kernel level non-intrusive 
>+mechanism 
>for rapidly notifying a monitoring user space process
>+of key (process/thread creation/exit) kernel events.
>+
>+The monitoring user space process registers and deregisters 
>for events via
>+a new misc char device using two new ioctl's.  The kernel notifies the
>+monitoring process(es) of the events via a signal that the monitor 
>specifies
>+during registration.
>+
>+An example of how this would be used in an minimal command 
>line utility
>+to wait for an arbitrary process to exit:
>+
>+<snip>rest of required headers...</snip>
>+#include <linux/kmonitor.h>
>+
>+void target_exit_handler (int signum , struct siginfo * info, 
>void * buf)
>+{
>+     /*
>+      * Since we only registered for one type of event,
>+      * KMONITOR_PROCESS_EXIT, on one process, then we 
>already +      * 
>know our target process has exited
>+      *
>+      * If we were doing something more complex, then the data in
>+      * info might be usefull:
>+      * 1. info->si_pid: process id of target process
>+      * 2. info->si_gid: group id of target process
>+      * 3. info->si_int: event that triggered this signal
>+      *    (See include/linux/kmonitor.h for the list of events)
>+      *
>+      * The target process has exited, so we are done. Kmonitor
>+      * will do cleanup when we close the file descriptor for 
>+      * 
>/dev/kmonitor (which will happen automatically when we
>+      * exit.)
>+      */
>+    exit(0);
>+}
>+
>+int main(int argc, char *argv[])
>+{
>+<snip>...</snip>
>+
>+    /*
>+     * kmonitor will notify us that the target process has exited
>+     * by sending us a real-time signal with the payload containing
>+     * the event that triggered the notification.
>+     */
>+    action.sa_sigaction = target_exit_handler;
>+    action.sa_flags = SA_SIGINFO;
>+    if (-1 == sigaction(SIGRTMIN, &action, NULL)) {
>+        perror("sigaction");
>+        exit(-1);
>+    }
>+
>+    /*
>+     * The kmonitor is implemented as misc char device, so the
>+     * file that needs to be opened (assumed to be /dev/kmonitor
>+     * in this example) is a char device with a major number of 10
>+     * and a minor number of 221.
>+     * +     * mknod /dev/kmonitor c 10 221 +     */
>+    fd = open("/dev/kmonitor", O_WRONLY);
>+    if (-1 == fd) {
>+        perror("open /dev/kmonitor");
>+        exit(-1);
>+    }
>+
>+    /*
>+     * To sign up for notification of an arbitrary event on an
>+     * arbitrary process then we send the KMONITOR_IOW_REGISTER
>+     * command to the device via the ioctl system call.
>+     *
>+     * We indicate the target process and event by sending a
>+     * kmonitor_cmd structure.
>+     *
>+     * NOTE: The 'type' field in the structure is actually +     
>*       a bitmask, so it is possible to register for
>+     *       multiple events on a given target process in one
>+     *       ioctl call.  The possible events are...
>+         *       #define KMONITOR_THREAD_CREATE 0x01 +        
> *       
>#define KMONITOR_THREAD_ABORT  0x02           +         *      
> #define 
>KMONITOR_THREAD_EXIT   0x04
>+         *       #define KMONITOR_PROCESS_FORK  0x08
>+         *       #define KMONITOR_PROCESS_ABORT 0x10 +        
> *       
>#define KMONITOR_PROCESS_EXEC  0x20 +         *       #define 
>KMONITOR_PROCESS_EXIT  0x40
>+     */
>+    hdr.signal = SIGRTMIN;
>
>+    hdr.pid = args.pid;
>+    hdr.type = KMONITOR_PROCESS_EXIT;
>+    if (-1 == ioctl(fd, KMONITOR_IOW_REGISTER, &hdr)) {
>+        perror("ioctl");
>+        exit(-1);
>+    }
>+   
>+    /*
>+     * In this very simple example all we need to do is wait +     * 
>for a signal to be sent.  The signal handler will exit
>+     * when it is notified of the target process exiting.
>+     */
>+    sigemptyset(&empty_mask);
>+    sigsuspend(&empty_mask);   
>+
>+    /*
>+     * kmonitor will perform a cleanup of all request a given +     * 
>monitoring process has made, so it is required to deregister
>+     * each of the specific request.
>+     *
>+     * If for some reason a monitoring process wanted to deregister
>+     * a specific request, then the procedure is just like 
>registering,
>+     * other then the ioctl command is KMONITOR_IOW_DEREGISTER.
>+     */
>+    close(fd);
>+    exit (0);
>+}
>+
>+
>diff -Nru a/drivers/char/Kconfig b/drivers/char/Kconfig
>--- a/drivers/char/Kconfig    2004-06-14 11:24:08 -07:00
>+++ b/drivers/char/Kconfig    2004-06-14 11:24:08 -07:00
>@@ -974,5 +974,15 @@
>      out to lunch past a certain margin.  It can reboot the system
>      or merely print a warning.
>
>+config KMONITOR
>+    bool "Kmonitor driver"
>+    help
>+      The kmonitor driver implements a kernel level non-intrusive 
>+      mechanism for rapidly notifying a monitoring user space process
>+      of key (process/thread creation/exit) kernel events. For more
>+      info see Documentation/kmonitor.txt +
>+      If in doubt, say 'N'.
>+
>endmenu
>
>diff -Nru a/drivers/char/Makefile b/drivers/char/Makefile
>--- a/drivers/char/Makefile    2004-06-14 11:24:08 -07:00
>+++ b/drivers/char/Makefile    2004-06-14 11:24:08 -07:00
>@@ -79,6 +79,7 @@
>obj-$(CONFIG_DRM) += drm/
>obj-$(CONFIG_PCMCIA) += pcmcia/
>obj-$(CONFIG_IPMI_HANDLER) += ipmi/
>+obj-$(CONFIG_KMONITOR) += kmonitor.o
>
>obj-$(CONFIG_HANGCHECK_TIMER) += hangcheck-timer.o
>
>diff -Nru a/drivers/char/kmonitor.c b/drivers/char/kmonitor.c
>--- /dev/null    Wed Dec 31 16:00:00 196900
>+++ b/drivers/char/kmonitor.c    2004-06-14 11:24:08 -07:00
>@@ -0,0 +1,336 @@
>+/*
>+ * linux/kmonitor.c
>+ *
>+ * Copyright (C)  2004 Intel Corporation.  All rights reserved.
>+ *
>+ * This program is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU General Public
>+ * License v2.0 as published by the Free Software Foundation; + *
>+ * This program is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU General Public
>+ * License along with this program; if not, write to the
>+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
>+ * Boston, MA 021110-1307, USA.
>+ *
>+ * Authors: Atul Sabharwal <atul.sabharwal@intel.com>
>+ *
>+ * The kmonitor driver implements a kernel level non-intrusive + * 
>mechanism for rapidly notifying a monitoring user space process
>+ * of key (process/thread creation/exit) kernel events.
>+ * + * See Documentation/kmonitor.txt for more details
>+ */
>+
>+#include <linux/config.h>
>+#include <linux/module.h>
>+#include <linux/moduleparam.h>
>+#include <linux/fs.h>
>+#include <linux/hash.h>
>+#include <linux/init.h>
>+#include <linux/kmonitor.h>
>+#include <linux/miscdevice.h>
>+#include <linux/proc_fs.h>
>+#include <linux/sched.h>
>+#include <linux/types.h>
>+#include <linux/timer.h>
>+#include <asm/uaccess.h>
>+#include <asm/atomic.h>
>+
>+/*
>+ * kmonitor maintains a database of resources containing:
>+ * - the pid of the process being monitored (target)
>+ * - the pid of process that should be notified (monitor)
>+ * - an event mask + * - a signal number to notify the monitor with
>+ * - a list_head
>+ * + * To improve scalability, a hash of linked listed is maintained
>+ * with a per bucket read-write lock.  KMONITOR_BITS defines the
>+ * order of the list size, so setting KMONITOR_BITS to 8 
>would translate
>+ * to 256 buckets.  Using a hash of linked list improves the 
>order of the
>+ * search from an O(n) to O(n/m) where n is the number of 
>resources and
>+ * m is the number of buckets.
>+ *
>+ * Note that since we are using a per bucket read-write lock, 
>the number
>+ * of buckets also as an effect on SMP performance since the 
>smaller the
>+ * list of resources in each bucket, the less likely a 
>processor will + 
>* spin waiting for another processor to finish writing to the 
>same list.
>+ */
>+
>+struct kmonitor_bucket +{
>+    struct list_head list;
>+    rwlock_t lock;
>+};
>+
>+#define KMONITOR_BITS 0x8
>+
>+struct kmonitor_bucket kmonitor_resources[1<<KMONITOR_BITS];
>+
>+static inline unsigned long khash(pid_t target)
>+{
>+    return hash_long((unsigned long)target, KMONITOR_BITS);
>+}
>+
>+struct kmonitor_res
>+{
>+    struct list_head rlist;
>+    pid_t target;
>+    pid_t monitor;
>+    int signal;
>+    __u32 event_mask;
>+};
>+
>+#define to_kmonitor_res(r) \
>+        container_of(r, struct kmonitor_res, rlist);
>+
>+kmem_cache_t *kmonitor_cache;
>+
>+/*
>+ * kmonitor_active is used to improve the performance of searching
>+ * an empty resource database
>+ */
>+atomic_t kmonitor_active = { .counter = 0};
>+
>+/* #define DEBUG */
>+#ifdef DEBUG
>+#define DBG(format, arg...) printk("%s: " format "\n", __FUNCTION__ , 
>## arg)
>+#define TRACE(format, arg...) printk("%s(" format ")\n", 
>__FUNCTION__, 
>## arg)
>+#else
>+#define DBG(format, arg...) do {} while(0);
>+#define TRACE(arg...) do {} while(0);
>+#endif
>+
>+static int kmonitor_add(pid_t target, int type, int signal)
>+{
>+    struct kmonitor_res *r;
>+    struct list_head *tmp;
>+    unsigned long bucket = khash(target);
>+
>+    TRACE("%i, %i, %i", target, type, signal);
>+    read_lock(&kmonitor_resources[bucket].lock);
>+    list_for_each(tmp, &kmonitor_resources[bucket].list) {
>+        r = to_kmonitor_res(tmp);
>+        if (r->monitor == current->pid && r->target == target) {
>+            /*
>+             * There is an existing resource for this
>+             * target/monitor combination so just flip +      
>       * 
>a bit in the event mask indicating that +             * this monitor 
>also wants to be notified +             * for this type of event.
>+             */
>+            r->event_mask |= type;
>+            r->signal = signal;
>+            DBG("Added %i to existing res", type);
>+            read_unlock(&kmonitor_resources[bucket].lock);
>+            return 0;
>+        } +    }
>+    read_unlock(&kmonitor_resources[bucket].lock);
>+
>+    /*
>+     * This is the first event registered for this target +     * on 
>this monitor.  Allocate a new resource from our +     * cache and add 
>the resource to the global list.
>+     *
>+         * Note: There is no race condition between the top half & the
>+         * bottom part of this function as if multiple monitors are 
>active,
>+         * each will have a unique resource for itself. So, 
>the function
>+         * is SMP safe.
>+         */
>+    r = kmem_cache_alloc(kmonitor_cache, SLAB_KERNEL);
>+    if (!r)
>+        return -ENOMEM;
>+       
>+    r->target = target;
>+    r->monitor = current->pid;
>+    r->event_mask = type;
>+    r->signal = signal;
>+    write_lock(&kmonitor_resources[bucket].lock);
>+    list_add(&r->rlist, &kmonitor_resources[bucket].list);
>+    write_unlock(&kmonitor_resources[bucket].lock);
>+    return 0;
>+}
>+
>+static int kmonitor_remove(pid_t target, int type)
>+{
>+    struct list_head *tmp, *next;
>+    int ret = -EINVAL;
>+    int bucket = khash(target);
>+
>+    TRACE("%i, %i", target, type);
>+
>+    write_lock(&kmonitor_resources[bucket].lock);
>+    list_for_each_safe(tmp, next, &kmonitor_resources[bucket].list) {
>+        struct kmonitor_res *r = to_kmonitor_res(tmp);
>+        if (r->monitor == current->pid && r->target == target) {
>+            r->event_mask &= ~type;
>+            if (!r->event_mask) {
>+                /* No more events so go ahead and cleanup */
>+                list_del(tmp);
>+                kmem_cache_free(kmonitor_cache, r);
>+            }
>+            ret = 0;
>+            break;
>+        } +    }
>+
>+    write_unlock(&kmonitor_resources[bucket].lock);
>+    return ret;
>+}
>+
>+void __kmonitor_notify_event(struct task_struct *tsk, int type) +{
>+    struct siginfo info;
>+    struct list_head *tmp, *next;
>+    int bucket = khash(current->pid);
>+
>+    read_lock(&kmonitor_resources[bucket].lock);
>+    list_for_each_safe(tmp,next,&kmonitor_resources[bucket].list) {
>+        struct kmonitor_res *r = to_kmonitor_res(tmp);
>+        if (r->target == current->pid && type & r->event_mask) {
>+            info.si_signo = r->signal;
>+            info.si_code = SI_QUEUE;
>+            info.si_int = type;
>+            info.si_pid = tsk->pid;
>+            info.si_uid = tsk->uid;
>+            kill_proc_info(r->signal, &info, r->monitor);
>+        }
>+    }
>+    read_unlock(&kmonitor_resources[bucket].lock);
>+}
>+
>+static int kmonitor_open(struct inode *inode, struct file *file)
>+{
>+    atomic_inc(&kmonitor_active);
>+    return 0;
>+}
>+
>+static int kmonitor_release(struct inode *inode, struct file *file)
>+{
>+    struct list_head *tmp, *next;
>+    int i;
>+
>+    TRACE("%p, %p", inode, file);
>+    atomic_dec(&kmonitor_active);
>+
>+    /*
>+     * Remove any resources associated with this monitor
>+     */
>+    for (i=0; i<(1<<KMONITOR_BITS); i++) {
>+        write_lock(&kmonitor_resources[i].lock);
>+        list_for_each_safe(tmp, next, &kmonitor_resources[i].list) {
>+            struct kmonitor_res *r = to_kmonitor_res(tmp);
>+            if (r->monitor == current->pid) {
>+                list_del(tmp);
>+                kmem_cache_free(kmonitor_cache, r);
>+            } +        }
>+        write_unlock(&kmonitor_resources[i].lock);
>+    }
>+
>+    return 0;
>+}
>+
>+static int kmonitor_ioctl(struct inode *inode, struct file *file,
>+              unsigned int cmd, unsigned long arg)
>+{
>+    struct kmonitor_cmd hdr;
>+
>+    TRACE("%p, %p, %i, %i", inode, file, (int)cmd, (int)arg);
>+    if (copy_from_user((struct kmonitor_cmd *)&hdr, +               
>(struct kmonitor_cmd *)arg, +               sizeof(struct 
>kmonitor_cmd)))
>+        return -EFAULT;
>+
>+    switch (cmd) {
>+    case KMONITOR_IOW_REGISTER:
>+        return kmonitor_add(hdr.pid, hdr.type, hdr.signal);
>+    case KMONITOR_IOW_DEREGISTER:
>+        return kmonitor_remove(hdr.pid, hdr.type);       
>+    }
>+
>+    DBG("Unexpected ioctl, %i", cmd);
>+    return -EINVAL;
>+}
>+
>+static struct file_operations kmonitor_fops = {
>+    .owner        = THIS_MODULE,
>+    .llseek        = no_llseek,
>+    .open           = kmonitor_open,
>+    .release    = kmonitor_release,
>+    .ioctl          = kmonitor_ioctl,
>+};
>+
>+static struct miscdevice kmonitor_miscdev = {
>+    .minor        = KMONITOR_MINOR,
>+    .name        = "kmonitor",
>+    .fops        = &kmonitor_fops,
>+};
>+
>+static int __init kmonitor_init(void)
>+{
>+    int ret, i;
>+
>+    TRACE("void");
>+
>+    for (i=0; i<(1<<KMONITOR_BITS); i++) {
>+        INIT_LIST_HEAD(&kmonitor_resources[i].list);
>+        kmonitor_resources[i].lock = RW_LOCK_UNLOCKED;
>+    }
>+
>+    ret = misc_register(&kmonitor_miscdev);
>+    if (ret) {
>+        printk(KERN_ERR "unable to register kmonitor misc device\n");
>+        goto error_misc_drvr_register;
>+    }
>+
>+    kmonitor_cache = kmem_cache_create("kmonitor_res", 
>+                       sizeof(struct kmonitor_res), 0, 
>+                       SLAB_HWCACHE_ALIGN,
>+                       NULL, NULL);
>+    if (!kmonitor_cache) {
>+        printk(KERN_ERR "unable to allocate kmonitor_cache\n");
>+        ret = -EINVAL;
>+        goto error_in_kmonitor_cache;
>+    }
>+
>+    return 0;
>+
>+ error_in_kmonitor_cache:
>+    misc_deregister(&kmonitor_miscdev);
>+ error_misc_drvr_register:
>+    return ret;
>+}
>+
>+static void __exit kmonitor_exit(void)
>+{
>+    struct list_head *tmp, *next;
>+    int i;
>+
>+    TRACE("void");
>+    misc_deregister(&kmonitor_miscdev);
>+    for (i=0; i<(1<<KMONITOR_BITS); i++) {
>+        write_lock(&kmonitor_resources[i].lock);
>+        list_for_each_safe(tmp, next, &kmonitor_resources[i].list) {
>+            struct kmonitor_res *r = to_kmonitor_res(tmp);
>+            list_del(tmp);
>+            kmem_cache_free(kmonitor_cache, r);
>+        }
>+        write_unlock(&kmonitor_resources[i].lock);
>+    }
>+    kmem_cache_destroy(kmonitor_cache);
>+}
>+
>+module_init(kmonitor_init);
>+module_exit(kmonitor_exit);
>+
>+MODULE_AUTHOR("Atul Sabharwal");
>+MODULE_DESCRIPTION("Kmonitor Char Driver");
>+MODULE_LICENSE("GPL");
>+MODULE_ALIAS_MISCDEV(KMONITOR_MINOR);
>diff -Nru a/fs/exec.c b/fs/exec.c
>--- a/fs/exec.c    2004-06-14 11:24:08 -07:00
>+++ b/fs/exec.c    2004-06-14 11:24:08 -07:00
>@@ -46,6 +46,7 @@
>#include <linux/security.h>
>#include <linux/syscalls.h>
>#include <linux/rmap.h>
>+#include <linux/kmonitor.h>
>
>#include <asm/uaccess.h>
>#include <asm/pgalloc.h>
>@@ -1144,6 +1145,7 @@
>        free_arg_pages(&bprm);
>
>        /* execve success */
>+        kmonitor_notify_event(current, KMONITOR_PROCESS_EXEC);
>        security_bprm_free(&bprm);
>        return retval;
>    }
>diff -Nru a/include/linux/kmonitor.h b/include/linux/kmonitor.h
>--- /dev/null    Wed Dec 31 16:00:00 196900
>+++ b/include/linux/kmonitor.h    2004-06-14 11:24:08 -07:00
>@@ -0,0 +1,62 @@
>+/* + *
>+ * linux/kmonitor.h
>+ *
>+ * Copyright (C) 2004 Intel Corporation.  All rights reserved.
>+ *
>+ * This program is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU General Public
>+ * License v2.0 as published by the Free Software Foundation; + *
>+ * This program is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU General Public
>+ * License along with this program; if not, write to the
>+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
>+ * Boston, MA 021110-1307, USA.
>+ *
>+ * Authors: Atul Sabharwal <atul.sabharwal@intel.com>
>+ *               + */
>+#ifndef _LINUX_KMONITOR_H_
>+#define _LINUX_KMONITOR_H_
>+
>+#include <asm/atomic.h>
>+
>+#define KMONITOR_THREAD_CREATE 0x01 +#define KMONITOR_THREAD_ABORT  
>0x02           +#define KMONITOR_THREAD_EXIT   0x04
>+#define KMONITOR_PROCESS_FORK  0x08
>+#define KMONITOR_PROCESS_ABORT 0x10 +#define KMONITOR_PROCESS_EXEC  
>0x20 +#define KMONITOR_PROCESS_EXIT  0x40
>+
>+struct kmonitor_cmd +{
>+    pid_t pid;
>+    int type;
>+    int signal;
>+};
>+
>+#define KMONITOR_IOW_REGISTER   _IOW(0xDE, 1, struct kmonitor_cmd)
>+#define KMONITOR_IOW_DEREGISTER _IOW(0xDE, 2, struct kmonitor_cmd)
>+
>+#ifdef __KERNEL__
>+#include <linux/sysctl.h>
>+
>+extern  atomic_t  kmonitor_active;
>+extern void __kmonitor_notify_event(struct task_struct *tsk, 
>int type);
>+
>+static inline void kmonitor_notify_event( struct task_struct 
>*tsk, int 
>type)
>+{
>+#ifdef CONFIG_KMONITOR   
>+    if (atomic_read(&kmonitor_active))
>+        __kmonitor_notify_event(tsk, type);
>+#endif /* CONFIG_KMONITOR */
>+}
>+#endif /* __KERNEL__ */
>+#endif /* _LINUX_KMONITOR_H_ */
>+
>diff -Nru a/include/linux/miscdevice.h b/include/linux/miscdevice.h
>--- a/include/linux/miscdevice.h    2004-06-14 11:24:08 -07:00
>+++ b/include/linux/miscdevice.h    2004-06-14 11:24:08 -07:00
>@@ -35,6 +35,7 @@
>#define SGI_USEMACLONE         151
>
>#define TUN_MINOR         200
>+#define KMONITOR_MINOR         221
>
>struct device;
>
>diff -Nru a/kernel/exit.c b/kernel/exit.c
>--- a/kernel/exit.c    2004-06-14 11:24:08 -07:00
>+++ b/kernel/exit.c    2004-06-14 11:24:08 -07:00
>@@ -22,6 +22,7 @@
>#include <linux/profile.h>
>#include <linux/mount.h>
>#include <linux/proc_fs.h>
>+#include <linux/kmonitor.h>
>
>#include <asm/uaccess.h>
>#include <asm/pgtable.h>
>@@ -748,6 +749,11 @@
>     */
>    _raw_write_unlock(&tasklist_lock);
>    local_irq_enable();
>+
>+    if (tsk->pid == tsk->tgid)
>+        kmonitor_notify_event(tsk, KMONITOR_PROCESS_EXIT);
>+    else
>+        kmonitor_notify_event(tsk, KMONITOR_THREAD_EXIT);
>
>    /* If the process is dead, release it - nobody will wait for it */
>    if (state == TASK_DEAD)
>diff -Nru a/kernel/fork.c b/kernel/fork.c
>--- a/kernel/fork.c    2004-06-14 11:24:08 -07:00
>+++ b/kernel/fork.c    2004-06-14 11:24:08 -07:00
>@@ -41,6 +41,7 @@
>#include <asm/mmu_context.h>
>#include <asm/cacheflush.h>
>#include <asm/tlbflush.h>
>+#include <linux/kmonitor.h>
>
>/* The idle threads do not count..
> * Protected by write_lock_irq(&tasklist_lock)
>@@ -1167,6 +1168,11 @@
>
>    if (!IS_ERR(p)) {
>        struct completion vfork;
>+
>+                if (p->pid == p->tgid)
>+                        kmonitor_notify_event(p, 
>KMONITOR_PROCESS_FORK);
>+                else
>+                        kmonitor_notify_event(p, 
>KMONITOR_THREAD_CREATE);
>
>        if (clone_flags & CLONE_VFORK) {
>            p->vfork_done = &vfork;
>
>
>-
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