lkml.org 
[lkml]   [2005]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[patch 1/2] fork_connector: add a fork connector
    From
    Date
      This patch adds a fork connector in the do_fork() routine. It sends a
    netlink datagram when enabled. The message can be read by a user space
    application. By this way, the user space application is alerted when a
    fork occurs.

    It uses the userspace <-> kernelspace connector that works on top of
    the netlink protocol. The fork connector is enabled or disabled by
    sending a message to the connector. This operation should be done by
    only one application. Such application can be downloaded from
    http://cvs.sourceforge.net/viewcvs.py/elsa/elsa_project/utils/fcctl.c

    The unique sequence number of messages can be used to check if a
    message is lost. This sequence number is relative to a CPU.

    The lmbench shows that the overhead (the construction and the sending
    of the message) in the fork() routine is around 7%.

    This patch applies to 2.6.12-rc1-mm3. Some other patches are needed
    that fix problems in the connector.c file. At least, you need to apply
    the patch provided in the second email.

    Signed-off-by: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
    ---

    drivers/connector/Kconfig | 11 ++++
    drivers/connector/Makefile | 1
    drivers/connector/cn_fork.c | 104 ++++++++++++++++++++++++++++++++++++++++++++
    include/linux/connector.h | 8 +++
    kernel/fork.c | 44 ++++++++++++++++++
    5 files changed, 168 insertions(+)


    Index: linux-2.6.12-rc1-mm3-cnfork/drivers/connector/Kconfig
    ===================================================================
    --- linux-2.6.12-rc1-mm3-cnfork.orig/drivers/connector/Kconfig 2005-03-25 09:47:09.000000000 +0100
    +++ linux-2.6.12-rc1-mm3-cnfork/drivers/connector/Kconfig 2005-03-25 10:14:21.000000000 +0100
    @@ -10,4 +10,15 @@ config CONNECTOR
    Connector support can also be built as a module. If so, the module
    will be called cn.ko.

    +config FORK_CONNECTOR
    + bool "Enable fork connector"
    + depends on CONNECTOR=y
    + default y
    + ---help---
    + It adds a connector in kernel/fork.c:do_fork() function. When a fork
    + occurs, netlink is used to transfer information about the parent and
    + its child. This information can be used by a user space application.
    + The fork connector can be enable/disable by sending a message to the
    + connector with the corresponding group id.
    +
    endmenu
    Index: linux-2.6.12-rc1-mm3-cnfork/drivers/connector/Makefile
    ===================================================================
    --- linux-2.6.12-rc1-mm3-cnfork.orig/drivers/connector/Makefile 2005-03-25 09:47:09.000000000 +0100
    +++ linux-2.6.12-rc1-mm3-cnfork/drivers/connector/Makefile 2005-03-25 10:14:21.000000000 +0100
    @@ -1,2 +1,3 @@
    obj-$(CONFIG_CONNECTOR) += cn.o
    +obj-$(CONFIG_FORK_CONNECTOR) += cn_fork.o
    cn-objs := cn_queue.o connector.o
    Index: linux-2.6.12-rc1-mm3-cnfork/drivers/connector/cn_fork.c
    ===================================================================
    --- linux-2.6.12-rc1-mm3-cnfork.orig/drivers/connector/cn_fork.c 2003-01-30 11:24:37.000000000 +0100
    +++ linux-2.6.12-rc1-mm3-cnfork/drivers/connector/cn_fork.c 2005-03-25 10:14:21.000000000 +0100
    @@ -0,0 +1,104 @@
    +/*
    + * cn_fork.c
    + *
    + * 2005 Copyright (c) Guillaume Thouvenin <guillaume.thouvenin@bull.net>
    + * 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 as published by
    + * the Free Software Foundation; either version 2 of the License, or
    + * (at your option) any later version.
    + *
    + * 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 02111-1307 USA
    + */
    +
    +#include <linux/module.h>
    +#include <linux/kernel.h>
    +#include <linux/init.h>
    +
    +#include <linux/connector.h>
    +
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Guillaume Thouvenin <guillaume.thouvenin@bull.net>");
    +MODULE_DESCRIPTION("Enable or disable the usage of the fork connector");
    +
    +int cn_fork_enable = 0;
    +struct cb_id cb_fork_id = { CN_IDX_FORK, CN_VAL_FORK };
    +
    +static inline void cn_fork_send_status(void)
    +{
    + /* TODO */
    + printk(KERN_INFO "cn_fork_enable == %d\n", cn_fork_enable);
    +}
    +
    +/**
    + * cn_fork_callback - enable or disable the fork connector
    + * @data: message send by the connector
    + *
    + * The callback allows to enable or disable the sending of information
    + * about fork in the do_fork() routine. To enable the fork, the user
    + * space application must send the integer 1 in the data part of the
    + * message. To disable the fork connector, it must send the integer 0.
    + */
    +static void cn_fork_callback(void *data)
    +{
    + struct cn_msg *msg = (struct cn_msg *)data;
    + int action;
    +
    + if (cn_already_initialized && (msg->len == sizeof(cn_fork_enable))) {
    + memcpy(&action, msg->data, sizeof(cn_fork_enable));
    + switch(action) {
    + case FORK_CN_START:
    + cn_fork_enable = 1;
    + break;
    + case FORK_CN_STOP:
    + cn_fork_enable = 0;
    + break;
    + case FORK_CN_STATUS:
    + cn_fork_send_status();
    + break;
    + }
    + }
    +}
    +
    +/**
    + * cn_fork_init - initialization entry point
    + *
    + * This routine will be run at kernel boot time because this driver is
    + * built in the kernel. It adds the connector callback to the connector
    + * driver.
    + */
    +static int cn_fork_init(void)
    +{
    + int err;
    +
    + err = cn_add_callback(&cb_fork_id, "cn_fork", &cn_fork_callback);
    + if (err) {
    + printk(KERN_WARNING "Failed to register cn_fork\n");
    + return -EINVAL;
    + }
    +
    + printk(KERN_NOTICE "cn_fork is registered\n");
    + return 0;
    +}
    +
    +/**
    + * cn_fork_exit - exit entry point
    + *
    + * As this driver is always statically compiled into the kernel the
    + * cn_fork_exit has no effect.
    + */
    +static void cn_fork_exit(void)
    +{
    + cn_del_callback(&cb_fork_id);
    +}
    +
    +module_init(cn_fork_init);
    +module_exit(cn_fork_exit);
    Index: linux-2.6.12-rc1-mm3-cnfork/include/linux/connector.h
    ===================================================================
    --- linux-2.6.12-rc1-mm3-cnfork.orig/include/linux/connector.h 2005-03-25 09:47:11.000000000 +0100
    +++ linux-2.6.12-rc1-mm3-cnfork/include/linux/connector.h 2005-03-25 10:14:21.000000000 +0100
    @@ -28,10 +28,16 @@
    #define CN_VAL_KOBJECT_UEVENT 0x0000
    #define CN_IDX_SUPERIO 0xaabb /* SuperIO subsystem */
    #define CN_VAL_SUPERIO 0xccdd
    +#define CN_IDX_FORK 0xfeed /* fork events */
    +#define CN_VAL_FORK 0xbeef


    #define CONNECTOR_MAX_MSG_SIZE 1024

    +#define FORK_CN_STOP 0
    +#define FORK_CN_START 1
    +#define FORK_CN_STATUS 2
    +
    struct cb_id
    {
    __u32 idx;
    @@ -133,6 +139,8 @@ struct cn_dev
    };

    extern int cn_already_initialized;
    +extern int cn_fork_enable;
    +extern struct cb_id cb_fork_id;

    int cn_add_callback(struct cb_id *, char *, void (* callback)(void *));
    void cn_del_callback(struct cb_id *);
    Index: linux-2.6.12-rc1-mm3-cnfork/kernel/fork.c
    ===================================================================
    --- linux-2.6.12-rc1-mm3-cnfork.orig/kernel/fork.c 2005-03-25 09:47:11.000000000 +0100
    +++ linux-2.6.12-rc1-mm3-cnfork/kernel/fork.c 2005-03-25 10:14:21.000000000 +0100
    @@ -41,6 +41,7 @@
    #include <linux/profile.h>
    #include <linux/rmap.h>
    #include <linux/acct.h>
    +#include <linux/connector.h>

    #include <asm/pgtable.h>
    #include <asm/pgalloc.h>
    @@ -63,6 +64,47 @@ DEFINE_PER_CPU(unsigned long, process_co

    EXPORT_SYMBOL(tasklist_lock);

    +#ifdef CONFIG_FORK_CONNECTOR
    +
    +#define CN_FORK_INFO_SIZE 64
    +#define CN_FORK_MSG_SIZE (sizeof(struct cn_msg) + CN_FORK_INFO_SIZE)
    +
    +static DEFINE_PER_CPU(unsigned long, fork_counts);
    +
    +static inline void fork_connector(pid_t parent, pid_t child)
    +{
    + if (cn_fork_enable) {
    + struct cn_msg *msg;
    + __u8 buffer[CN_FORK_MSG_SIZE];
    +
    + msg = (struct cn_msg *)buffer;
    +
    + memcpy(&msg->id, &cb_fork_id, sizeof(msg->id));
    +
    + msg->ack = 0; /* not used */
    + msg->seq = get_cpu_var(fork_counts)++;
    +
    + /*
    + * size of data is the number of characters
    + * printed plus one for the trailing '\0'
    + */
    + memset(msg->data, '\0', CN_FORK_INFO_SIZE);
    + msg->len = scnprintf(msg->data, CN_FORK_INFO_SIZE-1,
    + "%i %i %i",
    + smp_processor_id(), parent, child) + 1;
    +
    + put_cpu_var(fork_counts);
    +
    + cn_netlink_send(msg, CN_IDX_FORK);
    + }
    +}
    +#else
    +static inline void fork_connector(pid_t parent, pid_t child)
    +{
    + return;
    +}
    +#endif /* CONFIG_FORK_CONNECTOR */
    +
    int nr_processes(void)
    {
    int cpu;
    @@ -1253,6 +1295,8 @@ long do_fork(unsigned long clone_flags,
    if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
    ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
    }
    +
    + fork_connector(current->pid, p->pid);
    } else {
    free_pidmap(pid);
    pid = PTR_ERR(p);

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-04-06 13:30    [W:0.036 / U:121.880 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site