Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262756AbVBYQ6w (ORCPT ); Fri, 25 Feb 2005 11:58:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262754AbVBYQ6P (ORCPT ); Fri, 25 Feb 2005 11:58:15 -0500 Received: from rproxy.gmail.com ([64.233.170.202]:10337 "EHLO rproxy.gmail.com") by vger.kernel.org with ESMTP id S262741AbVBYQyZ (ORCPT ); Fri, 25 Feb 2005 11:54:25 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:references; b=utxWZgFynFOp4Bx17KYb4Rl+FEdKUVOnHGv1hFl6lHHexF1kT2fmvShZK+jfIVpGI5DxRwm+3r4G0oESXwakW8NPKdR2dqLZbBqq6nMlh3H4oTCWFHJny0bH3vYuDkdrirs55J6jfiDTXPiaAphJvqw0t9m0vWyVHvfUGeMD11w= Message-ID: <9cde8bff050225085479761ef4@mail.gmail.com> Date: Sat, 26 Feb 2005 01:54:24 +0900 From: aq Reply-To: aq To: Guillaume Thouvenin Subject: Re: [PATCH 2.6.11-rc4-mm1] connector: Add a fork connector Cc: Andrew Morton , lkml , Evgeniy Polyakov , elsa-devel , Jay Lan , Gerrit Huizenga , Erich Focht In-Reply-To: <1109240677.1738.196.camel@frecb000711.frec.bull.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit References: <1109240677.1738.196.camel@frecb000711.frec.bull.fr> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8933 Lines: 231 On Thu, 24 Feb 2005 11:24:37 +0100, Guillaume Thouvenin wrote: > This patch replaces the relay_fork module and it implements a fork > connector in the kernel/fork.c:do_fork() routine. It applies on a kernel > 2.6.11-rc4-mm1. The connector sends information about parent PID and > child PID over a netlink interface. It allows to several user space > applications to be informed when a fork occurs in the kernel. The main > drawback is that even if nobody listens, message is send. I don't know > how to avoid that. > > It is used by ELSA to manage group of processes in user space and can > be used by any other user space application that needs this kind of > information. > > I add a callback that turns on/off the fork connector. It's a very > simple mechanism and, as Evgeniy suggested, it may need a more complex > protocol. > > ChangeLog: > > - "fork_id" is now declared as a static const > - Replace snprintf() by scnprintf() > - Protect "seq" by a spin lock because the seq number can be > used by the daemon to check if all forks are intercepted > - "msg" send is now local > - Add a callback that turns on/off the fork connector. > - memset is only used to clear the msg->data part instead of all > message. > > Todo: > > - Test the performance impact with lmbench > - Improve the callback that turns on/off the fork connector > - Create a specific module to register the callback. > > Thanks to Andrew, Evgeniy and everyone for the comments, > Guillaume > > Signed-off-by: Guillaume Thouvenin > > --- > > drivers/connector/Kconfig | 11 ++++++++++ > drivers/connector/connector.c | 20 ++++++++++++++++++ > include/linux/connector.h | 3 ++ > kernel/fork.c | 45 ++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 79 insertions(+) > > diff -uprN -X dontdiff linux-2.6.11-rc4-mm1/drivers/connector/connector.c linux-2.6.11-rc4-mm1-cnfork/drivers/connector/connector.c > --- linux-2.6.11-rc4-mm1/drivers/connector/connector.c 2005-02-23 11:12:15.000000000 +0100 > +++ linux-2.6.11-rc4-mm1-cnfork/drivers/connector/connector.c 2005-02-24 10:21:59.000000000 +0100 > @@ -45,8 +45,10 @@ static DEFINE_SPINLOCK(notify_lock); > static LIST_HEAD(notify_list); > > static struct cn_dev cdev; > +static struct cb_id cn_fork_id = { CN_IDX_FORK, CN_VAL_FORK }; > > int cn_already_initialized = 0; > +int cn_fork_enable = 0; > > /* > * msg->seq and msg->ack are used to determine message genealogy. > @@ -467,6 +469,14 @@ static void cn_callback(void * data) > } > } > > +static void cn_fork_callback(void *data) > +{ > + if (cn_already_initialized) > + cn_fork_enable = cn_fork_enable ? 0 : 1; > + > + printk(KERN_NOTICE "cn_fork_enable is set to %i\n", cn_fork_enable); > +} > + > static int cn_init(void) > { > struct cn_dev *dev = &cdev; > @@ -498,6 +508,15 @@ static int cn_init(void) > return -EINVAL; > } > > + err = cn_add_callback(&cn_fork_id, "cn_fork", &cn_fork_callback); > + if (err) { > + cn_del_callback(&dev->id); > + cn_queue_free_dev(dev->cbdev); > + if (dev->nls->sk_socket) > + sock_release(dev->nls->sk_socket); > + return -EINVAL; > + } > + > cn_already_initialized = 1; > > return 0; > @@ -507,6 +526,7 @@ static void cn_fini(void) > { > struct cn_dev *dev = &cdev; > > + cn_del_callback(&cn_fork_id); > cn_del_callback(&dev->id); > cn_queue_free_dev(dev->cbdev); > if (dev->nls->sk_socket) > diff -uprN -X dontdiff linux-2.6.11-rc4-mm1/drivers/connector/Kconfig linux-2.6.11-rc4-mm1-cnfork/drivers/connector/Kconfig > --- linux-2.6.11-rc4-mm1/drivers/connector/Kconfig 2005-02-23 11:12:15.000000000 +0100 > +++ linux-2.6.11-rc4-mm1-cnfork/drivers/connector/Kconfig 2005-02-24 10:29:11.000000000 +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 > diff -uprN -X dontdiff linux-2.6.11-rc4-mm1/include/linux/connector.h linux-2.6.11-rc4-mm1-cnfork/include/linux/connector.h > --- linux-2.6.11-rc4-mm1/include/linux/connector.h 2005-02-23 11:12:17.000000000 +0100 > +++ linux-2.6.11-rc4-mm1-cnfork/include/linux/connector.h 2005-02-24 10:25:22.000000000 +0100 > @@ -28,6 +28,8 @@ > #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 > @@ -133,6 +135,7 @@ struct cn_dev > }; > > extern int cn_already_initialized; > +extern int cn_fork_enable; > > int cn_add_callback(struct cb_id *, char *, void (* callback)(void *)); > void cn_del_callback(struct cb_id *); > diff -uprN -X dontdiff linux-2.6.11-rc4-mm1/kernel/fork.c linux-2.6.11-rc4-mm1-cnfork/kernel/fork.c > --- linux-2.6.11-rc4-mm1/kernel/fork.c 2005-02-23 11:12:17.000000000 +0100 > +++ linux-2.6.11-rc4-mm1-cnfork/kernel/fork.c 2005-02-24 10:27:02.000000000 +0100 > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -63,6 +64,48 @@ 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 > + > +spinlock_t fork_cn_lock = SPIN_LOCK_UNLOCKED; > + > +static inline void fork_connector(pid_t parent, pid_t child) > +{ > + static const struct cb_id fork_id = { CN_IDX_FORK, CN_VAL_FORK }; > + static __u32 seq; /* used to test if message is lost */ > + > + if (cn_fork_enable) { > + struct cn_msg *msg; > + __u8 buffer[CN_FORK_MSG_SIZE]; > + > + msg = (struct cn_msg *)buffer; > + > + memcpy(&msg->id, &fork_id, sizeof(msg->id)); > + spin_lock(&fork_cn_lock); > + msg->seq = seq++; > + spin_unlock(&fork_cn_lock); > + msg->ack = 0; /* not used */ > + /* > + * size of data is the number of characters > + * printed plus one for the trailing '\0' > + */ > + /* just fill the data part with '\0' */ > + memset(msg->data, '\0', CN_FORK_INFO_SIZE); > + msg->len = scnprintf(msg->data, CN_FORK_INFO_SIZE-1, > + "%i %i", parent, child) + 1; > + > + cn_netlink_send(msg, CN_IDX_FORK); > + } > +} > +#else > +static inline void fork_connector(pid_t parent, pid_t child) > +{ > + return; > +} > +#endif > + > int nr_processes(void) > { > int cpu; > @@ -1238,6 +1281,8 @@ 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); Guillaume, I see that you are trying to discover if the kernel has CONFIG_FORK_CONNECTOR defined or not. In case CONFIG_FORK_CONNECTOR is not defined, you will call a "dummy" fork_connector (which just call "return"). But why you dont move the checking to where you call fork_connector? In this case, if CONFIG_FORK_CONNECTOR is not defined, nothing called, and of course you dont need a "dummy" fork_connector like in the above code. Just try something like this: +#ifdef CONFIG_FORK_CONNECTOR + + fork_connector(current->pid, p->pid); #endif regards, AQ - 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/