Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161386AbWHDTxi (ORCPT ); Fri, 4 Aug 2006 15:53:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161388AbWHDTxh (ORCPT ); Fri, 4 Aug 2006 15:53:37 -0400 Received: from mx1.redhat.com ([66.187.233.31]:4764 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1161386AbWHDTxh (ORCPT ); Fri, 4 Aug 2006 15:53:37 -0400 Subject: Re: [PATCH] module interface improvement for kprobes From: David Smith To: "Randy.Dunlap" Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, prasanna@in.ibm.com, ananth@in.ibm.com, anil.s.keshavamurthy@intel.com, davem@davemloft.net In-Reply-To: <20060804090018.0bd4020d.rdunlap@xenotime.net> References: <1154704652.15967.7.camel@dhcp-2.hsv.redhat.com> <20060804090018.0bd4020d.rdunlap@xenotime.net> Content-Type: text/plain Date: Fri, 04 Aug 2006 14:51:01 -0500 Message-Id: <1154721061.15967.31.camel@dhcp-2.hsv.redhat.com> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-27) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2900 Lines: 93 Randy, Thanks for looking at this. I implemented your suggestions and also changed EXPORT_SYMBOL to EXPORT_SYMBOL_GPL. On Fri, 2006-08-04 at 09:00 -0700, Randy.Dunlap wrote: > On Fri, 04 Aug 2006 10:17:32 -0500 David Smith wrote: > > > When inserting a kprobes probe into a loadable module, there isn't a way > > for the kprobes module to get a module reference (in order to find the > > base address of the module among perhaps other things). > > > > A kprobes probe needs the base address of the module in order to > > "relocate" the addresses of probe points (since the load address of the > > module can change from run to run of the kprobe). > > > > I've added a new function, module_get_byname(), that looks up a module > > by name and returns the module reference. Note that module_get_byname() > > also increments the module reference count. It does this so that the > > module won't be unloaded between the time that module_get_byname() is > > called and register_kprobe() is called. ... Signed off by David Smith ---- diff --git a/include/linux/module.h b/include/linux/module.h index 0dfb794..9953a38 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -374,6 +374,8 @@ extern void __module_put_and_exit(struct __attribute__((noreturn)); #define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code); +int module_get_byname(const char *mod_name, struct module **mod); + #ifdef CONFIG_MODULE_UNLOAD unsigned int module_refcount(struct module *mod); void __symbol_put(const char *symbol); @@ -549,6 +551,11 @@ static inline int is_exported(const char return 0; } +static inline int module_get_byname(const char *mod_name, struct module **mod) +{ + return 1; +} + static inline int register_module_notifier(struct notifier_block * nb) { /* no events will happen anyway, so this can always succeed */ diff --git a/kernel/module.c b/kernel/module.c index 2a19cd4..473cc0b 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -291,7 +291,27 @@ static struct module *find_module(const } return NULL; } + +int module_get_byname(const char *mod_name, struct module **mod) +{ + *mod = NULL; + /* We must hold module_mutex before calling find_module(). */ + if (mutex_lock_interruptible(&module_mutex) != 0) + return -EINTR; + + *mod = find_module(mod_name); + mutex_unlock(&module_mutex); + if (*mod) { + if (!strong_try_module_get(*mod)) { + *mod = NULL; + return -EINVAL; + } + } + return 0; +} +EXPORT_SYMBOL_GPL(module_get_byname); + #ifdef CONFIG_SMP /* Number of blocks used and allocated. */ static unsigned int pcpu_num_used, pcpu_num_allocated; - 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/