Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754384AbYLILbw (ORCPT ); Tue, 9 Dec 2008 06:31:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753869AbYLILbi (ORCPT ); Tue, 9 Dec 2008 06:31:38 -0500 Received: from ti-out-0910.google.com ([209.85.142.188]:6457 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753549AbYLILbg (ORCPT ); Tue, 9 Dec 2008 06:31:36 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=InoeLfEbpJeAq/TgHWLQkqPXIyse1SC90mwFuELlbuMqVrDoJj1/IxmEDc6H9HNFmP WEZpYLmu+tdOtUeU5C2jUgrU5md3se2RVBrW9IxjHmbkaQiWIF4eyo6YGJZWxH+5rfgB xqc/qJYKLYOJ7f2OnIxXYa/ZZ2WQ8Mw56RMdM= From: crquan@gmail.com To: dm-devel@redhat.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH] dm-target.c: simplify target_type to avoid kmalloc Date: Tue, 9 Dec 2008 19:32:35 +0800 Message-Id: <1228822355-12674-1-git-send-email-crquan@gmail.com> X-Mailer: git-send-email 1.6.0.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5182 Lines: 236 From: Cheng Renquan Move the list_head from tt_internal into struct target_type embedded, The struct tt_internal is totally unneeded, and the kmalloc is avoided, block of memory copy is also avoided, like the original: - ti->tt = *t; the function of tt_internal's use field is replaced by the module's reference count. The only defect is that dm_register_target users cannot use const target_type anymore. Signed-off-by: Cheng Renquan --- I have simply tested it, that seems work well till now. I found multi places in device-mapper code that kmalloc and vmalloc are over used, if this would be applied, I want to start a series of dm patches to improve them. drivers/md/dm-target.c | 122 +++++++++++++--------------------------- include/linux/device-mapper.h | 3 + 2 files changed, 43 insertions(+), 82 deletions(-) diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c index 835cf95..54a4ae0 100644 --- a/drivers/md/dm-target.c +++ b/drivers/md/dm-target.c @@ -14,142 +14,100 @@ #define DM_MSG_PREFIX "target" -struct tt_internal { - struct target_type tt; - - struct list_head list; - long use; -}; - static LIST_HEAD(_targets); static DECLARE_RWSEM(_lock); -#define DM_MOD_NAME_SIZE 32 - -static inline struct tt_internal *__find_target_type(const char *name) +static inline struct target_type *__find_target_type(const char *name) { - struct tt_internal *ti; + struct target_type *tt; - list_for_each_entry (ti, &_targets, list) - if (!strcmp(name, ti->tt.name)) - return ti; + list_for_each_entry (tt, &_targets, list) + if (!strcmp(name, tt->name)) + return tt; return NULL; } -static struct tt_internal *get_target_type(const char *name) +static struct target_type *get_target_type(const char *name) { - struct tt_internal *ti; + struct target_type *tt; down_read(&_lock); - - ti = __find_target_type(name); - if (ti) { - if ((ti->use == 0) && !try_module_get(ti->tt.module)) - ti = NULL; - else - ti->use++; - } - + tt = __find_target_type(name); + if (tt) + try_module_get(tt->module); up_read(&_lock); - return ti; -} -static void load_module(const char *name) -{ - request_module("dm-%s", name); + return tt; } struct target_type *dm_get_target_type(const char *name) { - struct tt_internal *ti = get_target_type(name); + struct target_type *tt = get_target_type(name); - if (!ti) { - load_module(name); - ti = get_target_type(name); + if (!tt) { + request_module("dm-%s", name); + tt = get_target_type(name); } - return ti ? &ti->tt : NULL; + return tt; } -void dm_put_target_type(struct target_type *t) +void dm_put_target_type(struct target_type *tt) { - struct tt_internal *ti = (struct tt_internal *) t; - down_read(&_lock); - if (--ti->use == 0) - module_put(ti->tt.module); - - BUG_ON(ti->use < 0); + module_put(tt->module); up_read(&_lock); - - return; } -static struct tt_internal *alloc_target(struct target_type *t) -{ - struct tt_internal *ti = kzalloc(sizeof(*ti), GFP_KERNEL); - - if (ti) - ti->tt = *t; - - return ti; -} - - int dm_target_iterate(void (*iter_func)(struct target_type *tt, void *param), void *param) { - struct tt_internal *ti; + struct target_type *tt; down_read(&_lock); - list_for_each_entry (ti, &_targets, list) - iter_func(&ti->tt, param); + list_for_each_entry (tt, &_targets, list) + iter_func(tt, param); up_read(&_lock); return 0; } -int dm_register_target(struct target_type *t) +int dm_register_target(struct target_type *tt) { - int rv = 0; - struct tt_internal *ti = alloc_target(t); - - if (!ti) - return -ENOMEM; + int ret = 0; down_write(&_lock); - if (__find_target_type(t->name)) - rv = -EEXIST; + if (__find_target_type(tt->name)) + ret = -EEXIST; else - list_add(&ti->list, &_targets); - + list_add(&tt->list, &_targets); up_write(&_lock); - if (rv) - kfree(ti); - return rv; + + return ret; } -int dm_unregister_target(struct target_type *t) +int dm_unregister_target(struct target_type *tt) { - struct tt_internal *ti; + int ret = 0; down_write(&_lock); - if (!(ti = __find_target_type(t->name))) { - up_write(&_lock); - return -EINVAL; + if (!__find_target_type(tt->name)) { + ret = -EINVAL; + goto out; } - if (ti->use) { - up_write(&_lock); - return -ETXTBSY; + if (tt->module && module_refcount(tt->module)) { + ret = -ETXTBSY; + goto out; } - list_del(&ti->list); - kfree(ti); + list_del(&tt->list); + out: up_write(&_lock); - return 0; + + return ret; } /* diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index c17fd33..8bcc7f5 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -117,6 +117,9 @@ struct target_type { dm_message_fn message; dm_ioctl_fn ioctl; dm_merge_fn merge; + + /* for internal use only */ + struct list_head list; }; struct io_restrictions { -- 1.6.0.4.762.gbd861 -- 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/