From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756114AbXIZDMr (ORCPT ); Tue, 25 Sep 2007 23:12:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751830AbXIZDMj (ORCPT ); Tue, 25 Sep 2007 23:12:39 -0400 Received: from smtp-out.google.com ([216.239.33.17]:41568 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751799AbXIZDMi (ORCPT ); Tue, 25 Sep 2007 23:12:38 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:user-agent:mime-version:to:cc: subject:content-type:content-transfer-encoding; b=YikygbiwpyYsaoBW7NrYn9ZHL8M4e37aaMTpz09eperIfipBslrFK0b9P9CKamWae FIFQ2BmpcKBlYMer/t3Rg== Message-ID: <46F9CE16.9080302@google.com> Date: Tue, 25 Sep 2007 20:12:22 -0700 From: Paul Menage User-Agent: Thunderbird 1.5.0.12 (X11/20070604) MIME-Version: 1.0 To: akpm@linux-foundation.org, containers@lists.linux-foundation.org CC: linux-kernel@vger.kernel.org Subject: [PATCH] Add cgroup write_uint() helper method Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Add write_uint() helper method for cgroup subsystems This helper is analagous to the read_uint() helper method for reporting u64 values to userspace. It's designed to reduce the amount of boilerplate requierd for creating new cgroup subsystems. Signed-off-by: Paul Menage --- include/linux/cgroup.h | 8 ++++++++ kernel/cgroup.c | 42 ++++++++++++++++++++++++++++++++++++++---- 2 files changed, 46 insertions(+), 4 deletions(-) Index: container-2.6.23-rc8-mm1/include/linux/cgroup.h =================================================================== --- container-2.6.23-rc8-mm1.orig/include/linux/cgroup.h +++ container-2.6.23-rc8-mm1/include/linux/cgroup.h @@ -196,6 +196,14 @@ struct cftype { ssize_t (*write) (struct cgroup *cont, struct cftype *cft, struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos); + + /* + * write_uint() is a shortcut for the common case of accepting + * a single integer (as parsed by simple_strtoull) from + * userspace. Use in place of write(); return 0 or error. + */ + int (*write_uint) (struct cgroup *cont, struct cftype *cft, u64 val); + int (*release) (struct inode *inode, struct file *file); }; Index: container-2.6.23-rc8-mm1/kernel/cgroup.c =================================================================== --- container-2.6.23-rc8-mm1.orig/kernel/cgroup.c +++ container-2.6.23-rc8-mm1/kernel/cgroup.c @@ -1274,6 +1274,39 @@ enum cgroup_filetype { FILE_RELEASE_AGENT, }; +static ssize_t cgroup_write_uint(struct cgroup *cont, struct cftype *cft, + struct file *file, + const char __user *userbuf, + size_t nbytes, loff_t *unused_ppos) +{ + char buffer[64]; + int retval = 0; + u64 val; + char *end; + + if (!nbytes) + return -EINVAL; + if (nbytes >= sizeof(buffer)) + return -E2BIG; + if (copy_from_user(buffer, userbuf, nbytes)) + return -EFAULT; + + buffer[nbytes] = 0; /* nul-terminate */ + + /* strip newline if necessary */ + if (nbytes && (buffer[nbytes-1] == '\n')) + buffer[nbytes-1] = 0; + val = simple_strtoull(buffer, &end, 0); + if (*end) + return -EINVAL; + + /* Pass to subsystem */ + retval = cft->write_uint(cont, cft, val); + if (!retval) + retval = nbytes; + return retval; +} + static ssize_t cgroup_common_file_write(struct cgroup *cont, struct cftype *cft, struct file *file, @@ -1357,10 +1390,11 @@ static ssize_t cgroup_file_write(struct if (!cft) return -ENODEV; - if (!cft->write) - return -EINVAL; - - return cft->write(cont, cft, file, buf, nbytes, ppos); + if (cft->write) + return cft->write(cont, cft, file, buf, nbytes, ppos); + if (cft->write_uint) + return cgroup_write_uint(cont, cft, file, buf, nbytes, ppos); + return -EINVAL; } static ssize_t cgroup_read_uint(struct cgroup *cont, struct cftype *cft,