Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753645Ab0G3X6c (ORCPT ); Fri, 30 Jul 2010 19:58:32 -0400 Received: from SMTP.ANDREW.CMU.EDU ([128.2.11.95]:47390 "EHLO smtp.andrew.cmu.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753493Ab0G3X63 (ORCPT ); Fri, 30 Jul 2010 19:58:29 -0400 Date: Fri, 30 Jul 2010 19:57:54 -0400 From: Ben Blum To: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org Cc: akpm@linux-foundation.org, bblum@andrew.cmu.edu, ebiederm@xmission.com, lizf@cn.fujitsu.com, matthltc@us.ibm.com, menage@google.com, oleg@redhat.com Subject: [PATCH v4 1/2] cgroups: read-write lock CLONE_THREAD forking per threadgroup Message-ID: <20100730235754.GB22644@ghc17.ghc.andrew.cmu.edu> References: <20100730235649.GA22644@ghc17.ghc.andrew.cmu.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="cgroup-threadgroup-fork-lock.patch" In-Reply-To: <20100730235649.GA22644@ghc17.ghc.andrew.cmu.edu> User-Agent: Mutt/1.5.20 (2009-06-14) X-PMX-Version: 5.5.9.388399, Antispam-Engine: 2.7.2.376379, Antispam-Data: 2010.7.30.234515 X-SMTP-Spam-Clean: 8% ( BODY_SIZE_3000_3999 0, BODY_SIZE_5000_LESS 0, BODY_SIZE_7000_LESS 0, __CD 0, __CT 0, __CT_TEXT_PLAIN 0, __HAS_MSGID 0, __MIME_TEXT_ONLY 0, __MIME_VERSION 0, __SANE_MSGID 0, __TO_MALFORMED_2 0, __TO_NO_NAME 0, __URI_NO_PATH 0, __URI_NO_WWW 0, __USER_AGENT 0) X-SMTP-Spam-Score: 8% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3932 Lines: 120 Adds functionality to read/write lock CLONE_THREAD fork()ing per-threadgroup From: Ben Blum This patch adds an rwsem that lives in a threadgroup's signal_struct that's taken for reading in the fork path, under CONFIG_CGROUPS. If another part of the kernel later wants to use such a locking mechanism, the CONFIG_CGROUPS ifdefs should be changed to a higher-up flag that CGROUPS and the other system would both depend on. This is a pre-patch for cgroups-procs-write.patch. Signed-off-by: Ben Blum --- include/linux/init_task.h | 9 +++++++++ include/linux/sched.h | 10 ++++++++++ kernel/fork.c | 16 ++++++++++++++++ 3 files changed, 35 insertions(+), 0 deletions(-) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 1f43fa5..ca46711 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -15,6 +15,14 @@ extern struct files_struct init_files; extern struct fs_struct init_fs; +#ifdef CONFIG_CGROUPS +#define INIT_THREADGROUP_FORK_LOCK(sig) \ + .threadgroup_fork_lock = \ + __RWSEM_INITIALIZER(sig.threadgroup_fork_lock), +#else +#define INIT_THREADGROUP_FORK_LOCK(sig) +#endif + #define INIT_SIGNALS(sig) { \ .nr_threads = 1, \ .wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\ @@ -29,6 +37,7 @@ extern struct fs_struct init_fs; .running = 0, \ .lock = __SPIN_LOCK_UNLOCKED(sig.cputimer.lock), \ }, \ + INIT_THREADGROUP_FORK_LOCK(sig) \ } extern struct nsproxy init_nsproxy; diff --git a/include/linux/sched.h b/include/linux/sched.h index ae69716..82b0bcf 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -619,6 +619,16 @@ struct signal_struct { unsigned audit_tty; struct tty_audit_buf *tty_audit_buf; #endif +#ifdef CONFIG_CGROUPS + /* + * The threadgroup_fork_lock prevents threads from forking with + * CLONE_THREAD while held for writing. Use this for fork-sensitive + * threadgroup-wide operations. It's taken for reading in fork.c in + * copy_process(). + * Currently only needed write-side by cgroups. + */ + struct rw_semaphore threadgroup_fork_lock; +#endif int oom_adj; /* OOM kill score adjustment (bit shift) */ }; diff --git a/kernel/fork.c b/kernel/fork.c index a82a65c..a9bce89 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -898,6 +898,10 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) tty_audit_fork(sig); +#ifdef CONFIG_CGROUPS + init_rwsem(&sig->threadgroup_fork_lock); +#endif + sig->oom_adj = current->signal->oom_adj; return 0; @@ -1076,6 +1080,10 @@ static struct task_struct *copy_process(unsigned long clone_flags, monotonic_to_bootbased(&p->real_start_time); p->io_context = NULL; p->audit_context = NULL; +#ifdef CONFIG_CGROUPS + if (clone_flags & CLONE_THREAD) + down_read(¤t->signal->threadgroup_fork_lock); +#endif cgroup_fork(p); #ifdef CONFIG_NUMA p->mempolicy = mpol_dup(p->mempolicy); @@ -1283,6 +1291,10 @@ static struct task_struct *copy_process(unsigned long clone_flags, write_unlock_irq(&tasklist_lock); proc_fork_connector(p); cgroup_post_fork(p); +#ifdef CONFIG_CGROUPS + if (clone_flags & CLONE_THREAD) + up_read(¤t->signal->threadgroup_fork_lock); +#endif perf_event_fork(p); return p; @@ -1316,6 +1328,10 @@ bad_fork_cleanup_policy: mpol_put(p->mempolicy); bad_fork_cleanup_cgroup: #endif +#ifdef CONFIG_CGROUPS + if (clone_flags & CLONE_THREAD) + up_read(¤t->signal->threadgroup_fork_lock); +#endif cgroup_exit(p, cgroup_callbacks_done); delayacct_tsk_free(p); module_put(task_thread_info(p)->exec_domain->module); -- 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/