From 33a30ed4bdccd95ed84a1a20c1fef8ac89788ce5 Mon Sep 17 00:00:00 2001 From: Vasiliy Kulikov Date: Wed, 3 Aug 2011 22:26:55 +0400 Subject: shm: fix wrong tests Commit 4c677e2eefdb ("shm: optimize locking and ipc_namespace getting") introduced a copy-paste bug. Due to the bug cycle optimizations were disabled. Signed-off-by: Vasiliy Kulikov Signed-off-by: Linus Torvalds --- ipc/shm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index 9fb044f3b34..7efff043ffb 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -294,7 +294,7 @@ static int shm_try_destroy_orphaned(int id, void *p, void *data) void shm_destroy_orphaned(struct ipc_namespace *ns) { down_write(&shm_ids(ns).rw_mutex); - if (&shm_ids(ns).in_use) + if (shm_ids(ns).in_use) idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns); up_write(&shm_ids(ns).rw_mutex); } @@ -306,7 +306,7 @@ void exit_shm(struct task_struct *task) /* Destroy all already created segments, but not mapped yet */ down_write(&shm_ids(ns).rw_mutex); - if (&shm_ids(ns).in_use) + if (shm_ids(ns).in_use) idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns); up_write(&shm_ids(ns).rw_mutex); } -- cgit v1.2.3-70-g09d2 From 298507d4d2cff2248e84afcf646b697301294442 Mon Sep 17 00:00:00 2001 From: Vasiliy Kulikov Date: Wed, 3 Aug 2011 22:28:26 +0400 Subject: shm: optimize exit_shm() We may optimistically check .in_use == 0 without holding the rw_mutex: it's the common case, and if it's zero, there certainly won't be any segments associated with us. After taking the lock, the idr_for_each() will do the right thing, so we could now drop the re-check inside the lock without any real cost. But it won't hurt. Signed-off-by: Vasiliy Kulikov Signed-off-by: Linus Torvalds --- ipc/shm.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index 7efff043ffb..b5bae9d945b 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -304,6 +304,9 @@ void exit_shm(struct task_struct *task) { struct ipc_namespace *ns = task->nsproxy->ipc_ns; + if (shm_ids(ns).in_use == 0) + return; + /* Destroy all already created segments, but not mapped yet */ down_write(&shm_ids(ns).rw_mutex); if (shm_ids(ns).in_use) -- cgit v1.2.3-70-g09d2 From 140d0b2108faebc77c6523296e211e509cb9f5f9 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 4 Aug 2011 19:35:59 -1000 Subject: Do 'shm_init_ns()' in an early pure_initcall This isn't really critical any more, since other patches (commit 298507d4d2cf: "shm: optimize exit_shm()") have caused us to not actually need to touch the rw_mutex unless there are actual shm segments associated with the namespace, but we really should do tne shm_init_ns() earlier than we do now. This, together with commit 288d5abec831 ("Boot up with usermodehelper disabled") will mean that we really do initialize the initial ipc namespace data structure before we run any tasks. Tested-by: Marc Zyngier Signed-off-by: Linus Torvalds --- ipc/shm.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index b5bae9d945b..02ecf2c078f 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -105,9 +105,16 @@ void shm_exit_ns(struct ipc_namespace *ns) } #endif -void __init shm_init (void) +static int __init ipc_ns_init(void) { shm_init_ns(&init_ipc_ns); + return 0; +} + +pure_initcall(ipc_ns_init); + +void __init shm_init (void) +{ ipc_init_proc_interface("sysvipc/shm", #if BITS_PER_LONG <= 32 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n", -- cgit v1.2.3-70-g09d2