Subject: [merged] kernel-forkc-copy_process-consolidate-the-lockless-clone_thread-checks.patch removed from -mm tree
To: oleg@xxxxxxxxxx,dserrg@xxxxxxxxx,ebiederm@xxxxxxxxxxxx,mhocko@xxxxxxx,xemul@xxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 08 Jul 2013 12:36:11 -0700
The patch titled
Subject: kernel/fork.c:copy_process(): consolidate the lockless CLONE_THREAD checks
has been removed from the -mm tree. Its filename was
kernel-forkc-copy_process-consolidate-the-lockless-clone_thread-checks.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: kernel/fork.c:copy_process(): consolidate the lockless CLONE_THREAD checks
copy_process() does a lot of "chaotic" initializations and checks
CLONE_THREAD twice before it takes tasklist. In particular it sets
"p->group_leader = p" and then changes it again under tasklist if
!thread_group_leader(p).
This looks a bit confusing, lets create a single "if (CLONE_THREAD)" block
which initializes ->exit_signal, ->group_leader, and ->tgid.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Sergey Dyasly <dserrg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 33 ++++++++++++++++-----------------
1 file changed, 16 insertions(+), 17 deletions(-)
diff -puN kernel/fork.c~kernel-forkc-copy_process-consolidate-the-lockless-clone_thread-checks kernel/fork.c
--- a/kernel/fork.c~kernel-forkc-copy_process-consolidate-the-lockless-clone_thread-checks
+++ a/kernel/fork.c
@@ -1360,11 +1360,6 @@ static struct task_struct *copy_process(
goto bad_fork_cleanup_io;
}
- p->pid = pid_nr(pid);
- p->tgid = p->pid;
- if (clone_flags & CLONE_THREAD)
- p->tgid = current->tgid;
-
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
/*
* Clear TID on mm_release()?
@@ -1400,12 +1395,19 @@ static struct task_struct *copy_process(
clear_all_latency_tracing(p);
/* ok, now we should be set up.. */
- if (clone_flags & CLONE_THREAD)
+ p->pid = pid_nr(pid);
+ if (clone_flags & CLONE_THREAD) {
p->exit_signal = -1;
- else if (clone_flags & CLONE_PARENT)
- p->exit_signal = current->group_leader->exit_signal;
- else
- p->exit_signal = (clone_flags & CSIGNAL);
+ p->group_leader = current->group_leader;
+ p->tgid = current->tgid;
+ } else {
+ if (clone_flags & CLONE_PARENT)
+ p->exit_signal = current->group_leader->exit_signal;
+ else
+ p->exit_signal = (clone_flags & CSIGNAL);
+ p->group_leader = p;
+ p->tgid = p->pid;
+ }
p->pdeath_signal = 0;
p->exit_state = 0;
@@ -1414,15 +1416,13 @@ static struct task_struct *copy_process(
p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
p->dirty_paused_when = 0;
- /*
- * Ok, make it visible to the rest of the system.
- * We dont wake it up yet.
- */
- p->group_leader = p;
INIT_LIST_HEAD(&p->thread_group);
p->task_works = NULL;
- /* Need tasklist lock for parent etc handling! */
+ /*
+ * Make it visible to the rest of the system, but dont wake it up yet.
+ * Need tasklist lock for parent etc handling!
+ */
write_lock_irq(&tasklist_lock);
/* CLONE_PARENT re-uses the old parent */
@@ -1476,7 +1476,6 @@ static struct task_struct *copy_process(
current->signal->nr_threads++;
atomic_inc(¤t->signal->live);
atomic_inc(¤t->signal->sigcnt);
- p->group_leader = current->group_leader;
list_add_tail_rcu(&p->thread_group,
&p->group_leader->thread_group);
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
include-linux-schedh-dont-use-task-pid-tgid-in-same_thread_group-has_group_leader_pid.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
fput-task_work_add-can-fail-if-the-caller-has-passed-exit_task_work-fix.patch
fput-turn-list_head-delayed_fput_list-into-llist_head.patch
llist-fix-simplify-llist_add-and-llist_add_batch.patch
llist-llist_add-can-use-llist_add_batch.patch
vfree-dont-schedule-free_work-if-llist_add-returns-false.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch
ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch
ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch
ptrace-x86-introduce-ptrace_register_breakpoint.patch
ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch
ptrace-x86-cleanup-ptrace_set_debugreg.patch
ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch
ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch
signals-eventpoll-set-saved_sigmask-at-the-start.patch
move-exit_task_namespaces-outside-of-exit_notify-fix.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
