add watch_head to task_struct.
This is used by /proc/<pid> readdir() routine.
pointer from /proc (which traverse task_list) is moved to next_task()
if target task is removed.
Note: next_task() in release_task() never return stale task struct.
Signed-Off-By: KAMEZAWA Hiroyuki <[email protected]>
include/linux/init_task.h | 2 ++
include/linux/sched.h | 4 +++-
kernel/exit.c | 7 ++++++-
kernel/fork.c | 3 +++
4 files changed, 14 insertions(+), 2 deletions(-)
Index: linux-2.6.18-rc4/include/linux/sched.h
===================================================================
--- linux-2.6.18-rc4.orig/include/linux/sched.h
+++ linux-2.6.18-rc4/include/linux/sched.h
@@ -80,6 +80,7 @@ struct sched_param {
#include <linux/resource.h>
#include <linux/timer.h>
#include <linux/hrtimer.h>
+#include <linux/watch_head.h>
#include <asm/processor.h>
@@ -988,7 +989,8 @@ struct task_struct {
atomic_t fs_excl; /* holding fs exclusive resources */
struct rcu_head rcu;
-
+ /* used by /proc/<pid> */
+ struct watch_head watch;
/*
* cache last used pipe for splice
*/
Index: linux-2.6.18-rc4/kernel/fork.c
===================================================================
--- linux-2.6.18-rc4.orig/kernel/fork.c
+++ linux-2.6.18-rc4/kernel/fork.c
@@ -45,6 +45,7 @@
#include <linux/cn_proc.h>
#include <linux/delayacct.h>
#include <linux/taskstats_kern.h>
+#include <linux/watch_head.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -1154,6 +1155,7 @@ static struct task_struct *copy_process(
INIT_LIST_HEAD(&p->thread_group);
INIT_LIST_HEAD(&p->ptrace_children);
INIT_LIST_HEAD(&p->ptrace_list);
+ init_watch(&p->watch);
/* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags);
@@ -1241,6 +1243,7 @@ static struct task_struct *copy_process(
__get_cpu_var(process_counts)++;
}
attach_pid(p, PIDTYPE_PID, p->pid);
+ make_watch_ready(&p->watch);
nr_threads++;
}
Index: linux-2.6.18-rc4/include/linux/init_task.h
===================================================================
--- linux-2.6.18-rc4.orig/include/linux/init_task.h
+++ linux-2.6.18-rc4/include/linux/init_task.h
@@ -5,6 +5,7 @@
#include <linux/rcupdate.h>
#include <linux/irqflags.h>
#include <linux/lockdep.h>
+#include <linux/watch_head.h>
#define INIT_FDTABLE \
{ \
@@ -128,6 +129,7 @@ extern struct group_info init_groups;
.pi_lock = SPIN_LOCK_UNLOCKED, \
INIT_TRACE_IRQFLAGS \
INIT_LOCKDEP \
+ .watch = WATCH_HEAD_INIT(tsk.watch), \
}
Index: linux-2.6.18-rc4/kernel/exit.c
===================================================================
--- linux-2.6.18-rc4.orig/kernel/exit.c
+++ linux-2.6.18-rc4/kernel/exit.c
@@ -38,6 +38,7 @@
#include <linux/pipe_fs_i.h>
#include <linux/audit.h> /* for audit_free() */
#include <linux/resource.h>
+#include <linux/watch_head.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -136,13 +137,17 @@ static void delayed_put_task_struct(stru
void release_task(struct task_struct * p)
{
- struct task_struct *leader;
+ struct task_struct *leader, *next;
int zap_leader;
repeat:
atomic_dec(&p->user->processes);
write_lock_irq(&tasklist_lock);
ptrace_unlink(p);
BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
+
+ /* move pointer from /proc to next task */
+ next = next_task(p);
+ move_watcher(&p->watch, &next->watch);
__exit_signal(p);
/*
-
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