Deprecate find_task_by_pid()

There are some places that are known to operate on tasks' global pids only: * the rest_init() call (called on boot) * the kgdb's getthread * the create_kthread() (since the kthread is run in init ns) So use the find_task_by_pid_ns(..., &init_pid_ns) there and schedule the find_task_by_pid for removal. [[email protected]: Fix warning in kernel/pid.c] Signed-off-by: Pavel Emelyanov <[email protected]> Cc: "Eric W. Biederman" <[email protected]> Signed-off-by: Sukadev Bhattiprolu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
Chm · Apr 30, 2008 · 5cd2045 · 5cd2045
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commit 5cd2045
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Showing 5 changed files with 24 additions and 9 deletions.
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
@@ -138,6 +138,24 @@ Who:	Kay Sievers <[email protected]>
 
 ---------------------------
 
+What:	find_task_by_pid
+When:	2.6.26
+Why:	With pid namespaces, calling this funciton will return the
+	wrong task when called from inside a namespace.
+
+	The best way to save a task pid and find a task by this
+	pid later, is to find this task's struct pid pointer (or get
+	it directly from the task) and call pid_task() later.
+
+	If someone really needs to get a task by its pid_t, then
+	he most likely needs the find_task_by_vpid() to get the
+	task from the same namespace as the current task is in, but
+	this may be not so in general.
+
+Who:	Pavel Emelyanov <[email protected]>
+
+---------------------------
+
 What:	ACPI procfs interface
 When:	July 2008
 Why:	ACPI sysfs conversion should be finished by January 2008.

diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -1677,7 +1677,10 @@ extern struct pid_namespace init_pid_ns;
 extern struct task_struct *find_task_by_pid_type_ns(int type, int pid,
 		struct pid_namespace *ns);
 
-extern struct task_struct *find_task_by_pid(pid_t nr);
+static inline struct task_struct *__deprecated find_task_by_pid(pid_t nr)
+{
+	return find_task_by_pid_type_ns(PIDTYPE_PID, nr, &init_pid_ns);
+}
 extern struct task_struct *find_task_by_vpid(pid_t nr);
 extern struct task_struct *find_task_by_pid_ns(pid_t nr,
 		struct pid_namespace *ns);

diff --git a/init/main.c b/init/main.c
@@ -459,7 +459,7 @@ static void noinline __init_refok rest_init(void)
 	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 	numa_default_policy();
 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
-	kthreadd_task = find_task_by_pid(pid);
+	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 	unlock_kernel();
 
 	/*

diff --git a/kernel/kthread.c b/kernel/kthread.c
@@ -98,7 +98,7 @@ static void create_kthread(struct kthread_create_info *create)
 		struct sched_param param = { .sched_priority = 0 };
 		wait_for_completion(&create->started);
 		read_lock(&tasklist_lock);
-		create->result = find_task_by_pid(pid);
+		create->result = find_task_by_pid_ns(pid, &init_pid_ns);
 		read_unlock(&tasklist_lock);
 		/*
 		 * root may have changed our (kthreadd's) priority or CPU mask.

diff --git a/kernel/pid.c b/kernel/pid.c
@@ -381,12 +381,6 @@ struct task_struct *find_task_by_pid_type_ns(int type, int nr,
 
 EXPORT_SYMBOL(find_task_by_pid_type_ns);
 
-struct task_struct *find_task_by_pid(pid_t nr)
-{
-	return find_task_by_pid_type_ns(PIDTYPE_PID, nr, &init_pid_ns);
-}
-EXPORT_SYMBOL(find_task_by_pid);
-
 struct task_struct *find_task_by_vpid(pid_t vnr)
 {
 	return find_task_by_pid_type_ns(PIDTYPE_PID, vnr,