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Subject[PATCH] pids: introduce find_get_task_by_vpid helper
Date
There are several functions that do find_task_by_vpid() followed by
get_task_struct(). We can use a helper function instead.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
include/linux/sched.h | 5 +++++
kernel/futex.c | 7 +------
kernel/pid.c | 13 +++++++++++++
kernel/ptrace.c | 6 +-----
kernel/taskstats.c | 6 +-----
mm/process_vm_access.c | 6 +-----
6 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 26a7df4e558c..4c3af5255fcf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1484,6 +1484,11 @@ static inline struct thread_info *task_thread_info(struct task_struct *task)
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);

+/*
+ * find a task by its virtual pid and get the task struct
+ */
+extern struct task_struct *find_get_task_by_vpid(pid_t nr);
+
extern int wake_up_state(struct task_struct *tsk, unsigned int state);
extern int wake_up_process(struct task_struct *tsk);
extern void wake_up_new_task(struct task_struct *tsk);
diff --git a/kernel/futex.c b/kernel/futex.c
index 0518a0bfc746..6446aa9f2288 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -870,12 +870,7 @@ static struct task_struct *futex_find_get_task(pid_t pid)
{
struct task_struct *p;

- rcu_read_lock();
- p = find_task_by_vpid(pid);
- if (p)
- get_task_struct(p);
-
- rcu_read_unlock();
+ p = find_get_task_by_vpid(pid);

return p;
}
diff --git a/kernel/pid.c b/kernel/pid.c
index 020dedbdf066..ead086b0ef8e 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -462,6 +462,19 @@ struct task_struct *find_task_by_vpid(pid_t vnr)
return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
}

+struct task_struct *find_get_task_by_vpid(pid_t nr)
+{
+ struct task_struct *task;
+
+ rcu_read_lock();
+ task = find_task_by_vpid(nr);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ return task;
+}
+
struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
{
struct pid *pid;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 84b1367935e4..91efc97674ce 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1103,11 +1103,7 @@ static struct task_struct *ptrace_get_task_struct(pid_t pid)
{
struct task_struct *child;

- rcu_read_lock();
- child = find_task_by_vpid(pid);
- if (child)
- get_task_struct(child);
- rcu_read_unlock();
+ child = find_get_task_by_vpid(pid);

if (!child)
return ERR_PTR(-ESRCH);
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 4559e914452b..4e62a4a8fa91 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -194,11 +194,7 @@ static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
{
struct task_struct *tsk;

- rcu_read_lock();
- tsk = find_task_by_vpid(pid);
- if (tsk)
- get_task_struct(tsk);
- rcu_read_unlock();
+ tsk = find_get_task_by_vpid(pid);
if (!tsk)
return -ESRCH;
fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 8973cd231ece..16424b9ae424 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -197,11 +197,7 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
}

/* Get process information */
- rcu_read_lock();
- task = find_task_by_vpid(pid);
- if (task)
- get_task_struct(task);
- rcu_read_unlock();
+ task = find_get_task_by_vpid(pid);
if (!task) {
rc = -ESRCH;
goto free_proc_pages;
--
2.7.4
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