[PATCH v2 -mm 1/2] rename is_single_threaded(task) to current_is_single_threaded(void)

Oleg Nesterov
2009-07-10T01:52:18Z

(on top of rework-fix-is_single_threaded.patch)

- is_single_threaded(task) is not safe unless task == current,
we can't use task->signal or task->mm.

- it doesn't make sense unless task == current, the task can
fork right after the check.

Rename it to current_is_single_threaded() and kill the argument.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
---

include/linux/sched.h | 2 +-
lib/is_single_threaded.c | 3 ++-
security/selinux/hooks.c | 2 +-
security/keys/process_keys.c | 2 +-
4 files changed, 5 insertions(+), 4 deletions(-)

--- WAIT/include/linux/sched.h~ISS_1_RENAME 2009-07-01 20:20:57.000000000 +0200
+++ WAIT/include/linux/sched.h 2009-07-09 22:14:21.000000000 +0200
@@ -2055,7 +2055,7 @@ static inline unsigned long wait_task_in
#define for_each_process(p) \
for (p = &init_task ; (p = next_task(p)) != &init_task ; )

-extern bool is_single_threaded(struct task_struct *);
+extern bool current_is_single_threaded(void);

/*
* Careful: do_each_thread/while_each_thread is a double loop so
--- WAIT/lib/is_single_threaded.c~ISS_1_RENAME 2009-07-09 19:43:27.000000000 +0200
+++ WAIT/lib/is_single_threaded.c 2009-07-09 22:16:29.000000000 +0200
@@ -15,8 +15,9 @@
/*
* Returns true if the task does not share ->mm with another thread/process.
*/
-bool is_single_threaded(struct task_struct *task)
+bool current_is_single_threaded(void)
{
+ struct task_struct *task = current;
struct mm_struct *mm = task->mm;
struct task_struct *p, *t;
bool ret;
--- WAIT/security/selinux/hooks.c~ISS_1_RENAME 2009-07-03 11:15:08.000000000 +0200
+++ WAIT/security/selinux/hooks.c 2009-07-09 22:17:58.000000000 +0200
@@ -5182,7 +5182,7 @@ static int selinux_setprocattr(struct ta

/* Only allow single threaded processes to change context */
error = -EPERM;
- if (!is_single_threaded(p)) {
+ if (!current_is_single_threaded()) {
error = security_bounded_transition(tsec->sid, sid);
if (error)
goto abort_change;
--- WAIT/security/keys/process_keys.c~ISS_1_RENAME 2009-04-06 00:03:42.000000000 +0200
+++ WAIT/security/keys/process_keys.c 2009-07-09 22:18:31.000000000 +0200
@@ -702,7 +702,7 @@ long join_session_keyring(const char *na
/* only permit this if there's a single thread in the thread group -
* this avoids us having to adjust the creds on all threads and risking
* ENOMEM */
- if (!is_single_threaded(current))
+ if (!current_is_single_threaded())
return -EMLINK;

new = prepare_creds();