freezer: don't unnecessarily set PF_NOFREEZE explicitly

Some drivers set PF_NOFREEZE in their kthread functions which is
completely unnecessary and racy - some part of freezer code doesn't
consider cases where PF_NOFREEZE is set asynchronous to freezer
operations.

In general, there's no reason to allow setting PF_NOFREEZE explicitly.
Remove them and change the documentation to note that setting
PF_NOFREEZE directly isn't allowed.

-v2: Dropped change to twl4030-irq.c as it no longer uses PF_NOFREEZE.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: "Gustavo F. Padovan" <padovan@profusion.mobi>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: wwang <wei_wang@realsil.com.cn>

4 files changed, 1 insertions, 7 deletions

diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt
index 316c2ba187f4..587e0828053f 100644
--- a/Documentation/power/freezing-of-tasks.txt
+++ b/Documentation/power/freezing-of-tasks.txt
@@ -67,7 +67,7 @@ III. Which kernel threads are freezable?
 
 Kernel threads are not freezable by default.  However, a kernel thread may clear
 PF_NOFREEZE for itself by calling set_freezable() (the resetting of PF_NOFREEZE
-directly is strongly discouraged).  From this point it is regarded as freezable
+directly is not allowed).  From this point it is regarded as freezable
 and must call try_to_freeze() in a suitable place.
 
 IV. Why do we do that?
diff --git a/drivers/bluetooth/btmrvl_main.c b/drivers/bluetooth/btmrvl_main.c
index a88a78c86162..6c3defa50845 100644
--- a/drivers/bluetooth/btmrvl_main.c
+++ b/drivers/bluetooth/btmrvl_main.c
@@ -475,8 +475,6 @@ static int btmrvl_service_main_thread(void *data)
 
         init_waitqueue_entry(&wait, current);
 
-        current->flags |= PF_NOFREEZE;
-
         for (;;) {
                 add_wait_queue(&thread->wait_q, &wait);
 
diff --git a/drivers/mfd/twl6030-irq.c b/drivers/mfd/twl6030-irq.c
index 3eee45ffb096..c6b456ad7342 100644
--- a/drivers/mfd/twl6030-irq.c
+++ b/drivers/mfd/twl6030-irq.c
@@ -138,8 +138,6 @@ static int twl6030_irq_thread(void *data)
         static const unsigned max_i2c_errors = 100;
         int ret;
 
-        current->flags |= PF_NOFREEZE;
-
         while (!kthread_should_stop()) {
                 int i;
                 union {
diff --git a/drivers/staging/rts_pstor/rtsx.c b/drivers/staging/rts_pstor/rtsx.c
index 480b0ed2e4de..8a7803cf88d2 100644
--- a/drivers/staging/rts_pstor/rtsx.c
+++ b/drivers/staging/rts_pstor/rtsx.c
@@ -466,8 +466,6 @@ static int rtsx_control_thread(void *__dev)
         struct rtsx_chip *chip = dev->chip;
         struct Scsi_Host *host = rtsx_to_host(dev);
 
-        current->flags |= PF_NOFREEZE;
-
         for (;;) {
                 if (wait_for_completion_interruptible(&dev->cmnd_ready))
                         break;