aboutsummaryrefslogtreecommitdiff
path: root/drivers/platform/x86/thinkpad_acpi.c
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2011-11-21 12:32:23 -0800
committerTejun Heo <tj@kernel.org>2011-11-21 12:32:23 -0800
commit8a32c441c1609f80e55df75422324a1151208f40 (patch)
tree73884b06cc2db3ea155af9a88815bb5105a4473e /drivers/platform/x86/thinkpad_acpi.c
parenta0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6 (diff)
downloadlinux-linaro-stable-8a32c441c1609f80e55df75422324a1151208f40.tar.gz
freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent deadlock between the freezer and kthread_stop(); unfortunately, this is inherently racy - nothing prevents freezing from happening between thaw_process() and kthread_stop(). This patch implements kthread_freezable_should_stop() which enters refrigerator if necessary but is guaranteed to return if kthread_stop() is invoked. Both thaw_process() users are converted to use the new function. Note that this deadlock condition exists for many of freezable kthreads. They need to be converted to use the new should_stop or freezable workqueue. Tested with synthetic test case. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br> Cc: Jens Axboe <axboe@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'drivers/platform/x86/thinkpad_acpi.c')
-rw-r--r--drivers/platform/x86/thinkpad_acpi.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 7b828680b21d..4b11fc91fa7d 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -2456,8 +2456,9 @@ static int hotkey_kthread(void *data)
u32 poll_mask, event_mask;
unsigned int si, so;
unsigned long t;
- unsigned int change_detector, must_reset;
+ unsigned int change_detector;
unsigned int poll_freq;
+ bool was_frozen;
mutex_lock(&hotkey_thread_mutex);
@@ -2488,14 +2489,14 @@ static int hotkey_kthread(void *data)
t = 100; /* should never happen... */
}
t = msleep_interruptible(t);
- if (unlikely(kthread_should_stop()))
+ if (unlikely(kthread_freezable_should_stop(&was_frozen)))
break;
- must_reset = try_to_freeze();
- if (t > 0 && !must_reset)
+
+ if (t > 0 && !was_frozen)
continue;
mutex_lock(&hotkey_thread_data_mutex);
- if (must_reset || hotkey_config_change != change_detector) {
+ if (was_frozen || hotkey_config_change != change_detector) {
/* forget old state on thaw or config change */
si = so;
t = 0;
@@ -2528,10 +2529,6 @@ exit:
static void hotkey_poll_stop_sync(void)
{
if (tpacpi_hotkey_task) {
- if (frozen(tpacpi_hotkey_task) ||
- freezing(tpacpi_hotkey_task))
- thaw_process(tpacpi_hotkey_task);
-
kthread_stop(tpacpi_hotkey_task);
tpacpi_hotkey_task = NULL;
mutex_lock(&hotkey_thread_mutex);