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authorPeter Zijlstra <peterz@infradead.org>2014-09-24 10:18:55 +0200
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:56:52 +0100
commit8eb23b9f35aae413140d3fda766a98092c21e9b0 (patch)
tree657a91ed72882475ada772da052a8a332d70a2dc /include/linux/sched.h
parent26cabd31259ba43f68026ce3f62b78094124333f (diff)
downloadop-kernel-dev-8eb23b9f35aae413140d3fda766a98092c21e9b0.zip
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sched: Debug nested sleeps
Validate we call might_sleep() with TASK_RUNNING, which catches places where we nest blocking primitives, eg. mutex usage in a wait loop. Since all blocking is arranged through task_struct::state, nesting this will cause the inner primitive to set TASK_RUNNING and the outer will thus not block. Another observed problem is calling a blocking function from schedule()->sched_submit_work()->blk_schedule_flush_plug() which will then destroy the task state for the actual __schedule() call that comes after it. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: oleg@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140924082242.591637616@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/sched.h')
-rw-r--r--include/linux/sched.h46
1 files changed, 44 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 320a977..4648e07 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -243,6 +243,43 @@ extern char ___assert_task_state[1 - 2*!!(
((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
(task->flags & PF_FROZEN) == 0)
+#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
+
+#define __set_task_state(tsk, state_value) \
+ do { \
+ (tsk)->task_state_change = _THIS_IP_; \
+ (tsk)->state = (state_value); \
+ } while (0)
+#define set_task_state(tsk, state_value) \
+ do { \
+ (tsk)->task_state_change = _THIS_IP_; \
+ set_mb((tsk)->state, (state_value)); \
+ } while (0)
+
+/*
+ * set_current_state() includes a barrier so that the write of current->state
+ * is correctly serialised wrt the caller's subsequent test of whether to
+ * actually sleep:
+ *
+ * set_current_state(TASK_UNINTERRUPTIBLE);
+ * if (do_i_need_to_sleep())
+ * schedule();
+ *
+ * If the caller does not need such serialisation then use __set_current_state()
+ */
+#define __set_current_state(state_value) \
+ do { \
+ current->task_state_change = _THIS_IP_; \
+ current->state = (state_value); \
+ } while (0)
+#define set_current_state(state_value) \
+ do { \
+ current->task_state_change = _THIS_IP_; \
+ set_mb(current->state, (state_value)); \
+ } while (0)
+
+#else
+
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
#define set_task_state(tsk, state_value) \
@@ -259,11 +296,13 @@ extern char ___assert_task_state[1 - 2*!!(
*
* If the caller does not need such serialisation then use __set_current_state()
*/
-#define __set_current_state(state_value) \
+#define __set_current_state(state_value) \
do { current->state = (state_value); } while (0)
-#define set_current_state(state_value) \
+#define set_current_state(state_value) \
set_mb(current->state, (state_value))
+#endif
+
/* Task command name length */
#define TASK_COMM_LEN 16
@@ -1661,6 +1700,9 @@ struct task_struct {
unsigned int sequential_io;
unsigned int sequential_io_avg;
#endif
+#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
+ unsigned long task_state_change;
+#endif
};
/* Future-safe accessor for struct task_struct's cpus_allowed. */
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