This is needed by bluetooth.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
backport/backport-include/linux/wait.h | 9 ++++
backport/compat/Makefile | 1 +
backport/compat/backport-3.19.c | 79 ++++++++++++++++++++++++++++++++++
3 files changed, 89 insertions(+)
create mode 100644 backport/compat/backport-3.19.c
diff --git a/backport/backport-include/linux/wait.h b/backport/backport-include/linux/wait.h
index dfb111d..4057ff1 100644
--- a/backport/backport-include/linux/wait.h
+++ b/backport/backport-include/linux/wait.h
@@ -23,4 +23,13 @@ backport_wait_on_bit_io(void *word, int bit, unsigned mode)
#endif
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,19,0)
+#define WQ_FLAG_WOKEN 0x02
+
+#define wait_woken LINUX_BACKPORT(wait_woken)
+long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
+#define wait_woken LINUX_BACKPORT(wait_woken)
+int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
+#endif
+
#endif /* __BACKPORT_LINUX_WAIT_H */
diff --git a/backport/compat/Makefile b/backport/compat/Makefile
index f14b516..3d905ed 100644
--- a/backport/compat/Makefile
+++ b/backport/compat/Makefile
@@ -24,6 +24,7 @@ compat-$(CPTCFG_KERNEL_3_14) += backport-3.14.o
compat-$(CPTCFG_KERNEL_3_15) += backport-3.15.o
compat-$(CPTCFG_KERNEL_3_17) += backport-3.17.o
compat-$(CPTCFG_KERNEL_3_18) += backport-3.18.o
+compat-$(CPTCFG_KERNEL_3_19) += backport-3.19.o
compat-$(CPTCFG_BPAUTO_BUILD_CRYPTO_CCM) += crypto-ccm.o
compat-$(CPTCFG_BPAUTO_BUILD_DMA_SHARED_HELPERS) += dma-shared-helpers.o
diff --git a/backport/compat/backport-3.19.c b/backport/compat/backport-3.19.c
new file mode 100644
index 0000000..18cba4d
--- /dev/null
+++ b/backport/compat/backport-3.19.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2014 Hauke Mehrtens <hauke@xxxxxxxxxx>
+ *
+ * Backport functionality introduced in Linux 3.18.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+#include <linux/export.h>
+
+
+static inline bool is_kthread_should_stop(void)
+{
+ return (current->flags & PF_KTHREAD) && kthread_should_stop();
+}
+
+/*
+ * DEFINE_WAIT_FUNC(wait, woken_wake_func);
+ *
+ * add_wait_queue(&wq, &wait);
+ * for (;;) {
+ * if (condition)
+ * break;
+ *
+ * p->state = mode; condition = true;
+ * smp_mb(); // A smp_wmb(); // C
+ * if (!wait->flags & WQ_FLAG_WOKEN) wait->flags |= WQ_FLAG_WOKEN;
+ * schedule() try_to_wake_up();
+ * p->state = TASK_RUNNING; ~~~~~~~~~~~~~~~~~~
+ * wait->flags &= ~WQ_FLAG_WOKEN; condition = true;
+ * smp_mb() // B smp_wmb(); // C
+ * wait->flags |= WQ_FLAG_WOKEN;
+ * }
+ * remove_wait_queue(&wq, &wait);
+ *
+ */
+long wait_woken(wait_queue_t *wait, unsigned mode, long timeout)
+{
+ set_current_state(mode); /* A */
+ /*
+ * The above implies an smp_mb(), which matches with the smp_wmb() from
+ * woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must
+ * also observe all state before the wakeup.
+ */
+ if (!(wait->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
+ timeout = schedule_timeout(timeout);
+ __set_current_state(TASK_RUNNING);
+
+ /*
+ * The below implies an smp_mb(), it too pairs with the smp_wmb() from
+ * woken_wake_function() such that we must either observe the wait
+ * condition being true _OR_ WQ_FLAG_WOKEN such that we will not miss
+ * an event.
+ */
+ set_mb(wait->flags, wait->flags & ~WQ_FLAG_WOKEN); /* B */
+
+ return timeout;
+}
+EXPORT_SYMBOL(wait_woken);
+
+int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+ /*
+ * Although this function is called under waitqueue lock, LOCK
+ * doesn't imply write barrier and the users expects write
+ * barrier semantics on wakeup functions. The following
+ * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
+ * and is paired with set_mb() in wait_woken().
+ */
+ smp_wmb(); /* C */
+ wait->flags |= WQ_FLAG_WOKEN;
+
+ return default_wake_function(wait, mode, sync, key);
+}
+EXPORT_SYMBOL(woken_wake_function);
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe backports" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
