tty: introduce wait_event_interruptible_tty
Calling wait_event_interruptible implicitly
releases the BKL when it sleeps, but we need
to do this explcitly when we have converted
it to a mutex.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 6ead6b6..955d72e 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -607,5 +607,47 @@
}
#define tty_locked() (kernel_locked())
+/*
+ * wait_event_interruptible_tty -- wait for a condition with the tty lock held
+ *
+ * The condition we are waiting for might take a long time to
+ * become true, or might depend on another thread taking the
+ * BTM. In either case, we need to drop the BTM to guarantee
+ * forward progress. This is a leftover from the conversion
+ * from the BKL and should eventually get removed as the BTM
+ * falls out of use.
+ *
+ * Do not use in new code.
+ */
+#define wait_event_interruptible_tty(wq, condition) \
+({ \
+ int __ret = 0; \
+ if (!(condition)) { \
+ __wait_event_interruptible_tty(wq, condition, __ret); \
+ } \
+ __ret; \
+})
+
+#define __wait_event_interruptible_tty(wq, condition, ret) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ if (!signal_pending(current)) { \
+ tty_unlock(); \
+ schedule(); \
+ tty_lock(); \
+ continue; \
+ } \
+ ret = -ERESTARTSYS; \
+ break; \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+
#endif /* __KERNEL__ */
#endif