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authorPeter Hurley <peter@hurleysoftware.com>2013-06-15 17:36:07 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-24 03:47:08 +0400
commit7391ee16950e772076d321792d9fbf030f921345 (patch)
treec0b17ff0622f801f05bb11228426bdc90e8ffdc2 /include/linux/tty.h
parent809850b7a5fcc0a96d023e1171a7944c60fd5a71 (diff)
downloadlinux-7391ee16950e772076d321792d9fbf030f921345.tar.xz
tty: Simplify flip buffer list with 0-sized sentinel
Use a 0-sized sentinel to avoid assigning the head ptr from the driver side thread. This also eliminates testing head/tail for NULL. When the sentinel is first 'consumed' by the buffer work (or by tty_buffer_flush()), it is detached from the list but not freed nor added to the free list. Both buffer work and tty_buffer_flush() continue to preserve at least 1 flip buffer to which head & tail is pointed. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/tty.h')
-rw-r--r--include/linux/tty.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5043b12f23ea..2e93eb831c61 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -67,6 +67,7 @@ static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
struct tty_bufhead {
struct work_struct work;
spinlock_t lock;
+ struct tty_buffer sentinel;
struct tty_buffer *head; /* Queue head */
struct tty_buffer *tail; /* Active buffer */
struct llist_head free; /* Free queue head */