drivers/tty/serial: deal with 8250_core.c uninitialized warning for good

Every couple of months, someone sends a patch to fix:

drivers/tty/serial/8250/8250_core.c: In function 'serial_unlink_irq_chain':
drivers/tty/serial/8250/8250_core.c:1712:2: warning: 'i' may be used uninitialized in this function [-Wuninitialized]

and they in turn get a NACK for their efforts, and are told that
their compiler is broken.  This has been going on since at least
the year 2008:  https://lkml.org/lkml/2008/11/24/433

Lets add a comment, so that subsequent patches don't get as far as
the maintainers or the mailing lists.

Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 69932b7556cf..747073b8c38a 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1694,6 +1694,10 @@ static int serial_link_irq_chain(struct uart_8250_port *up)
 
 static void serial_unlink_irq_chain(struct uart_8250_port *up)
 {
+        /*
+         * yes, some broken gcc emit "warning: 'i' may be used uninitialized"
+         * but no, we are not going to take a patch that assigns NULL below.
+         */
         struct irq_info *i;
         struct hlist_node *n;
         struct hlist_head *h;