n_gsm: introduce enum gsm_mux_state

gsm_mux->state is clearly an enumeration. So introduce one and use it
-- compiler now checks if valid values are assigned to the field.

Note that a compiler warns about unhandled cases in switch. Add default
cases with a pr_debug (which is not printed by default).

The values of the states are preserved thanks to the nature of enum.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200219084949.28074-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 7fee5a5..82e3d88 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -173,6 +173,20 @@ struct gsm_control {
        int error;      /* Error if any */
 };
 
+enum gsm_mux_state {
+       GSM_SEARCH,
+       GSM_START,
+       GSM_ADDRESS,
+       GSM_CONTROL,
+       GSM_LEN,
+       GSM_DATA,
+       GSM_FCS,
+       GSM_OVERRUN,
+       GSM_LEN0,
+       GSM_LEN1,
+       GSM_SSOF,
+};
+
 /*
  *     Each GSM mux we have is represented by this structure. If we are
  *     operating as an ldisc then we use this structure as our ldisc
@@ -197,18 +211,7 @@ struct gsm_mux {
 
        /* Framing Layer */
        unsigned char *buf;
-       int state;
-#define GSM_SEARCH             0
-#define GSM_START              1
-#define GSM_ADDRESS            2
-#define GSM_CONTROL            3
-#define GSM_LEN                        4
-#define GSM_DATA               5
-#define GSM_FCS                        6
-#define GSM_OVERRUN            7
-#define GSM_LEN0               8
-#define GSM_LEN1               9
-#define GSM_SSOF               10
+       enum gsm_mux_state state;
        unsigned int len;
        unsigned int address;
        unsigned int count;
@@ -1934,6 +1937,9 @@ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
                        break;
                }
                break;
+       default:
+               pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
+               break;
        }
 }
 
@@ -2008,6 +2014,9 @@ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
                break;
        case GSM_OVERRUN:       /* Over-long - eg a dropped SOF */
                break;
+       default:
+               pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
+               break;
        }
 }