Statically allocate TX buffer

And also optimise struct elmcan{}'s size with pahole.

diff --git a/module/elmcan.c b/module/elmcan.c
index 94d031a70ef10ca564433eae3530c27b9eec3a97..85c656585f1551bea4328b16a8f1fcc7021dfe3e 100644 (file)
--- a/module/elmcan.c
+++ b/module/elmcan.c
@@ -58,7 +58,7 @@
 
 #define ELM327_NAPI_WEIGHT 4
 
-#define ELM327_SIZE_RXBUF 256
+#define ELM327_SIZE_RXBUF 224
 #define ELM327_SIZE_TXBUF 32
 
 #define ELM327_CAN_CONFIG_SEND_SFF           0x8000
@@ -89,6 +89,16 @@ struct elmcan {
 
        struct can_rx_offload offload;
 
+       /* TTY buffers */
+       u8 rxbuf[ELM327_SIZE_RXBUF];
+       u8 txbuf[ELM327_SIZE_TXBUF] ____cacheline_aligned;
+
+       /* TTY buffer accounting */
+       struct work_struct tx_work;     /* Flushes TTY TX buffer */
+       u8 *txhead;                     /* Next TX byte */
+       unsigned txleft;                /* Bytes left to TX */
+       int rxfill;                     /* Bytes already RX'd in buffer */
+
        /* TTY and netdev devices that we're bridging */
        struct tty_struct *tty;
        struct net_device *dev;
@@ -96,23 +106,6 @@ struct elmcan {
        /* Per-channel lock */
        spinlock_t lock;
 
-       /* Stop the channel on UART side hardware failure, e.g. stray
-        * characters or neverending lines. This may be caused by bad
-        * UART wiring, a bad ELM327, a bad UART bridge...
-        * Once this is true, nothing will be sent to the TTY.
-        */
-       bool uart_side_failure;
-
-       /* TTY TX helpers */
-       struct work_struct tx_work;     /* Flushes TTY TX buffer   */
-       u8 *txbuf;                      /* Pointer to our TX buffer */
-       u8 *txhead;                     /* Pointer to next TX byte */
-       unsigned txleft;                /* Bytes left to TX */
-
-       /* TTY RX helpers */
-       u8 rxbuf[ELM327_SIZE_RXBUF];
-       int rxfill;
-
        /* State machine */
        enum {
                ELM327_STATE_NOTINIT = 0,
@@ -121,7 +114,9 @@ struct elmcan {
                ELM327_STATE_RECEIVING,
        } state;
 
-       bool drop_next_line;
+       /* Things we have yet to send */
+       char **next_init_cmd;
+       unsigned long cmds_todo;
 
        /* The CAN frame and config the ELM327 is sending/using,
         * or will send/use after finishing all cmds_todo
@@ -130,9 +125,15 @@ struct elmcan {
        u16 can_config;
        u8 can_bitrate_divisor;
 
-       /* Things we have yet to send */
-       char **next_init_cmd;
-       unsigned long cmds_todo;
+       /* Parser state */
+       bool drop_next_line;
+
+       /* Stop the channel on UART side hardware failure, e.g. stray
+        * characters or neverending lines. This may be caused by bad
+        * UART wiring, a bad ELM327, a bad UART bridge...
+        * Once this is true, nothing will be sent to the TTY.
+        */
+       bool uart_side_failure;
 };
 
 static inline void elm327_uart_side_failure(struct elmcan *elm);
@@ -1055,12 +1056,6 @@ static int elmcan_ldisc_open(struct tty_struct *tty)
                return -ENFILE;
        elm = netdev_priv(dev);
 
-       elm->txbuf = kmalloc(ELM327_SIZE_TXBUF, GFP_KERNEL);
-       if (!elm->txbuf) {
-               err = -ENOMEM;
-               goto out_err;
-       }
-
        /* Configure TTY interface */
        tty->receive_room = 65536; /* We don't flow control */
        spin_lock_init(&elm->lock);
@@ -1092,7 +1087,6 @@ static int elmcan_ldisc_open(struct tty_struct *tty)
        return 0;
 
 out_err:
-       kfree(elm->txbuf);
        free_candev(elm->dev);
        return err;
 }
@@ -1122,7 +1116,6 @@ static void elmcan_ldisc_close(struct tty_struct *tty)
 
        netdev_info(elm->dev, "elmcan off %s.\n", tty->name);
 
-       kfree(elm->txbuf);
        free_candev(elm->dev);
 }