Staging: comedi: serial2002: Reduce stack usage on 'open'

Reduce stack usage in serial_2002_open() by allocating dig_in_config,
dig_out_config, chan_in_config, and chan_out_config temporary arrays
using kcalloc() and freeing them when done with.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/comedi/drivers/serial2002.c b/drivers/staging/comedi/drivers/serial2002.c
index 6813e34..c929f98 100644 (file)
--- a/drivers/staging/comedi/drivers/serial2002.c
+++ b/drivers/staging/comedi/drivers/serial2002.c
@@ -412,30 +412,25 @@ static int serial_2002_open(struct comedi_device *dev)
                        int max;
                };
 
-               struct config_t dig_in_config[32];
-               struct config_t dig_out_config[32];
-               struct config_t chan_in_config[32];
-               struct config_t chan_out_config[32];
+               struct config_t *dig_in_config;
+               struct config_t *dig_out_config;
+               struct config_t *chan_in_config;
+               struct config_t *chan_out_config;
                int i;
 
                result = 0;
-               for (i = 0; i < 32; i++) {
-                       dig_in_config[i].kind = 0;
-                       dig_in_config[i].bits = 0;
-                       dig_in_config[i].min = 0;
-                       dig_in_config[i].max = 0;
-                       dig_out_config[i].kind = 0;
-                       dig_out_config[i].bits = 0;
-                       dig_out_config[i].min = 0;
-                       dig_out_config[i].max = 0;
-                       chan_in_config[i].kind = 0;
-                       chan_in_config[i].bits = 0;
-                       chan_in_config[i].min = 0;
-                       chan_in_config[i].max = 0;
-                       chan_out_config[i].kind = 0;
-                       chan_out_config[i].bits = 0;
-                       chan_out_config[i].min = 0;
-                       chan_out_config[i].max = 0;
+               dig_in_config = kcalloc(32, sizeof(struct config_t),
+                               GFP_KERNEL);
+               dig_out_config = kcalloc(32, sizeof(struct config_t),
+                               GFP_KERNEL);
+               chan_in_config = kcalloc(32, sizeof(struct config_t),
+                               GFP_KERNEL);
+               chan_out_config = kcalloc(32, sizeof(struct config_t),
+                               GFP_KERNEL);
+               if (!dig_in_config || !dig_out_config
+                   || !chan_in_config || !chan_out_config) {
+                       result = -ENOMEM;
+                       goto err_alloc_configs;
                }
 
                tty_setspeed(devpriv->tty, devpriv->speed);
@@ -690,6 +685,13 @@ static int serial_2002_open(struct comedi_device *dev)
                                s->range_table_list = NULL;
                        }
                }
+
+err_alloc_configs:
+               kfree(dig_in_config);
+               kfree(dig_out_config);
+               kfree(chan_in_config);
+               kfree(chan_out_config);
+
                if (result) {
                        if (devpriv->tty) {
                                filp_close(devpriv->tty, 0);