V4L/DVB: dib7000p: reduce large stack usage

This patch reduces static stack usage of one of the 2 top offenders
as listed by 'make checkstack':

Building with CONFIG_FRAME_WARN=2048 produces:

drivers/media/dvb/frontends/dib7000p.c:1367: warning: the frame size of 2320 bytes is larger than 2048 bytes

and in 'make checkstack', the stack usage goes from:
0x00002409 dib7000p_i2c_enumeration [dib7000p]:		2328
to unlisted with this patch.

Also change one caller of dib7000p_i2c_enumeration() to check its
return value.

I don't have the hardware that is needed to test this patch.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/dvb/dvb-usb/cxusb.c b/drivers/media/dvb/dvb-usb/cxusb.c
index 33a83f9..0eb4908 100644 (file)
--- a/drivers/media/dvb/dvb-usb/cxusb.c
+++ b/drivers/media/dvb/dvb-usb/cxusb.c
@@ -1025,8 +1025,9 @@ static int cxusb_dualdig4_rev2_frontend_attach(struct dvb_usb_adapter *adap)
 
        cxusb_bluebird_gpio_pulse(adap->dev, 0x02, 1);
 
-       dib7000p_i2c_enumeration(&adap->dev->i2c_adap, 1, 18,
-                                &cxusb_dualdig4_rev2_config);
+       if (dib7000p_i2c_enumeration(&adap->dev->i2c_adap, 1, 18,
+                                &cxusb_dualdig4_rev2_config) < 0)
+               return -ENODEV;
 
        adap->fe = dvb_attach(dib7000p_attach, &adap->dev->i2c_adap, 0x80,
                              &cxusb_dualdig4_rev2_config);

diff --git a/drivers/media/dvb/frontends/dib7000p.c b/drivers/media/dvb/frontends/dib7000p.c
index 85468a4..113fc13 100644 (file)
--- a/drivers/media/dvb/frontends/dib7000p.c
+++ b/drivers/media/dvb/frontends/dib7000p.c
@@ -1324,46 +1324,54 @@ EXPORT_SYMBOL(dib7000p_pid_filter);
 
 int dib7000p_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 default_addr, struct dib7000p_config cfg[])
 {
-       struct dib7000p_state st = { .i2c_adap = i2c };
+       struct dib7000p_state *dpst;
        int k = 0;
        u8 new_addr = 0;
 
+       dpst = kzalloc(sizeof(struct dib7000p_state), GFP_KERNEL);
+       if (!dpst)
+               return -ENODEV;
+
+       dpst->i2c_adap = i2c;
+
        for (k = no_of_demods-1; k >= 0; k--) {
-               st.cfg = cfg[k];
+               dpst->cfg = cfg[k];
 
                /* designated i2c address */
                new_addr          = (0x40 + k) << 1;
-               st.i2c_addr = new_addr;
-               dib7000p_write_word(&st, 1287, 0x0003); /* sram lead in, rdy */
-               if (dib7000p_identify(&st) != 0) {
-                       st.i2c_addr = default_addr;
-                       dib7000p_write_word(&st, 1287, 0x0003); /* sram lead in, rdy */
-                       if (dib7000p_identify(&st) != 0) {
+               dpst->i2c_addr = new_addr;
+               dib7000p_write_word(dpst, 1287, 0x0003); /* sram lead in, rdy */
+               if (dib7000p_identify(dpst) != 0) {
+                       dpst->i2c_addr = default_addr;
+                       dib7000p_write_word(dpst, 1287, 0x0003); /* sram lead in, rdy */
+                       if (dib7000p_identify(dpst) != 0) {
                                dprintk("DiB7000P #%d: not identified\n", k);
+                               kfree(dpst);
                                return -EIO;
                        }
                }
 
                /* start diversity to pull_down div_str - just for i2c-enumeration */
-               dib7000p_set_output_mode(&st, OUTMODE_DIVERSITY);
+               dib7000p_set_output_mode(dpst, OUTMODE_DIVERSITY);
 
                /* set new i2c address and force divstart */
-               dib7000p_write_word(&st, 1285, (new_addr << 2) | 0x2);
+               dib7000p_write_word(dpst, 1285, (new_addr << 2) | 0x2);
 
                dprintk("IC %d initialized (to i2c_address 0x%x)", k, new_addr);
        }
 
        for (k = 0; k < no_of_demods; k++) {
-               st.cfg = cfg[k];
-               st.i2c_addr = (0x40 + k) << 1;
+               dpst->cfg = cfg[k];
+               dpst->i2c_addr = (0x40 + k) << 1;
 
                // unforce divstr
-               dib7000p_write_word(&st, 1285, st.i2c_addr << 2);
+               dib7000p_write_word(dpst, 1285, dpst->i2c_addr << 2);
 
                /* deactivate div - it was just for i2c-enumeration */
-               dib7000p_set_output_mode(&st, OUTMODE_HIGH_Z);
+               dib7000p_set_output_mode(dpst, OUTMODE_HIGH_Z);
        }
 
+       kfree(dpst);
        return 0;
 }
 EXPORT_SYMBOL(dib7000p_i2c_enumeration);