Hi Marcin,
On Mon, 25 Feb 2008 21:51:00 +0100, Marcin Slusarz wrote:
> ir_probe allocated struct i2c_client on stack;
> it's pretty big structure, so allocate it with kzalloc
>
> make checkstack output without this patch:
> x059d ir_probe [ir-kbd-i2c]: 1000
>
> compile tested only
>
> Signed-off-by: Marcin Slusarz <[EMAIL PROTECTED]>
> Cc: Mauro Carvalho Chehab <[EMAIL PROTECTED]>
> Cc: Jean Delvare <[EMAIL PROTECTED]>
> ---
> drivers/media/video/ir-kbd-i2c.c | 18 +++++++++++-------
> 1 files changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/media/video/ir-kbd-i2c.c
> b/drivers/media/video/ir-kbd-i2c.c
> index 9851987..aec122f 100644
> --- a/drivers/media/video/ir-kbd-i2c.c
> +++ b/drivers/media/video/ir-kbd-i2c.c
> @@ -510,9 +510,9 @@ static int ir_probe(struct i2c_adapter *adap)
> static const int probe_cx88[] = { 0x18, 0x6b, 0x71, -1 };
> static const int probe_cx23885[] = { 0x6b, -1 };
> const int *probe = NULL;
> - struct i2c_client c;
> + struct i2c_client *c;
> unsigned char buf;
> - int i,rc;
> + int i, rc;
>
> switch (adap->id) {
> case I2C_HW_B_BT848:
> @@ -537,19 +537,23 @@ static int ir_probe(struct i2c_adapter *adap)
> if (NULL == probe)
> return 0;
>
> - memset(&c,0,sizeof(c));
> - c.adapter = adap;
> + c = kzalloc(sizeof(*c), GFP_KERNEL);
> + if (!c)
> + return -ENOMEM;
> +
> + c->adapter = adap;
> for (i = 0; -1 != probe[i]; i++) {
> - c.addr = probe[i];
> - rc = i2c_master_recv(&c,&buf,0);
> + c->addr = probe[i];
> + rc = i2c_master_recv(c, &buf, 0);
> dprintk(1,"probe 0x%02x @ %s: %s\n",
> probe[i], adap->name,
> (0 == rc) ? "yes" : "no");
> if (0 == rc) {
> - ir_attach(adap,probe[i],0,0);
> + ir_attach(adap, probe[i], 0, 0);
> break;
> }
> }
> + kfree(c);
> return 0;
> }
>
While this works, I'd rather change the code to call i2c_transfer()
instead of i2c_master_recv(). i2c_transfer() is meant exactly for this
case (no i2c_client at hand.) This solves the stack usage problem
without requiring a temporary memory allocation:
* * * * *
Limit stack usage in ir_probe by calling i2c_transfer, which doesn't
require a struct i2c_client, instead of i2c_master_recv which does.
Signed-off-by: Jean Delvare <[EMAIL PROTECTED]>
---
drivers/media/video/ir-kbd-i2c.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
--- linux-2.6.25-rc3.orig/drivers/media/video/ir-kbd-i2c.c 2008-02-26
11:35:51.000000000 +0100
+++ linux-2.6.25-rc3/drivers/media/video/ir-kbd-i2c.c 2008-02-26
11:44:54.000000000 +0100
@@ -510,8 +510,11 @@ static int ir_probe(struct i2c_adapter *
static const int probe_cx88[] = { 0x18, 0x6b, 0x71, -1 };
static const int probe_cx23885[] = { 0x6b, -1 };
const int *probe = NULL;
- struct i2c_client c;
- unsigned char buf;
+ struct i2c_msg msg = {
+ .flags = I2C_M_RD,
+ .len = 0,
+ .buf = NULL,
+ };
int i,rc;
switch (adap->id) {
@@ -537,15 +540,13 @@ static int ir_probe(struct i2c_adapter *
if (NULL == probe)
return 0;
- memset(&c,0,sizeof(c));
- c.adapter = adap;
for (i = 0; -1 != probe[i]; i++) {
- c.addr = probe[i];
- rc = i2c_master_recv(&c,&buf,0);
+ msg.addr = probe[i];
+ rc = i2c_transfer(adap, &msg, 1);
dprintk(1,"probe 0x%02x @ %s: %s\n",
probe[i], adap->name,
- (0 == rc) ? "yes" : "no");
- if (0 == rc) {
+ (1 == rc) ? "yes" : "no");
+ if (1 == rc) {
ir_attach(adap,probe[i],0,0);
break;
}
Built-tested, I've also tested loading the ir-kbd-i2c driver on an
unsupported cx88 adapter. Review and more testing welcome.
--
Jean Delvare
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