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firewire: cdev: reduce stack usage by ioctl_dispatch

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Replace a hardcoded buffer size by a sizeof union {}.  This shrinks the
stack-allocated ioctl argument buffer from 256 to 40 bytes.  (This is
not much, but subsequent stack usage particularly by the queue_iso ioctl
handler adds up.)

The new form is also easier to keep up to date than a hardcoded size if
more ioctls are added.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2009-10-15 21:16:53 +02:00
parent 19593ffdb6
commit b2c0a2ac3e
1 changed files with 17 additions and 1 deletions
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18
drivers/firewire/core-cdev.c
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@ -1299,7 +1299,23 @@ static int (* const ioctl_handlers[])(struct client *client, void *buffer) = {
static int dispatch_ioctl(struct client *client,
unsigned int cmd, void __user *arg)
{
char buffer[256];
char buffer[sizeof(union {
struct fw_cdev_get_info _00;
struct fw_cdev_send_request _01;
struct fw_cdev_allocate _02;
struct fw_cdev_deallocate _03;
struct fw_cdev_send_response _04;
struct fw_cdev_initiate_bus_reset _05;
struct fw_cdev_add_descriptor _06;
struct fw_cdev_remove_descriptor _07;
struct fw_cdev_create_iso_context _08;
struct fw_cdev_queue_iso _09;
struct fw_cdev_start_iso _0a;
struct fw_cdev_stop_iso _0b;
struct fw_cdev_get_cycle_timer _0c;
struct fw_cdev_allocate_iso_resource _0d;
struct fw_cdev_send_stream_packet _13;
})];
int ret;
if (_IOC_TYPE(cmd) != '#' ||