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dahdi: Channels can have their own file_operations structure.

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If we know that an open file is associated with a channel (pseudo or
real) we can just update the file->f_ops pointer so that we can short
circuit some of the checks in read/write/poll. Trades sizeof(file_operations)
bytes for less function call overhead in the "hot" path.

On a 2.4 GHz Xeon, saves around 150 ns on each read / write.

Review: https://reviewboard.asterisk.org/r/905/

Signed-off-by: Shaun Ruffell <sruffell@digium.com>

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9386 a0bf4364-ded3-4de4-8d8a-66a801d63aff
This commit is contained in:
Shaun Ruffell
2010-09-20 20:34:44 +00:00
parent 851203c182
commit 67fdba958c
1 changed files with 31 additions and 90 deletions
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121
drivers/dahdi/dahdi-base.c
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@@ -233,7 +233,6 @@ static sumtype *conf_sums;
static sumtype *conf_sums_prev;
static struct dahdi_span *master;
static struct file_operations dahdi_fops;
struct file_operations *dahdi_transcode_fops = NULL;
static struct {
@@ -2122,7 +2121,7 @@ static void dahdi_chan_unreg(struct dahdi_chan *chan)
}
static ssize_t dahdi_chan_read(struct file *file, char __user *usrbuf,
size_t count)
size_t count, loff_t *ppos)
{
struct dahdi_chan *chan = file->private_data;
int amnt;
@@ -2241,7 +2240,7 @@ static int num_filled_bufs(struct dahdi_chan *chan)
}
static ssize_t dahdi_chan_write(struct file *file, const char __user *usrbuf,
size_t count)
size_t count, loff_t *ppos)
{
unsigned long flags;
struct dahdi_chan *chan = file->private_data;
@@ -2805,6 +2804,8 @@ static int dahdi_timer_release(struct file *file)
return 0;
}
static const struct file_operations dahdi_chan_fops;
static int dahdi_specchan_open(struct file *file)
{
int res = 0;
@@ -2838,6 +2839,10 @@ static int dahdi_specchan_open(struct file *file)
if (!res) {
chan->file = file;
file->private_data = chan;
/* Since we know we're a channel now, we can
* update the f_op pointer and bypass a few of
* the checks on the minor number. */
file->f_op = &dahdi_chan_fops;
spin_unlock_irqrestore(&chan->lock, flags);
} else {
spin_unlock_irqrestore(&chan->lock, flags);
@@ -3003,69 +3008,6 @@ static int dahdi_open(struct file *file)
}
#endif
static ssize_t dahdi_read(struct file *file, char __user *usrbuf, size_t count, loff_t *ppos)
{
int unit = UNIT(file);
struct dahdi_chan *chan;
/* Can't read from control */
if (!unit) {
return -EINVAL;
}
if (unit == 253)
return -EINVAL;
if (unit == 254) {
chan = file->private_data;
if (!chan)
return -EINVAL;
return dahdi_chan_read(file, usrbuf, count);
}
if (unit == 255) {
chan = file->private_data;
if (!chan) {
module_printk(KERN_NOTICE, "No pseudo channel structure to read?\n");
return -EINVAL;
}
return dahdi_chan_read(file, usrbuf, count);
}
if (count < 0)
return -EINVAL;
return dahdi_chan_read(file, usrbuf, count);
}
static ssize_t dahdi_write(struct file *file, const char __user *usrbuf, size_t count, loff_t *ppos)
{
int unit = UNIT(file);
struct dahdi_chan *chan;
/* Can't read from control */
if (!unit)
return -EINVAL;
if (count < 0)
return -EINVAL;
if (unit == 253)
return -EINVAL;
if (unit == 254) {
chan = file->private_data;
if (!chan)
return -EINVAL;
return dahdi_chan_write(file, usrbuf, count);
}
if (unit == 255) {
chan = file->private_data;
if (!chan) {
module_printk(KERN_NOTICE, "No pseudo channel structure to read?\n");
return -EINVAL;
}
return dahdi_chan_write(file, usrbuf, count);
}
return dahdi_chan_write(file, usrbuf, count);
}
static int dahdi_set_default_zone(int defzone)
{
if ((defzone < 0) || (defzone >= DAHDI_TONE_ZONE_MAX))
@@ -8325,30 +8267,14 @@ dahdi_chan_poll(struct file *file, struct poll_table_struct *wait_table)
static unsigned int dahdi_poll(struct file *file, struct poll_table_struct *wait_table)
{
int unit = UNIT(file);
const int unit = UNIT(file);
if (!unit)
return -EINVAL;
if (unit == 250)
return dahdi_transcode_fops->poll(file, wait_table);
if (unit == 253)
if (likely(unit == 253))
return dahdi_timer_poll(file, wait_table);
if (unit == 254) {
if (!file->private_data)
return -EINVAL;
return dahdi_chan_poll(file, wait_table);
}
if (unit == 255) {
if (!file->private_data) {
module_printk(KERN_NOTICE, "No pseudo channel structure to read?\n");
return -EINVAL;
}
return dahdi_chan_poll(file, wait_table);
}
return dahdi_chan_poll(file, wait_table);
/* transcoders and channels should have updated their file_operations
* before poll is ever called. */
return -EINVAL;
}
static void __dahdi_transmit_chunk(struct dahdi_chan *chan, unsigned char *buf)
@@ -8868,7 +8794,7 @@ MODULE_VERSION(DAHDI_VERSION);
module_param(debug, int, 0644);
module_param(deftaps, int, 0644);
static struct file_operations dahdi_fops = {
static const struct file_operations dahdi_fops = {
.owner = THIS_MODULE,
.open = dahdi_open,
.release = dahdi_release,
@@ -8880,11 +8806,26 @@ static struct file_operations dahdi_fops = {
#else
.ioctl = dahdi_ioctl,
#endif
.read = dahdi_read,
.write = dahdi_write,
.poll = dahdi_poll,
};
static const struct file_operations dahdi_chan_fops = {
.owner = THIS_MODULE,
.open = dahdi_open,
.release = dahdi_release,
#ifdef HAVE_UNLOCKED_IOCTL
.unlocked_ioctl = dahdi_ioctl,
#ifdef HAVE_COMPAT_IOCTL
.compat_ioctl = dahdi_ioctl_compat,
#endif
#else
.ioctl = dahdi_ioctl,
#endif
.read = dahdi_chan_read,
.write = dahdi_chan_write,
.poll = dahdi_chan_poll,
};
#ifdef CONFIG_DAHDI_WATCHDOG
static struct timer_list watchdogtimer;