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Subject[PATCH 30/68] TTY: simserial, remove support of shared interrupts
Date
It never worked there. The ISR was never written for that kind of
stuff. So remove all that crap with a hash of linked lists and pass
the pointer directly to the ISR.

BTW this answers the question there:
* I don't know exactly why they don't use the dev_id opaque data
* pointer instead of this extra lookup table

-> Because they thought they will support more devices bound to a
single interrupt w/o IRQF_SHARED. They would need exactly the hash
there.

What I don't understand is rebinding of the interrupt in the shutdown
path. They perhaps meant to do just synchronize_irq? In any case, this
is all gone and free_irq there properly.

By removing the hash we save some bits (exactly NR_IRQS * 8 bytes of
.bss and over a kilo of .text):
before:
text data bss dec hex filename
19600 320 8227 28147 6df3 ../a/ia64/arch/ia64/hp/sim/simserial.o
after:
text data bss dec hex filename
18568 320 28 18916 49e4 ../a/ia64/arch/ia64/hp/sim/simserial.o

Note that a shared interrupt could not work too. request_irq requires
data parameter to be non-NULL. So the whole IRQ_T exercise was
pointless.

Finally, this helps us remove another two members of async_struct :).

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
---
arch/ia64/hp/sim/simserial.c | 64 +++++-------------------------------------
include/linux/serialP.h | 2 --
2 files changed, 7 insertions(+), 59 deletions(-)

diff --git a/arch/ia64/hp/sim/simserial.c b/arch/ia64/hp/sim/simserial.c
index d32b759..c35552d 100644
--- a/arch/ia64/hp/sim/simserial.c
+++ b/arch/ia64/hp/sim/simserial.c
@@ -92,8 +92,6 @@ static struct serial_uart_config uart_config[] = {

struct tty_driver *hp_simserial_driver;

-static struct async_struct *IRQ_ports[NR_IRQS];
-
static struct console *console;

static unsigned char *tmp_buf;
@@ -167,14 +165,9 @@ static void receive_chars(struct tty_struct *tty)
*/
static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
{
- struct async_struct * info;
+ struct async_struct *info = dev_id;

- /*
- * I don't know exactly why they don't use the dev_id opaque data
- * pointer instead of this extra lookup table
- */
- info = IRQ_ports[irq];
- if (!info || !info->tty) {
+ if (!info->tty) {
printk(KERN_INFO "simrs_interrupt_single: info|tty=0 info=%p problem\n", info);
return IRQ_NONE;
}
@@ -456,7 +449,6 @@ static void shutdown(struct async_struct * info)
{
unsigned long flags;
struct serial_state *state = info->state;
- int retval;

if (!(state->flags & ASYNC_INITIALIZED))
return;
@@ -468,33 +460,8 @@ static void shutdown(struct async_struct * info)

local_irq_save(flags);
{
- /*
- * First unlink the serial port from the IRQ chain...
- */
- if (info->next_port)
- info->next_port->prev_port = info->prev_port;
- if (info->prev_port)
- info->prev_port->next_port = info->next_port;
- else
- IRQ_ports[state->irq] = info->next_port;
-
- /*
- * Free the IRQ, if necessary
- */
- if (state->irq && (!IRQ_ports[state->irq] ||
- !IRQ_ports[state->irq]->next_port)) {
- if (IRQ_ports[state->irq]) {
- free_irq(state->irq, NULL);
- retval = request_irq(state->irq, rs_interrupt_single,
- IRQ_T(state), "serial",
- NULL);
-
- if (retval)
- printk(KERN_ERR "serial shutdown: request_irq: error %d"
- " Couldn't reacquire IRQ.\n", retval);
- } else
- free_irq(state->irq, NULL);
- }
+ if (state->irq)
+ free_irq(state->irq, info);

if (info->xmit.buf) {
free_page((unsigned long) info->xmit.buf);
@@ -645,7 +612,6 @@ startup(struct async_struct *info)
{
unsigned long flags;
int retval=0;
- irq_handler_t handler;
struct serial_state *state= info->state;
unsigned long page;

@@ -677,29 +643,13 @@ startup(struct async_struct *info)
/*
* Allocate the IRQ if necessary
*/
- if (state->irq && (!IRQ_ports[state->irq] ||
- !IRQ_ports[state->irq]->next_port)) {
- if (IRQ_ports[state->irq]) {
- retval = -EBUSY;
- goto errout;
- } else
- handler = rs_interrupt_single;
-
- retval = request_irq(state->irq, handler, IRQ_T(state),
- "simserial", NULL);
+ if (state->irq) {
+ retval = request_irq(state->irq, rs_interrupt_single,
+ IRQ_T(state), "simserial", info);
if (retval)
goto errout;
}

- /*
- * Insert serial port into IRQ chain.
- */
- info->prev_port = NULL;
- info->next_port = IRQ_ports[state->irq];
- if (info->next_port)
- info->next_port->prev_port = info;
- IRQ_ports[state->irq] = info;
-
if (info->tty) clear_bit(TTY_IO_ERROR, &info->tty->flags);

info->xmit.head = info->xmit.tail = 0;
diff --git a/include/linux/serialP.h b/include/linux/serialP.h
index 6ce488c..b8543f9 100644
--- a/include/linux/serialP.h
+++ b/include/linux/serialP.h
@@ -56,8 +56,6 @@ struct async_struct {
wait_queue_head_t open_wait;
wait_queue_head_t close_wait;
wait_queue_head_t delta_msr_wait;
- struct async_struct *next_port; /* For the linked list */
- struct async_struct *prev_port;
};

#endif /* _LINUX_SERIAL_H */
--
1.7.9.2



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