TTY: simserial, remove support of shared interrupts
Jiri Slaby [Mon, 5 Mar 2012 13:52:17 +0000 (14:52 +0100)]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/ia64/hp/sim/simserial.c
include/linux/serialP.h

index d32b759..c35552d 100644 (file)
@@ -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;
index 6ce488c..b8543f9 100644 (file)
@@ -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 */