linux/arch/um/kernel/irq_user.c

/*
 * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/poll.h>
#include <sys/types.h>
#include <sys/time.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "process.h"
#include "sigio.h"
#include "irq_user.h"
#include "os.h"
#include "misc_constants.h"

struct irq_fd *active_fds = NULL;
static struct irq_fd **last_irq_ptr = &active_fds;

extern void free_irqs(void);

void sigio_handler(int sig, union uml_pt_regs *regs)
{
	struct irq_fd *irq_fd;
	int n;

	if(smp_sigio_handler()) return;
	while(1){
		n = os_waiting_for_events(active_fds);
		if (n <= 0) {
			if(n == -EINTR) continue;
			else break;
 		}

		for(irq_fd = active_fds; irq_fd != NULL; irq_fd = irq_fd->next){
			if(irq_fd->current_events != 0){
				irq_fd->current_events = 0;
				do_IRQ(irq_fd->irq, regs);
			}
		}
	}

	free_irqs();
}

static void maybe_sigio_broken(int fd, int type)
{
	if(os_isatty(fd)){
		if((type == IRQ_WRITE) && !pty_output_sigio){
			write_sigio_workaround();
			add_sigio_fd(fd, 0);
		}
		else if((type == IRQ_READ) && !pty_close_sigio){
			write_sigio_workaround();
			add_sigio_fd(fd, 1);			
		}
	}
}


int activate_fd(int irq, int fd, int type, void *dev_id)
{
	struct pollfd *tmp_pfd;
	struct irq_fd *new_fd, *irq_fd;
	unsigned long flags;
	int pid, events, err, n;

	pid = os_getpid();
	err = os_set_fd_async(fd, pid);
	if(err < 0)
		goto out;

	new_fd = um_kmalloc(sizeof(*new_fd));
	err = -ENOMEM;
	if(new_fd == NULL)
		goto out;

	if(type == IRQ_READ) events = UM_POLLIN | UM_POLLPRI;
	else events = UM_POLLOUT;
	*new_fd = ((struct irq_fd) { .next  		= NULL,
				     .id 		= dev_id,
				     .fd 		= fd,
				     .type 		= type,
				     .irq 		= irq,
				     .pid  		= pid,
				     .events 		= events,
				     .current_events 	= 0 } );

	/* Critical section - locked by a spinlock because this stuff can
	 * be changed from interrupt handlers.  The stuff above is done
	 * outside the lock because it allocates memory.
	 */

	/* Actually, it only looks like it can be called from interrupt
	 * context.  The culprit is reactivate_fd, which calls
	 * maybe_sigio_broken, which calls write_sigio_workaround,
	 * which calls activate_fd.  However, write_sigio_workaround should
	 * only be called once, at boot time.  That would make it clear that
	 * this is called only from process context, and can be locked with
	 * a semaphore.
	 */
	flags = irq_lock();
	for(irq_fd = active_fds; irq_fd != NULL; irq_fd = irq_fd->next){
		if((irq_fd->fd == fd) && (irq_fd->type == type)){
			printk("Registering fd %d twice\n", fd);
			printk("Irqs : %d, %d\n", irq_fd->irq, irq);
			printk("Ids : 0x%x, 0x%x\n", irq_fd->id, dev_id);
			goto out_unlock;
		}
	}

	/*-------------*/
	if(type == IRQ_WRITE)
		fd = -1;

	tmp_pfd = NULL;
	n = 0;

	while(1){
		n = os_create_pollfd(fd, events, tmp_pfd, n);
		if (n == 0)
			break;

		/* n > 0
		 * It means we couldn't put new pollfd to current pollfds
		 * and tmp_fds is NULL or too small for new pollfds array.
		 * Needed size is equal to n as minimum.
		 *
		 * Here we have to drop the lock in order to call
		 * kmalloc, which might sleep.
		 * If something else came in and changed the pollfds array
		 * so we will not be able to put new pollfd struct to pollfds
		 * then we free the buffer tmp_fds and try again.
		 */
		irq_unlock(flags);
		if (tmp_pfd != NULL) {
			kfree(tmp_pfd);
			tmp_pfd = NULL;
		}

		tmp_pfd = um_kmalloc(n);
		if (tmp_pfd == NULL)
			goto out_kfree;

		flags = irq_lock();
	}
	/*-------------*/

	*last_irq_ptr = new_fd;
	last_irq_ptr = &new_fd->next;

	irq_unlock(flags);

	/* This calls activate_fd, so it has to be outside the critical
	 * section.
	 */
	maybe_sigio_broken(fd, type);

	return(0);

 out_unlock:
	irq_unlock(flags);
 out_kfree:
	kfree(new_fd);
 out:
	return(err);
}

static void free_irq_by_cb(int (*test)(struct irq_fd *, void *), void *arg)
{
	unsigned long flags;

	flags = irq_lock();
 	os_free_irq_by_cb(test, arg, active_fds, &last_irq_ptr);
	irq_unlock(flags);
}

struct irq_and_dev {
	int irq;
	void *dev;
};

static int same_irq_and_dev(struct irq_fd *irq, void *d)
{
	struct irq_and_dev *data = d;

	return((irq->irq == data->irq) && (irq->id == data->dev));
}

void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
{
	struct irq_and_dev data = ((struct irq_and_dev) { .irq  = irq,
							  .dev  = dev });

	free_irq_by_cb(same_irq_and_dev, &data);
}

static int same_fd(struct irq_fd *irq, void *fd)
{
	return(irq->fd == *((int *) fd));
}

void free_irq_by_fd(int fd)
{
	free_irq_by_cb(same_fd, &fd);
}

static struct irq_fd *find_irq_by_fd(int fd, int irqnum, int *index_out)
{
	struct irq_fd *irq;
	int i = 0;
	int fdi;

	for(irq=active_fds; irq != NULL; irq = irq->next){
		if((irq->fd == fd) && (irq->irq == irqnum)) break;
		i++;
	}
	if(irq == NULL){
		printk("find_irq_by_fd doesn't have descriptor %d\n", fd);
		goto out;
	}
	fdi = os_get_pollfd(i);
	if((fdi != -1) && (fdi != fd)){
		printk("find_irq_by_fd - mismatch between active_fds and "
		       "pollfds, fd %d vs %d, need %d\n", irq->fd,
		       fdi, fd);
		irq = NULL;
		goto out;
	}
	*index_out = i;
 out:
	return(irq);
}

void reactivate_fd(int fd, int irqnum)
{
	struct irq_fd *irq;
	unsigned long flags;
	int i;

	flags = irq_lock();
	irq = find_irq_by_fd(fd, irqnum, &i);
	if(irq == NULL){
		irq_unlock(flags);
		return;
	}
	os_set_pollfd(i, irq->fd);
	irq_unlock(flags);

	/* This calls activate_fd, so it has to be outside the critical
	 * section.
	 */
	maybe_sigio_broken(fd, irq->type);
}

void deactivate_fd(int fd, int irqnum)
{
	struct irq_fd *irq;
	unsigned long flags;
	int i;

	flags = irq_lock();
	irq = find_irq_by_fd(fd, irqnum, &i);
	if(irq == NULL)
		goto out;
	os_set_pollfd(i, -1);
 out:
	irq_unlock(flags);
}

int deactivate_all_fds(void)
{
	struct irq_fd *irq;
	int err;

	for(irq=active_fds;irq != NULL;irq = irq->next){
		err = os_clear_fd_async(irq->fd);
		if(err)
			return(err);
	}
	/* If there is a signal already queued, after unblocking ignore it */
	os_set_ioignore();

	return(0);
}

void forward_interrupts(int pid)
{
	struct irq_fd *irq;
	unsigned long flags;
	int err;

	flags = irq_lock();
	for(irq=active_fds;irq != NULL;irq = irq->next){
		err = os_set_owner(irq->fd, pid);
		if(err < 0){
			/* XXX Just remove the irq rather than
			 * print out an infinite stream of these
			 */
			printk("Failed to forward %d to pid %d, err = %d\n",
			       irq->fd, pid, -err);
		}

		irq->pid = pid;
	}
	irq_unlock(flags);
}

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-file-style: "linux"
 * End:
 */