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uml: irq locking commentary

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Locking commentary.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Dike 2007-05-06 14:51:27 -07:00 committed by Linus Torvalds
parent 1d1497e1f9
commit d973a77bdb
1 changed files with 15 additions and 0 deletions
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15
arch/um/kernel/irq.c
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@ -78,6 +78,14 @@ int show_interrupts(struct seq_file *p, void *v)
return 0;
}
/*
* This list is accessed under irq_lock, except in sigio_handler,
* where it is safe from being modified. IRQ handlers won't change it -
* if an IRQ source has vanished, it will be freed by free_irqs just
* before returning from sigio_handler. That will process a separate
* list of irqs to free, with its own locking, coming back here to
* remove list elements, taking the irq_lock to do so.
*/
static struct irq_fd *active_fds = NULL;
static struct irq_fd **last_irq_ptr = &active_fds;
@ -243,6 +251,7 @@ void free_irq_by_fd(int fd)
free_irq_by_cb(same_fd, &fd);
}
/* Must be called with irq_lock held */
static struct irq_fd *find_irq_by_fd(int fd, int irqnum, int *index_out)
{
struct irq_fd *irq;
@ -308,6 +317,12 @@ void deactivate_fd(int fd, int irqnum)
ignore_sigio_fd(fd);
}
/*
* Called just before shutdown in order to provide a clean exec
* environment in case the system is rebooting. No locking because
* that would cause a pointless shutdown hang if something hadn't
* released the lock.
*/
int deactivate_all_fds(void)
{
struct irq_fd *irq;