Commit d973a77b authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
Browse files

uml: irq locking commentary



Locking commentary.
Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d1497e1
......@@ -78,6 +78,14 @@ skip:
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;
......
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