Commit bebe4681 authored by Jouni Malinen's avatar Jouni Malinen Committed by Richard Weinberger
Browse files

um: Fix IRQ controller regression on console read 



The conversion of UML to use epoll based IRQ controller claimed that
clone_one_chan() can safely call um_free_irq() while starting to ignore
the delay_free_irq parameter that explicitly noted that the IRQ cannot
be freed because this is being called from chan_interrupt(). This
resulted in free_irq() getting called in interrupt context ("Trying to
free IRQ 6 from IRQ context!").

Fix this by restoring previously used delay_free_irq processing.

Fixes: ff6a1798 ("Epoll based IRQ controller")
Signed-off-by: default avatarJouni Malinen <j@w1.fi>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 4b972a01

arch/um/drivers/chan_kern.c

+44 −8
Original line number Diff line number Diff line
@@ -171,19 +171,55 @@ int enable_chan(struct line *line) 
	return err;

}



/* Items are added in IRQ context, when free_irq can't be called, and

 * removed in process context, when it can.

 * This handles interrupt sources which disappear, and which need to

 * be permanently disabled.  This is discovered in IRQ context, but

 * the freeing of the IRQ must be done later.

 */

static DEFINE_SPINLOCK(irqs_to_free_lock);

static LIST_HEAD(irqs_to_free);



void free_irqs(void)

{

	struct chan *chan;

	LIST_HEAD(list);

	struct list_head *ele;

	unsigned long flags;



	spin_lock_irqsave(&irqs_to_free_lock, flags);

	list_splice_init(&irqs_to_free, &list);

	spin_unlock_irqrestore(&irqs_to_free_lock, flags);



	list_for_each(ele, &list) {

		chan = list_entry(ele, struct chan, free_list);



		if (chan->input && chan->enabled)

			um_free_irq(chan->line->driver->read_irq, chan);

		if (chan->output && chan->enabled)

			um_free_irq(chan->line->driver->write_irq, chan);

		chan->enabled = 0;

	}

}



static void close_one_chan(struct chan *chan, int delay_free_irq)

{

	unsigned long flags;



	if (!chan->opened)

		return;



    /* we can safely call free now - it will be marked

     *  as free and freed once the IRQ stopped processing

     */

	if (delay_free_irq) {

		spin_lock_irqsave(&irqs_to_free_lock, flags);

		list_add(&chan->free_list, &irqs_to_free);

		spin_unlock_irqrestore(&irqs_to_free_lock, flags);

	} else {

		if (chan->input && chan->enabled)

			um_free_irq(chan->line->driver->read_irq, chan);

		if (chan->output && chan->enabled)

			um_free_irq(chan->line->driver->write_irq, chan);

		chan->enabled = 0;

	}

	if (chan->ops->close != NULL)

		(*chan->ops->close)(chan->fd, chan->data);

arch/um/kernel/irq.c

+4 −0
Original line number Diff line number Diff line
@@ -21,6 +21,8 @@ 
#include <irq_user.h>





extern void free_irqs(void);



/* When epoll triggers we do not know why it did so

 * we can also have different IRQs for read and write.

 * This is why we keep a small irq_fd array for each fd -
@@ -100,6 +102,8 @@ void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) 
			}

		}

	}



	free_irqs();

}



static int assign_epoll_events_to_irq(struct irq_entry *irq_entry)

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