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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: ff6a17989c ("Epoll based IRQ controller")
Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Jouni Malinen 2019-05-06 14:39:35 +02:00 committed by Richard Weinberger
parent 4b972a01a7
commit bebe4681d0
2 changed files with 48 additions and 8 deletions
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52
arch/um/drivers/chan_kern.c
View File

@ -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 (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 (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);

4
arch/um/kernel/irq.c
View File

@ -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)