lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

xen: save previous spinlock when blocking

Browse Source 
A spinlock can be interrupted while spinning, so make sure we preserve
the previous lock of interest if we're taking a lock from within an
interrupt handler.

We also need to deal with the case where the blocking path gets
interrupted between testing to see if the lock is free and actually
blocking.  If we get interrupted there and end up in the state where
the lock is free but the irq isn't pending, then we'll block
indefinitely in the hypervisor.  This fix is to make sure that any
nested lock-takers will always leave the irq pending if there's any
chance the outer lock became free.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge
2008-08-20 17:02:18 -07:00
committed by Ingo Molnar
parent 7708ad64a2
commit 168d2f464a
3 changed files with 77 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/xen/events.c
View File

@@ -164,6 +164,12 @@ static inline void set_evtchn(int port)
sync_set_bit(port, &s->evtchn_pending[0]);
}
static inline int test_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
return sync_test_bit(port, &s->evtchn_pending[0]);
}
/**
* notify_remote_via_irq - send event to remote end of event channel via irq
@@ -732,6 +738,25 @@ void xen_clear_irq_pending(int irq)
clear_evtchn(evtchn);
}
void xen_set_irq_pending(int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
set_evtchn(evtchn);
}
bool xen_test_irq_pending(int irq)
{
int evtchn = evtchn_from_irq(irq);
bool ret = false;
if (VALID_EVTCHN(evtchn))
ret = test_evtchn(evtchn);
return ret;
}
/* Poll waiting for an irq to become pending. In the usual case, the
irq will be disabled so it won't deliver an interrupt. */
void xen_poll_irq(int irq)