diff options
| author | Juergen Gross <jgross@suse.com> | 2018-10-01 07:57:42 +0200 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2018-10-24 10:18:04 +0200 |
| commit | a856531951dc8094359dfdac21d59cee5969c18e (patch) | |
| tree | 3e87ca7c1afe1453d3aaac82b1ef4eae3114bf88 /net/sched/sch_fq.c | |
| parent | 2ac2a7d4d9ff4e01e36f9c3d116582f6f655ab47 (diff) | |
xen: make xen_qlock_wait() nestable
xen_qlock_wait() isn't safe for nested calls due to interrupts. A call
of xen_qlock_kick() might be ignored in case a deeper nesting level
was active right before the call of xen_poll_irq():
CPU 1: CPU 2:
spin_lock(lock1)
spin_lock(lock1)
-> xen_qlock_wait()
-> xen_clear_irq_pending()
Interrupt happens
spin_unlock(lock1)
-> xen_qlock_kick(CPU 2)
spin_lock_irqsave(lock2)
spin_lock_irqsave(lock2)
-> xen_qlock_wait()
-> xen_clear_irq_pending()
clears kick for lock1
-> xen_poll_irq()
spin_unlock_irq_restore(lock2)
-> xen_qlock_kick(CPU 2)
wakes up
spin_unlock_irq_restore(lock2)
IRET
resumes in xen_qlock_wait()
-> xen_poll_irq()
never wakes up
The solution is to disable interrupts in xen_qlock_wait() and not to
poll for the irq in case xen_qlock_wait() is called in nmi context.
Cc: stable@vger.kernel.org
Cc: Waiman.Long@hp.com
Cc: peterz@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'net/sched/sch_fq.c')
0 files changed, 0 insertions, 0 deletions