| Message ID | 878skypjrh.fsf@nanos.tec.linutronix.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 8645e56a4ad6dcbf504872db7f14a2f67db88ef2 |
| Headers | show |
| Series | [V2] xen: Enable interrupts when calling _cond_resched() | expand |
On 19.02.20 18:30, Thomas Gleixner wrote: > xen_maybe_preempt_hcall() is called from the exception entry point > xen_do_hypervisor_callback with interrupts disabled. > > _cond_resched() evades the might_sleep() check in cond_resched() which > would have caught that and schedule_debug() unfortunately lacks a check > for irqs_disabled(). > > Enable interrupts around the call and use cond_resched() to catch future > issues. > > Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted") > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
--- a/drivers/xen/preempt.c +++ b/drivers/xen/preempt.c @@ -33,7 +33,9 @@ asmlinkage __visible void xen_maybe_pree * cpu. */ __this_cpu_write(xen_in_preemptible_hcall, false); - _cond_resched(); + local_irq_enable(); + cond_resched(); + local_irq_disable(); __this_cpu_write(xen_in_preemptible_hcall, true); } }
xen_maybe_preempt_hcall() is called from the exception entry point xen_do_hypervisor_callback with interrupts disabled. _cond_resched() evades the might_sleep() check in cond_resched() which would have caught that and schedule_debug() unfortunately lacks a check for irqs_disabled(). Enable interrupts around the call and use cond_resched() to catch future issues. Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- V2: Put local_irq_disable() where it belongs. --- drivers/xen/preempt.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)