From: Juergen Gross jgross@suse.com
[ Upstream commit 51c23bd691c0f1fb95b29731c356c6fd69925d17 ]
When unbinding a user event channel, the related handler might be called a last time in case the kernel was built with CONFIG_DEBUG_SHIRQ. This might cause a WARN() in the handler.
Avoid that by adding an "unbinding" flag to struct user_event which will short circuit the handler.
Fixes: 9e90e58c11b7 ("xen: evtchn: Allow shared registration of IRQ handers") Reported-by: Demi Marie Obenour demi@invisiblethingslab.com Tested-by: Demi Marie Obenour demi@invisiblethingslab.com Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Oleksandr Tyshchenko oleksandr_tyshchenko@epam.com Link: https://lore.kernel.org/r/20240313071409.25913-2-jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/evtchn.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index 59717628ca42b..f6a2216c2c870 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -85,6 +85,7 @@ struct user_evtchn { struct per_user_data *user; evtchn_port_t port; bool enabled; + bool unbinding; };
static void evtchn_free_ring(evtchn_port_t *ring) @@ -164,6 +165,10 @@ static irqreturn_t evtchn_interrupt(int irq, void *data) struct per_user_data *u = evtchn->user; unsigned int prod, cons;
+ /* Handler might be called when tearing down the IRQ. */ + if (evtchn->unbinding) + return IRQ_HANDLED; + WARN(!evtchn->enabled, "Interrupt for port %u, but apparently not enabled; per-user %p\n", evtchn->port, u); @@ -421,6 +426,7 @@ static void evtchn_unbind_from_user(struct per_user_data *u,
BUG_ON(irq < 0);
+ evtchn->unbinding = true; unbind_from_irqhandler(irq, evtchn);
del_evtchn(u, evtchn);