[PATCH v3 2/6] virtio_ccw: always take irq_lock in the classic interrupt handler
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COLD34d
IN LINUX-NEXT
From: Karl Mehltretter <hidden>
Date: 2026-09-08 05:39:43
Also in:
kvm, linux-input, linux-remoteproc, linux-s390, linux-um, lkml, platform-driver-x86
Subsystem:
s390 architecture, the rest, virtio drivers for s390 · Maintainers:
Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Cornelia Huck, Halil Pasic, Eric Farman
Queued in linux-next as 48a355cf5b38 on 2026-09-08.
virtio_ccw_int_handler() takes vcdev->irq_lock around its
vring_interrupt() calls only when VIRTIO_HARDEN_NOTIFICATION is enabled.
The virtio shutdown path calls synchronize_cbs() even when notification
hardening is disabled. virtio_reset_device() now does so after the
transport reset too.
For classic interrupts, synchronize_cbs() takes vcdev->irq_lock for
writing, but the interrupt handler does not take the matching read
lock in that configuration. synchronize_cbs() can return while a
callback is still running.
Take the read lock unconditionally so the write side can synchronize
with the callbacks.
Fixes: 8bd2fa086a04 ("virtio: break and reset virtio devices on device_shutdown()")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <redacted>
---
drivers/s390/virtio/virtio_ccw.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index b90299205698..552d77998012 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c@@ -1204,13 +1204,11 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vcdev->err = -EIO; } virtio_ccw_check_activity(vcdev, activity); -#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION /* * Paired with virtio_ccw_synchronize_cbs() and interrupts are * disabled here. */ read_lock(&vcdev->irq_lock); -#endif for_each_set_bit(i, indicators(vcdev), sizeof(*indicators(vcdev)) * BITS_PER_BYTE) { /* The bit clear must happen before the vring kick. */
@@ -1219,9 +1217,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vq = virtio_ccw_vq_by_ind(vcdev, i); vring_interrupt(0, vq); } -#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION read_unlock(&vcdev->irq_lock); -#endif if (test_bit(0, indicators2(vcdev))) { virtio_config_changed(&vcdev->vdev); clear_bit(0, indicators2(vcdev));
--
2.39.5 (Apple Git-154)