virtio: rtc: time out alarm requests

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RTC class operations run with rtc_device.ops_lock held. The virtio RTC
alarm requests currently wait without a timeout for the device to return
their requestq buffers.

On surprise removal, virtio-pci marks the virtqueues broken before
unregistering the virtio device. If an alarm request is waiting when the
device stops responding, viortc_remove() blocks in viortc_class_stop()
while trying to acquire ops_lock. The request cannot complete and device
removal hangs until the waiting task is signalled.

Use the same 60-second timeout as clock read requests for alarm reads,
alarm programming, and alarm interrupt enable requests. The existing
message reference counting keeps a timed-out request alive until a late
response or device teardown.

Fixes: 9d4f22fd56 ("virtio_rtc: Add RTC class driver")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: GuoHan Zhao <zhaoguohan@kylinos.cn>
Reviewed-by: Peter Hilber <peter.hilber@oss.qualcomm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260714024352.71307-1-zhaoguohan@kylinos.cn>

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GuoHan Zhao 2026-07-14 10:43:52 +08:00 • committed by Michael S. Tsirkin

parent 2de8556576

commit 68e00d9212

1 changed files with 7 additions and 7 deletions

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drivers/virtio/virtio_rtc_driver.c

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