When I hotunplug a busy virtio-rng device or try to access
hwrng attributes in non-smp guest, it gets stuck.
My hotplug tests:
| test 0:
| hotunplug rng device from qemu monitor
|
| test 1:
| guest) # dd if=/dev/hwrng of=/dev/null &
| hotunplug rng device from qemu monitor
|
| test 2:
| guest) # dd if=/dev/random of=/dev/null &
| hotunplug rng device from qemu monitor
|
| test 4:
| guest) # dd if=/dev/hwrng of=/dev/null &
| cat /sys/devices/virtual/misc/hw_random/rng_*
|
| test 5:
| guest) # dd if=/dev/hwrng of=/dev/null
| cancel dd process after 10 seconds
| guest) # dd if=/dev/hwrng of=/dev/null &
| hotunplug rng device from qemu monitor
|
| test 6:
| use a fifo as rng backend, execute test 0 ~ 5 with no input of fifo
V5: reset cleanup_done flag, drop redundant init of reference count, use
compiler barrier to prevent recording.
V4: update patch 4 to fix corrupt, decrease last reference for triggering
the cleanup, fix unregister race pointed by Herbert
V3: initialize kref to 1
V2: added patch 2 to fix a deadlock, update current patch 3 to fix reference
counting issue
Amos Kong (1):
hw_random: move some code out mutex_lock for avoiding underlying
deadlock
Rusty Russell (5):
hw_random: place mutex around read functions and buffers.
hw_random: use reference counts on each struct hwrng.
hw_random: fix unregister race.
hw_random: don't double-check old_rng.
hw_random: don't init list element we're about to add to list.
drivers/char/hw_random/core.c | 173 ++++++++++++++++++++++++++++++------------
include/linux/hw_random.h | 3 +
2 files changed, 126 insertions(+), 50 deletions(-)
--
1.9.3
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