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Current hwrng core supports to register multiple hwrng devices, and there is only one device really works in the same time. QEMU alsu supports to have multiple virtio-rng backends. This patch changes virtio-rng driver to support multiple virtio-rng devices. ]# cat /sys/class/misc/hw_random/rng_available virtio...

Current hwrng core supports to register multiple hwrng devices, and there is only one device really works in the same time. QEMU alsu supports to have multiple virtio-rng backends. This patch changes virtio-rng driver to support multiple virtio-rng devices. ]# cat /sys/class/misc/hw_random/rng_available virtio...

....com.au> > > current_rng holds one reference, and we bump it every time we want > to do a read from it. > > This means we only hold the rng_mutex to grab or drop a reference, > so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't > block on read of /dev/hwrng. > > Using a kref is overkill (we're always under the rng_mutex), but > a standard pattern. > > This also solves the problem that the hwrng_fillfn thread was > accessing current_rng without a lock, which could change (eg. to NULL) > underneath it. > > V2: reduce re...

....com.au> > > current_rng holds one reference, and we bump it every time we want > to do a read from it. > > This means we only hold the rng_mutex to grab or drop a reference, > so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't > block on read of /dev/hwrng. > > Using a kref is overkill (we're always under the rng_mutex), but > a standard pattern. > > This also solves the problem that the hwrng_fillfn thread was > accessing current_rng without a lock, which could change (eg. to NULL) > underneath it. > > V2: reduce re...

Amos Kong <akong at redhat.com> writes: > We got a warning in boot stage when above set_current_rng() is executed, > it can be fixed by init rng->ref in hwrng_init(). > > > @@ -166,6 +169,8 @@ static inline int hwrng_init(struct hwrng *rng) > if (current_quality > 0 && !hwrng_fill) > start_khwrngd(); > > + kref_init(&rng->ref); > + > return 0; > } OK, I folded this...

Amos Kong <akong at redhat.com> writes: > We got a warning in boot stage when above set_current_rng() is executed, > it can be fixed by init rng->ref in hwrng_init(). > > > @@ -166,6 +169,8 @@ static inline int hwrng_init(struct hwrng *rng) > if (current_quality > 0 && !hwrng_fill) > start_khwrngd(); > > + kref_init(&rng->ref); > + > return 0; > } OK, I folded this...

current_rng holds one reference, and we bump it every time we want to do a read from it. This means we only hold the rng_mutex to grab or drop a reference, so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't block on read of /dev/hwrng. Using a kref is overkill (we're always under the rng_mutex), but a standard pattern. This also solves the problem that the hwrng_fillfn thread was accessing current_rng without a lock, which could change (eg. to NULL) underneath it. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au&...

...Rusty Russell <rusty at rustcorp.com.au> current_rng holds one reference, and we bump it every time we want to do a read from it. This means we only hold the rng_mutex to grab or drop a reference, so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't block on read of /dev/hwrng. Using a kref is overkill (we're always under the rng_mutex), but a standard pattern. This also solves the problem that the hwrng_fillfn thread was accessing current_rng without a lock, which could change (eg. to NULL) underneath it. V2: reduce reference count in signal_pending path Signed-...

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My original was pain, Rusty posted a real fix. This patchset fixed two issue in v1, and tested by my 6+ cases. | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device fr...

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My original was pain, Rusty posted a real fix. This patchset fixed two issue in v1, and tested by my 6+ cases. | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device fr...

...Rusty Russell <rusty at rustcorp.com.au> current_rng holds one reference, and we bump it every time we want to do a read from it. This means we only hold the rng_mutex to grab or drop a reference, so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't block on read of /dev/hwrng. Using a kref is overkill (we're always under the rng_mutex), but a standard pattern. This also solves the problem that the hwrng_fillfn thread was accessing current_rng without a lock, which could change (eg. to NULL) underneath it. v4: decrease last reference for triggering the cleanup v3:...

...Rusty Russell <rusty at rustcorp.com.au> current_rng holds one reference, and we bump it every time we want to do a read from it. This means we only hold the rng_mutex to grab or drop a reference, so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't block on read of /dev/hwrng. Using a kref is overkill (we're always under the rng_mutex), but a standard pattern. This also solves the problem that the hwrng_fillfn thread was accessing current_rng without a lock, which could change (eg. to NULL) underneath it. v4: decrease last reference for triggering the cleanup v3:...

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 rn...

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 rn...

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 rn...

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 rn...

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 rn...

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 rn...

Amos Kong <akong at redhat.com> writes: > I started a QEMU (non-smp) guest with one virtio-rng device, and read > random data from /dev/hwrng by dd: > > # dd if=/dev/hwrng of=/dev/null & > > In the same time, if I check hwrng attributes from sysfs by cat: > > # cat /sys/class/misc/hw_random/rng_* > > The cat process always gets stuck with slow backend (5 k/s), if we > use a quick backend (1.2 M/s), the ca...

Amos Kong <akong at redhat.com> writes: > I started a QEMU (non-smp) guest with one virtio-rng device, and read > random data from /dev/hwrng by dd: > > # dd if=/dev/hwrng of=/dev/null & > > In the same time, if I check hwrng attributes from sysfs by cat: > > # cat /sys/class/misc/hw_random/rng_* > > The cat process always gets stuck with slow backend (5 k/s), if we > use a quick backend (1.2 M/s), the ca...