linux-stable.git/drivers/char/hw_random, branch v4.0.2

hwrng: virtio - drop extra empty line

2015-01-26T00:34:23+00:00

makes code look a bit prettier.

Cc: linux-crypto@vger.kernel.org.
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Herbert Xu

hwrng: core - Move hwrng_init call into set_current_rng

2014-12-25T21:33:36+00:00

We always do hwrng_init in set_current_rng.  In fact, our current
reference count system relies on this.  So make this explicit by
moving hwrng_init into set_current_rng.

Signed-off-by: Herbert Xu

hwrng: core - Drop current rng in set_current_rng

2014-12-25T21:33:35+00:00

Rather than having callers of set_current_rng call drop_current_rng,
we can do it directly in set_current_rng.

Signed-off-by: Herbert Xu

hwrng: core - Do not register device opportunistically

2014-12-25T21:33:35+00:00

Currently we only register the device when a valid RNG is added.
However the way it's done is buggy because we test whether there
is a current RNG to determine whether we need to register.  As
the current RNG may be missing due to a reinitialisation error
this can lead to a reregistration of the device.

As the device already has to handle a NULL current RNG anyway,
let's just register the device always and remove the complexity.

Signed-off-by: Herbert Xu

hwrng: core - Fix current_rng init/cleanup race yet again

2014-12-25T21:33:34+00:00

The kref solution is still buggy because we were only focusing
on the register/unregister race.  The same race affects the
setting of current_rng through sysfs.

This patch fixes it by using kref_get_unless_zero.

Signed-off-by: Herbert Xu

hwrng: core - Use struct completion for cleanup_done

2014-12-25T21:33:34+00:00

There is no point in doing a manual completion for cleanup_done
when struct completion fits in perfectly.

Signed-off-by: Herbert Xu

hwrng: don't init list element we're about to add to list.

2014-12-22T12:02:41+00:00

Another interesting anti-pattern.

Signed-off-by: Rusty Russell 
Signed-off-by: Herbert Xu

hwrng: don't double-check old_rng.

2014-12-22T12:02:40+00:00

Interesting anti-pattern.

Signed-off-by: Rusty Russell 
Signed-off-by: Herbert Xu

hwrng: fix unregister race.

2014-12-22T12:02:40+00:00

The previous patch added one potential problem: we can still be
reading from a hwrng when it's unregistered.  Add a wait for zero
in the hwrng_unregister path.

Signed-off-by: Rusty Russell 
Signed-off-by: Amos Kong 
Signed-off-by: Herbert Xu

hwrng: use reference counts on each struct hwrng.

2014-12-22T12:02:39+00:00

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 
Signed-off-by: Amos Kong 
Signed-off-by: Herbert Xu