user/sven/linux.git/include/linux/hw_random.h, branch v5.8

docs: admin-guide: add a series of orphaned documents

2019-07-15T14:03:02Z

There are lots of documents that belong to the admin-guide but are on random places (most under Documentation root dir). Move them to the admin guide. Signed-off-by: Mauro Carvalho Chehab Acked-by: Alexandre Belloni Acked-by: Bartlomiej Zolnierkiewicz

hwrng: core - document the quality field

2018-10-05T02:16:56Z

quality field is currently documented as being 'per mill'. In fact the math involved is: add_hwgenerator_randomness((void *)rng_fillbuf, rc, rc * current_quality * 8 >> 10); thus the actual definition is "bits of entropy per 1024 bits of input". The current documentation seems to have confused multiple people in the past, let's fix the documentation to match code. An alternative is to change core to match driver expectations, replacing rc * current_quality * 8 >> 10 with rc * current_quality / 1000 but that has performance costs, so probably isn't a good option. Fixes: 0f734e6e768 ("hwrng: add per-device entropy derating") Reported-by: "Dr. David Alan Gilbert" Signed-off-by: Michael S. Tsirkin Signed-off-by: Herbert Xu

hwrng: Make explicit that max >= 32 always

2016-11-21T14:50:45Z

As hw_random core calls ->read with max > 32 or more, make it explicit. Also remove checks involving 'max' being less than 8. Signed-off-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu

hwrng: core - Improve description of the ->read() interface

2016-08-24T13:04:48Z

Currently, very few RNG drivers support single byte reads using the ->read() interface. Of the 14 drivers in drivers/char/hw_random that support this interface only three of these actually support max == 1. The other behaviours vary between return 0, return 2, return 4 and return -EIO). This is not a problem in practice because the core hw_random code never performs a read shorter than 16 bytes. The documentation for this function already contrains the alignment of the buffer pointer, so let's also guarantee that the buffer is at least as large as its alignment. This constraint is intended to be the weakest guarantee neccessary to allow driver writers to safely simplify their code. Signed-off-by: Daniel Thompson Signed-off-by: Herbert Xu

hwrng: add devm_* interfaces

2015-03-16T10:45:54Z

This change adds devm_hwrng_register and devm_hwrng_unregister which use can simplify error unwinding and unbinding code paths in device drivers. Signed-off-by: Dmitry Torokhov Signed-off-by: Herbert Xu

hwrng: core - Use struct completion for cleanup_done

2014-12-25T21:33:34Z

There is no point in doing a manual completion for cleanup_done when struct completion fits in perfectly. Signed-off-by: Herbert Xu

hwrng: fix unregister race.

2014-12-22T12:02:40Z

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.

2014-12-22T12:02:39Z

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

hwrng: add per-device entropy derating

2014-07-15T08:49:40Z

This patch introduces a derating factor to struct hwrng for the random bits going into the kernel input pool, and a common default derating for drivers which do not specify one. Signed-off-by: Torsten Duwe Signed-off-by: Theodore Ts'o Acked-by: H. Peter Anvin

random: add_hwgenerator_randomness() for feeding entropy from devices

2014-07-15T08:49:40Z

This patch adds an interface to the random pool for feeding entropy in-kernel. Signed-off-by: Torsten Duwe Signed-off-by: Theodore Ts'o Acked-by: H. Peter Anvin