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2018-10-05hwrng: core - document the quality fieldMichael S. Tsirkin1-1/+2
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" <dgilbert@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2016-11-21hwrng: Make explicit that max >= 32 alwaysPrasannaKumar Muralidharan1-2/+1
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 <prasannatsmkumar@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2016-08-24hwrng: core - Improve description of the ->read() interfaceDaniel Thompson1-1/+3
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 <daniel.thompson@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-03-16hwrng: add devm_* interfacesDmitry Torokhov1-0/+4
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 <dmitry.torokhov@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-12-26hwrng: core - Use struct completion for cleanup_doneHerbert Xu1-1/+2
There is no point in doing a manual completion for cleanup_done when struct completion fits in perfectly. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-12-22hwrng: fix unregister race.Rusty Russell1-0/+1
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 <rusty@rustcorp.com.au> Signed-off-by: Amos Kong <akong@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-12-22hwrng: use reference counts on each struct hwrng.Rusty Russell1-0/+2
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@rustcorp.com.au> Signed-off-by: Amos Kong <akong@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-15hwrng: add per-device entropy deratingTorsten Duwe1-0/+3
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 <duwe@suse.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Acked-by: H. Peter Anvin <hpa@zytor.com>
2014-07-15random: add_hwgenerator_randomness() for feeding entropy from devicesTorsten Duwe1-0/+2
This patch adds an interface to the random pool for feeding entropy in-kernel. Signed-off-by: Torsten Duwe <duwe@suse.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Acked-by: H. Peter Anvin <hpa@zytor.com>
2011-05-25hwrng: fix spelling mistake in header commentSasha Levin1-1/+1
Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Matt Mackall <mpm@selenic.com> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-12-01hwrng: core - Replace u32 in driver API with byte arrayIan Molton1-2/+5
This patch implements a new method by which hw_random hardware drivers can pass data to the core more efficiently, using a shared buffer. The old methods have been retained as a compatability layer until all the drivers have been updated. Signed-off-by: Ian Molton <ian.molton@collabora.co.uk> Acked-by: Matt Mackall <mpm@selenic.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-04-30Remove "#ifdef __KERNEL__" checks from unexported headersRobert P. J. Day1-2/+0
Remove the "#ifdef __KERNEL__" tests from unexported header files in linux/include whose entire contents are wrapped in that preprocessor test. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-19PM: Remove destroy_suspended_device()Rafael J. Wysocki1-9/+1
After 2.6.24 there was a plan to make the PM core acquire all device semaphores during a suspend/hibernation to protect itself from concurrent operations involving device objects. That proved to be too heavy-handed and we found a better way to achieve the goal, but before it happened, we had introduced the functions device_pm_schedule_removal() and destroy_suspended_device() to allow drivers to "safely" destroy a suspended device and we had adapted some drivers to use them. Now that these functions are no longer necessary, it seems reasonable to remove them and modify their users to use the normal device unregistration instead. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-02-05HWRNG: add possibility to remove hwrng devices during suspend/resumeRafael J. Wysocki1-1/+9
Make it possible to unregister a Hardware Random Number Generator device object in a safe way during a suspend/resume cycle. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Michael Buesch <mb@bu3sch.de> Cc: Michael Buesch <mb@bu3sch.de> Cc: Pavel Machek <pavel@ucw.cz> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Len Brown <lenb@kernel.org> Cc: Greg KH <greg@kroah.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-11[HWRNG]: move status polling loop to data_present callbacksPatrick McHardy1-1/+1
Handle waiting for new random within the drivers themselves, this allows to use better suited timeouts for the individual rngs. Signed-off-by: Patrick McHardy <kaber@trash.net> Acked-by: Michael Buesch <mb@bu3sch.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2006-06-26[PATCH] Add new generic HW RNG coreMichael Buesch1-0/+50
Signed-off-by: Michael Buesch <mb@bu3sch.de> Cc: Jeff Garzik <jeff@garzik.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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