linux/drivers/char
Jason A. Donenfeld 9148de3196 random: reseed in delayed work rather than on-demand
Currently, we reseed when random bytes are requested, if the current
seed is too old. Since random bytes can be requested from all contexts,
including hard IRQ, this means sometimes we wind up adding a bit of
latency to hard IRQ. This was so much of a problem on s390x that now
s390x just doesn't provide its architectural RNG from hard IRQ context,
so we miss out in that case.

Instead, let's just schedule a persistent delayed work, so that the
reseeding and potentially expensive operations will always happen from
process context, reducing unexpected latencies from hard IRQ.

This also has the nice effect of accumulating a transcript of random
inputs over time, since it means that we amass more input values. And it
should make future vDSO integration a bit easier.

Cc: Harald Freudenberger <freude@linux.ibm.com>
Cc: Juergen Christ <jchrist@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-18 02:18:10 +01:00
..
agp IOMMU Updates for Linux v5.20/v6.0: 2022-08-06 10:42:38 -07:00
hw_random hw_random: use add_hwgenerator_randomness() for early entropy 2022-11-18 02:18:10 +01:00
ipmi Fix a bunch of little problems in IPMI 2022-10-11 10:42:25 -07:00
mwave char/mwave: Adjust io port register size 2021-12-03 14:27:06 +01:00
pcmcia tty: Make ->set_termios() old ktermios const 2022-08-30 14:22:35 +02:00
tpm tpmdd updates for Linux v6.1-rc1 2022-10-10 13:09:33 -07:00
xilinx_hwicap xilinx_hwicap: cleanup comments 2022-02-25 12:08:57 +01:00
xillybus char: xillybus: fix a refcount leak in cleanup_dev() 2022-04-24 17:30:45 +02:00
adi.c
apm-emulation.c apm-emulation: drop unexpected word "the" in the comments 2022-06-27 16:15:27 +02:00
applicom.c applicom: unneed to initialise statics to 0 2021-12-21 10:14:08 +01:00
applicom.h
bsr.c powerpc/BSR: Make use of the helper macro LIST_HEAD() 2022-02-25 12:10:15 +01:00
ds1620.c
dsp56k.c
dtlk.c
hangcheck-timer.c
hpet.c hpet: remove unused writeq/readq function definitions 2022-02-04 16:45:39 +01:00
Kconfig random: use random.trust_{bootloader,cpu} command line option only 2022-11-18 02:18:10 +01:00
lp.c char: lp: remove redundant initialization of err 2022-06-10 15:29:50 +02:00
Makefile char: remove VR41XX related char driver 2022-07-28 16:12:33 +02:00
mem.c random: restore O_NONBLOCK support 2022-09-23 12:27:57 +02:00
misc.c char: misc: remove usage of list iterator past the loop body 2022-04-24 17:15:12 +02:00
mspec.c
nsc_gpio.c
nvram.c
nwbutton.c
nwbutton.h
nwflash.c
pc8736x_gpio.c
powernv-op-panel.c powerpc/powernv: Fix fall-through warning for Clang 2021-07-13 19:21:41 -05:00
ppdev.c
ps3flash.c powerpc/ps3: make system bus's remove and shutdown callbacks return void 2020-12-04 01:01:22 +11:00
random.c random: reseed in delayed work rather than on-demand 2022-11-18 02:18:10 +01:00
scx200_gpio.c
sonypi.c
tlclk.c
toshiba.c module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
ttyprintk.c char: ttyprintk: register console 2022-04-22 16:24:47 +02:00
uv_mmtimer.c
virtio_console.c Char/Misc and other driver updates for 5.18-rc1 2022-03-28 12:27:35 -07:00