There are two deadlock scenarios that need addressing, which cause
problems when the computer goes to sleep, the interface is set down, and
hwrng_unregister() is called. When the deadlock is hit, sleep is delayed
for tens of seconds, causing it to fail. These scenarios are:
1) The hwrng kthread can't be stopped while it's sleeping, because it
uses msleep_interruptible() which does not react to kthread_stop.
2) A normal user thread can't be interrupted by hwrng_unregister() while
it's sleeping, because hwrng_unregister() is called from elsewhere.
We solve both issues by add a completion object called dying that
fulfils waiters once we have started the process in hwrng_unregister.
At the same time, we should cleanup a common and useless dmesg splat
in the same area.
Cc: <stable@vger.kernel.org>
Reported-by: Gregory Erwin <gregerwin256@gmail.com>
Fixes: fcd09c90c3 ("ath9k: use hw_random API instead of directly dumping into random.c")
Link: https://lore.kernel.org/all/CAO+Okf6ZJC5-nTE_EJUGQtd8JiCkiEHytGgDsFGTEjs0c00giw@mail.gmail.com/
Link: https://lore.kernel.org/lkml/CAO+Okf5k+C+SE6pMVfPf-d8MfVPVq4PO7EY8Hys_DVXtent3HA@mail.gmail.com/
Link: https://bugs.archlinux.org/task/75138
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Acked-by: Kalle Valo <kvalo@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Hardware random number generators are supposed to use the hw_random
framework. This commit turns ath9k's kthread-based design into a proper
hw_random driver.
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Rui Salvaterra <rsalvaterra@gmail.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Rui Salvaterra <rsalvaterra@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220216113323.53332-1-Jason@zx2c4.com
In the worst case, ath9k_rng_stop() may take 10s to stop rng kthread.
The time is too long for users, use wait_event_interruptible_timeout()
instead of msleep_interruptible(), wakup immediately once
kthread_should_stop() is true.
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
The quality of ADC entropy is 10 bits of min-entropy for
a 32-bit value, change '(((x) * 8 * 320) >> 10)' to
'(((x) * 8 * 10) >> 5)' for easier understanding.
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
If no valid ADC randomness output, ath9k rng will continuously
reading ADC, which will cause high CPU load. So increase the
delay to wait for ADC ready.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114261
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
This patch is derived from
commit 6301566e0b ("ath9k: export HW random number generator"),
We evaluated the entropy of the ADC data on QCA9531, QCA9561, QCA955x,
and AR9340, and it has sufficient quality random data (at least 10 bits
and up to 22 bits of min-entropy for a 32-bit value). We conservatively
assume the min-entropy is 10 bits out of 32 bits. Thus, ATH9K_RNG_BUF_SIZE
is set to 320 (u32) i.e., 1.25 kilobytes of data is inserted to fill up
the pool as soon as the entropy counter becomes 896/4096 (set by random.c).
Since ADC was not designed to be a dedicated HW RNG, we do not want to bind
it to /dev/hwrng framework directly. This patch feeds the entropy directly
from the WiFi driver to the input pool. The ADC register output is only
used as a seed for the Linux entropy pool. No conditioning is needed,
since all the conditioning is performed by the pool itself.
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Jason A. Donenfeld