36cb649442
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>
123 lines
3.1 KiB
C
123 lines
3.1 KiB
C
/*
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* Copyright (c) 2015 Qualcomm Atheros, Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <linux/hw_random.h>
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#include <linux/kthread.h>
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#include "ath9k.h"
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#include "hw.h"
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#include "ar9003_phy.h"
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static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
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{
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int i, j;
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u32 v1, v2, rng_last = sc->rng_last;
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struct ath_hw *ah = sc->sc_ah;
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ath9k_ps_wakeup(sc);
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REG_RMW_FIELD(ah, AR_PHY_TEST, AR_PHY_TEST_BBB_OBS_SEL, 1);
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REG_CLR_BIT(ah, AR_PHY_TEST, AR_PHY_TEST_RX_OBS_SEL_BIT5);
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REG_RMW_FIELD(ah, AR_PHY_TEST_CTL_STATUS, AR_PHY_TEST_CTL_RX_OBS_SEL, 0);
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for (i = 0, j = 0; i < buf_size; i++) {
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v1 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
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v2 = REG_READ(ah, AR_PHY_TST_ADC) & 0xffff;
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/* wait for data ready */
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if (v1 && v2 && rng_last != v1 && v1 != v2 && v1 != 0xffff &&
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v2 != 0xffff)
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buf[j++] = (v1 << 16) | v2;
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rng_last = v2;
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}
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ath9k_ps_restore(sc);
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sc->rng_last = rng_last;
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return j << 2;
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}
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static u32 ath9k_rng_delay_get(u32 fail_stats)
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{
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u32 delay;
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if (fail_stats < 100)
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delay = 10;
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else if (fail_stats < 105)
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delay = 1000;
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else
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delay = 10000;
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return delay;
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}
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static int ath9k_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
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{
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struct ath_softc *sc = container_of(rng, struct ath_softc, rng_ops);
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u32 fail_stats = 0, word;
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int bytes_read = 0;
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for (;;) {
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if (max & ~3UL)
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bytes_read = ath9k_rng_data_read(sc, buf, max >> 2);
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if ((max & 3UL) && ath9k_rng_data_read(sc, &word, 1)) {
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memcpy(buf + bytes_read, &word, max & 3UL);
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bytes_read += max & 3UL;
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memzero_explicit(&word, sizeof(word));
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}
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if (!wait || !max || likely(bytes_read) || fail_stats > 110)
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break;
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if (hwrng_msleep(rng, ath9k_rng_delay_get(++fail_stats)))
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break;
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}
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if (wait && !bytes_read && max)
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bytes_read = -EIO;
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return bytes_read;
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}
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void ath9k_rng_start(struct ath_softc *sc)
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{
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static atomic_t serial = ATOMIC_INIT(0);
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struct ath_hw *ah = sc->sc_ah;
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if (sc->rng_ops.read)
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return;
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if (!AR_SREV_9300_20_OR_LATER(ah))
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return;
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snprintf(sc->rng_name, sizeof(sc->rng_name), "ath9k_%u",
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(atomic_inc_return(&serial) - 1) & U16_MAX);
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sc->rng_ops.name = sc->rng_name;
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sc->rng_ops.read = ath9k_rng_read;
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sc->rng_ops.quality = 320;
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if (devm_hwrng_register(sc->dev, &sc->rng_ops))
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sc->rng_ops.read = NULL;
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}
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void ath9k_rng_stop(struct ath_softc *sc)
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{
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if (sc->rng_ops.read) {
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devm_hwrng_unregister(sc->dev, &sc->rng_ops);
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sc->rng_ops.read = NULL;
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}
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}
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