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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-07-28 18:22:20 +0800 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2022-08-19 18:39:34 +0800 |
| commit | 36cb6494429bd64b27b7ff8b4af56f8e526da2b4 (patch) | |
| tree | 80867f2a756f1d0a7dbe83c752aca8ec61dd96f3 /include/linux/hw_random.h | |
| parent | d74f9340097a881869c4c22ca376654cc2516ecc (diff) | |
| download | lwn-36cb6494429bd64b27b7ff8b4af56f8e526da2b4.tar.gz lwn-36cb6494429bd64b27b7ff8b4af56f8e526da2b4.zip | |
hwrng: core - let sleep be interrupted when unregistering hwrng
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: fcd09c90c3c5 ("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>
Diffstat (limited to 'include/linux/hw_random.h')
| -rw-r--r-- | include/linux/hw_random.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h index aa1d4da03538..77c2885c4c13 100644 --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -50,6 +50,7 @@ struct hwrng { struct list_head list; struct kref ref; struct completion cleanup_done; + struct completion dying; }; struct device; @@ -61,4 +62,6 @@ extern int devm_hwrng_register(struct device *dev, struct hwrng *rng); extern void hwrng_unregister(struct hwrng *rng); extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng); +extern long hwrng_msleep(struct hwrng *rng, unsigned int msecs); + #endif /* LINUX_HWRANDOM_H_ */ |