From: "Jason A. Donenfeld" <Jason@zx2c4.com> stable inclusion from stable-v5.10.102 commit 45102b538a9e0b244ede1007fd8dcc1a0d9a0627 bugzilla: https://gitee.com/openeuler/kernel/issues/I567K6 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 042e293e16e3aa9794ce60c29f5b7b0c8170f933 ] When account() is called, and the amount of entropy dips below random_write_wakeup_bits, we wake up the random writers, so that they can write some more in. However, the RNDZAPENTCNT/RNDCLEARPOOL ioctl sets the entropy count to zero -- a potential reduction just like account() -- but does not unblock writers. This commit adds the missing logic to that ioctl to unblock waiting writers. Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yu Liao <liaoyu15@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- drivers/char/random.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 91ea1fbac6f8..8f29cbc0849e 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1988,7 +1988,10 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; - input_pool.entropy_count = 0; + if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) { + wake_up_interruptible(&random_write_wait); + kill_fasync(&fasync, SIGIO, POLL_OUT); + } return 0; case RNDRESEEDCRNG: if (!capable(CAP_SYS_ADMIN)) -- 2.20.1