From: "Jason A. Donenfeld" <Jason@zx2c4.com> stable inclusion from stable-v5.10.119 commit 9b0e0e27140d007241772cadc7df1e05292f465d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BB Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit a3f9e8910e1584d7725ef7d5ac870920d42d0bb4 upstream. The only time that we need to wake up /dev/random writers on RNDCLEARPOOL/RNDZAPPOOL is when we're changing from a value that is greater than or equal to POOL_MIN_BITS to zero, because if we're changing from below POOL_MIN_BITS to zero, the writers are already unblocked. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- drivers/char/random.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 35991d87d619..6a5da2fe2305 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1582,7 +1582,7 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; - if (xchg(&input_pool.entropy_count, 0)) { + if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) { wake_up_interruptible(&random_write_wait); kill_fasync(&fasync, SIGIO, POLL_OUT); } -- 2.20.1