From a2cb3d5f043e4cc646c396a3e188a171b38c15a0 Mon Sep 17 00:00:00 2001 From: Miaoqing Pan Date: Fri, 18 Mar 2016 17:54:56 +0800 Subject: [PATCH] ath9k: fix rng high cpu load 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 Signed-off-by: Kalle Valo --- drivers/net/wireless/ath/ath9k/rng.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath9k/rng.c b/drivers/net/wireless/ath/ath9k/rng.c index c9cb2aad7b6f..d38e50f96db7 100644 --- a/drivers/net/wireless/ath/ath9k/rng.c +++ b/drivers/net/wireless/ath/ath9k/rng.c @@ -55,11 +55,26 @@ static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size) return j << 2; } +static u32 ath9k_rng_delay_get(u32 fail_stats) +{ + u32 delay; + + if (fail_stats < 100) + delay = 10; + else if (fail_stats < 105) + delay = 1000; + else + delay = 10000; + + return delay; +} + static int ath9k_rng_kthread(void *data) { int bytes_read; struct ath_softc *sc = data; u32 *rng_buf; + u32 delay, fail_stats = 0; rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL); if (!rng_buf) @@ -69,10 +84,13 @@ static int ath9k_rng_kthread(void *data) bytes_read = ath9k_rng_data_read(sc, rng_buf, ATH9K_RNG_BUF_SIZE); if (unlikely(!bytes_read)) { - msleep_interruptible(10); + delay = ath9k_rng_delay_get(++fail_stats); + msleep_interruptible(delay); continue; } + fail_stats = 0; + /* sleep until entropy bits under write_wakeup_threshold */ add_hwgenerator_randomness((void *)rng_buf, bytes_read, ATH9K_RNG_ENTROPY(bytes_read)); -- 2.11.4.GIT