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[2/4] hwrng: exynos - Add timeout for waiting on init done

Message ID 1445229462-32395-3-git-send-email-k.kozlowski@samsung.com (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show

Commit Message

Krzysztof Kozlowski Oct. 19, 2015, 4:37 a.m. UTC 
Driver may hang waiting indefinitely for PRNG to finish its
initialization stage. Instead of stalling return -ETIMEDOUT error.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
 drivers/char/hw_random/exynos-rng.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c
index dc4701fd814f..dfaaaafb8ddd 100644
--- a/drivers/char/hw_random/exynos-rng.c
+++ b/drivers/char/hw_random/exynos-rng.c
@@ -81,14 +81,17 @@  static int exynos_read(struct hwrng *rng, void *buf,
 	struct exynos_rng *exynos_rng = container_of(rng,
 						struct exynos_rng, rng);
 	u32 *data = buf;
+	int retry = 100;
 
 	pm_runtime_get_sync(exynos_rng->dev);
 
 	exynos_rng_writel(exynos_rng, PRNG_START, 0);
 
 	while (!(exynos_rng_readl(exynos_rng,
-			EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE))
+			EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
 		cpu_relax();
+	if (!retry)
+		return -ETIMEDOUT;
 
 	exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);