From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752587AbdLLQhE (ORCPT ); Tue, 12 Dec 2017 11:37:04 -0500 Received: from mailout2.w1.samsung.com ([210.118.77.12]:40528 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752464AbdLLQgR (ORCPT ); Tue, 12 Dec 2017 11:36:17 -0500 DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20171212163614euoutp0259e5db59f87d05fae89c62d27349b7f7~-mVFlVAjd3187731877euoutp02Y X-AuditID: cbfec7f1-f793a6d00000326b-6b-5a30057dc540 MIME-version: 1.0 Content-transfer-encoding: 8BIT Content-type: text/plain; charset="UTF-8" From: =?UTF-8?q?=C5=81ukasz=20Stelmach?= To: Krzysztof Kozlowski , robh+dt@kernel.org, Stephan Mueller , Herbert Xu , "David S . Miller" , Kukjin Kim , linux-crypto@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?=C5=81ukasz=20Stelmach?= , Marek Szyprowski , Bartlomiej Zolnierkiewicz Subject: [PATCH v3 4/4] crypto: exynos - Introduce mutex to prevent concurrent access to hardware Date: Tue, 12 Dec 2017 17:36:07 +0100 Message-id: <20171212163607.2985-5-l.stelmach@samsung.com> X-Mailer: git-send-email 2.11.0 In-reply-to: <20171212163607.2985-1-l.stelmach@samsung.com> In-reply-to: <20171211140623.7673-1-l.stelmach@samsung.com> Organization: Samsung R&D Institute Poland X-Brightmail-Tracker: H4sIAAAAAAAAA01SbUgTYRzvubvdzuHqmiv/mGSNLApMjT4cWqGSOOhLRF8yoy47lrhN2U2Z wUglVypMzV7WiF4ss1a2XDbSaOYcTQtcOiM1NF+qDxaVaVSglreb1Lff//97eZ7nx0PhijZJ DJWnN3IGPatVkTLC/fx3IMEsScpO+jK4iWmxOSXM5cApgqmeimVqJj/hTCDwQMoMeW8j5t3o b4wJtl8mGVvAgzHNvhEpU/HUJ2XOv2wm0iLV3wcGMHXrnSFM7X4Wr3Y5Kkm1tdWB1DOutXvJ bNmOY5w2r5gzJO46Ijve4xmWFNbGmJrffiZKkXNVFaIooLfDrRGsCkUswtXwatRJViEZpaAb EczbbJg4zCCobxwmRNV2aOgYChO3EMy6LpECIadXwq/6UUJIxek48PXnC2uc3gyPnjilon4W QW+wIqQn6XSoaeyWCISS9mAwWXceCQMupHa6e0KqKDoXnDcmcQETdDy872hAwglyOgWeuSXi jeKg3dIXwhF0Kswu3MeWcKX/dChmBb0F7pW/IYR8oGukMP+1jhTNu2GityX8tCiY8rdKRRwL wfrqJQOCrqs/w8Q5BDeup4k4FeYcYhBOL4ez7ou4WKoczlgUokQNdk952JoOt1vGCbEKK4KJ YBuqRevs/7Vn/9ee/b/2riHcgZRcEa/TcPy2rTyr44v0mq25BToXWvxQLxf804/R1+4UL6Ip pIqUj40lZiskbDFfovMioHCVUl5dvriSH2NLTnCGgsOGIi3He9EailBFy3dmWw4oaA1r5PI5 rpAzLLEYFRFTil5/8+xp6KeMmzONGVlmRWbO/s6cAoPWpDxYR3Y/LInKGFcevVh2c/hFwHWQ jzvke243+bs0dxP/sLoNlo/pB9aNWa9E77vQt/zHig+DnkLS1risoz0hQY9lmTWZvvUnp5tO ElfNSpN0Y1lnzrk5Y+2erMhfsU3JE9u076w+RZOK4I+zyVtwA8/+BcGKdptMAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprFIsWRmVeSWpSXmKPExsVy+t/xa7q1rAZRBqd7uCw2zljPajHnfAuL RfcrGYv+x6+ZLc6f38BucfPQCkaL+/d+Mllc3jWHzWLG+X1MFmuP3GW3aN17hN1i6um1LA48 Hp+uXGHy2LLyJpPHtgOqHptWdbJ59G1ZxejxeZNcAFsUl01Kak5mWWqRvl0CV8bJfbdYCyZI Vay9/YalgXG9aBcjJ4eEgInEov03mSBsMYkL99azdTFycQgJLGGU+LfiJBtIgldAUOLH5Hss XYwcHMwC8hJHLmWDhJkF1CUmzVvEDFH/jVHi+Y/VYPVsAo4S/UtPsIIkRAQOMEk09CwBm8os sIxR4k9PK1iVsECyxOzNe1hBbBYBVYkn+xcxgmzgFbCSOLCNFeIieYldbRfBbE4Ba4kv/9aB XSoEVPLnxF92mHjn8XY2mPj63+vA4vwCWhJrmq6zTGAUnoXkh1kIP8xC8sMCRuZVjCKppcW5 6bnFRnrFibnFpXnpesn5uZsYgTG27djPLTsYu94FH2IU4GBU4uF98EA/Sog1say4MvcQowQH s5IIb3cTUIg3JbGyKrUoP76oNCe1+BCjNAeLkjhv757VkUIC6YklqdmpqQWpRTBZJg5OqQbG 6Bu5R7vXP873njO7yPFpgdqZrNooyef+75yZ+yKDS7keFX/9c3PRsfssNlt3HK16Fmva3fwl /rLTirfm6pET9T2Usv8EpUreiG2cceysf5ei3555+1flefsd2ushJ7uUR66o5EQRo/OhnCVM Zu8uFLe9nCfx/arp2m6Nc0u7r+XVrWZb0fVPiaU4I9FQi7moOBEA0Lim860CAAA= X-CMS-MailID: 20171212163613eucas1p2f27c9c0924f94ad9a26b6870fcf5fe45 X-Msg-Generator: CA CMS-TYPE: 201P X-CMS-RootMailID: 20171212163613eucas1p2f27c9c0924f94ad9a26b6870fcf5fe45 X-RootMTR: 20171212163613eucas1p2f27c9c0924f94ad9a26b6870fcf5fe45 References: <20171212163607.2985-1-l.stelmach@samsung.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hardware operations like reading random numbers and setting a seed need to be conducted in a single thread. Therefore a mutex is required to prevent multiple threads (processes) from accessing the hardware at the same time. The sequence of mutex_lock() and mutex_unlock() in the exynos_rng_reseed() function enables switching between different threads waiting for the driver to generate random numbers for them. Signed-off-by: Łukasz Stelmach Reviewed-by: Krzysztof Kozlowski --- drivers/crypto/exynos-rng.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c index 825ed7bfd881..4a06092074b9 100644 --- a/drivers/crypto/exynos-rng.c +++ b/drivers/crypto/exynos-rng.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -79,6 +80,7 @@ struct exynos_rng_dev { enum exynos_prng_type type; void __iomem *mem; struct clk *clk; + struct mutex lock; /* Generated numbers stored for seeding during resume */ u8 seed_save[EXYNOS_RNG_SEED_SIZE]; unsigned int seed_save_len; @@ -191,6 +193,10 @@ static void exynos_rng_reseed(struct exynos_rng_dev *rng) return; exynos_rng_set_seed(rng, seed, read); + + /* Let others do some of their job. */ + mutex_unlock(&rng->lock); + mutex_lock(&rng->lock); } static int exynos_rng_generate(struct crypto_rng *tfm, @@ -206,6 +212,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, if (ret) return ret; + mutex_lock(&rng->lock); do { ret = exynos_rng_get_random(rng, dst, dlen, &read); if (ret) @@ -216,6 +223,7 @@ static int exynos_rng_generate(struct crypto_rng *tfm, exynos_rng_reseed(rng); } while (dlen > 0); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -233,7 +241,9 @@ static int exynos_rng_seed(struct crypto_rng *tfm, const u8 *seed, if (ret) return ret; + mutex_lock(&rng->lock); ret = exynos_rng_set_seed(ctx->rng, seed, slen); + mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); @@ -278,6 +288,8 @@ static int exynos_rng_probe(struct platform_device *pdev) rng->type = (enum exynos_prng_type)of_device_get_match_data(&pdev->dev); + mutex_init(&rng->lock); + rng->dev = &pdev->dev; rng->clk = devm_clk_get(&pdev->dev, "secss"); if (IS_ERR(rng->clk)) { @@ -328,9 +340,14 @@ static int __maybe_unused exynos_rng_suspend(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + /* Get new random numbers and store them for seeding on resume. */ exynos_rng_get_random(rng, rng->seed_save, sizeof(rng->seed_save), &(rng->seed_save_len)); + + mutex_unlock(&rng->lock); + dev_dbg(rng->dev, "Stored %u bytes for seeding on system resume\n", rng->seed_save_len); @@ -353,8 +370,12 @@ static int __maybe_unused exynos_rng_resume(struct device *dev) if (ret) return ret; + mutex_lock(&rng->lock); + ret = exynos_rng_set_seed(rng, rng->seed_save, rng->seed_save_len); + mutex_unlock(&rng->lock); + clk_disable_unprepare(rng->clk); return ret; -- 2.11.0