From: Leonard Crestez <leonard.crestez@nxp.com> To: Matthias Kaehlcke <mka@chromium.org>, MyungJoo Ham <myungjoo.ham@samsung.com>, Kyungmin Park <kyungmin.park@samsung.com> Cc: "Chanwoo Choi" <cw00.choi@samsung.com>, "Artur Świgoń" <a.swigon@partner.samsung.com>, "Krzysztof Kozlowski" <krzk@kernel.org>, "Georgi Djakov" <georgi.djakov@linaro.org>, "Lukasz Luba" <l.luba@partner.samsung.com>, "NXP Linux Team" <linux-imx@nxp.com>, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH] PM / devfreq: Lock devfreq in trans_stat_show Date: Mon, 23 Sep 2019 19:27:27 +0300 [thread overview] Message-ID: <714675448e7fbf3c930b0dca6fbe54fa5f87211b.1569256001.git.leonard.crestez@nxp.com> (raw) There is no locking in this sysfs show function so stats printing can race with a devfreq_update_status called as part of freq switching or with initialization. Also add an assert in devfreq_update_status to make it clear that lock must be held by caller. Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com> --- drivers/devfreq/devfreq.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) Changes since v1: * Split from series: low-priority bugfix not strictly required for PM QoS * Only keep lock during update, release before sprintf Link to v1: https://patchwork.kernel.org/patch/11149493/ diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 4c58fbf7d4e4..00fc23fea5b2 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -206,10 +206,11 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) { int lev, prev_lev, ret = 0; unsigned long cur_time; cur_time = jiffies; + lockdep_assert_held(&devfreq->lock); /* Immediately exit if previous_freq is not initialized yet. */ if (!devfreq->previous_freq) goto out; @@ -1507,16 +1508,22 @@ static ssize_t trans_stat_show(struct device *dev, struct devfreq *devfreq = to_devfreq(dev); ssize_t len; int i, j; unsigned int max_state = devfreq->profile->max_state; - if (!devfreq->stop_polling && - devfreq_update_status(devfreq, devfreq->previous_freq)) - return 0; if (max_state == 0) return sprintf(buf, "Not Supported.\n"); + /* lock and update */ + mutex_lock(&devfreq->lock); + if (!devfreq->stop_polling && + devfreq_update_status(devfreq, devfreq->previous_freq)) { + mutex_unlock(&devfreq->lock); + return 0; + } + mutex_unlock(&devfreq->lock); + len = sprintf(buf, " From : To\n"); len += sprintf(buf + len, " :"); for (i = 0; i < max_state; i++) len += sprintf(buf + len, "%10lu", devfreq->profile->freq_table[i]); -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: Leonard Crestez <leonard.crestez@nxp.com> To: Matthias Kaehlcke <mka@chromium.org>, MyungJoo Ham <myungjoo.ham@samsung.com>, Kyungmin Park <kyungmin.park@samsung.com> Cc: "Artur Świgoń" <a.swigon@partner.samsung.com>, linux-pm@vger.kernel.org, "Krzysztof Kozlowski" <krzk@kernel.org>, "Lukasz Luba" <l.luba@partner.samsung.com>, "Chanwoo Choi" <cw00.choi@samsung.com>, "NXP Linux Team" <linux-imx@nxp.com>, "Georgi Djakov" <georgi.djakov@linaro.org>, linux-arm-kernel@lists.infradead.org Subject: [PATCH] PM / devfreq: Lock devfreq in trans_stat_show Date: Mon, 23 Sep 2019 19:27:27 +0300 [thread overview] Message-ID: <714675448e7fbf3c930b0dca6fbe54fa5f87211b.1569256001.git.leonard.crestez@nxp.com> (raw) There is no locking in this sysfs show function so stats printing can race with a devfreq_update_status called as part of freq switching or with initialization. Also add an assert in devfreq_update_status to make it clear that lock must be held by caller. Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com> --- drivers/devfreq/devfreq.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) Changes since v1: * Split from series: low-priority bugfix not strictly required for PM QoS * Only keep lock during update, release before sprintf Link to v1: https://patchwork.kernel.org/patch/11149493/ diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 4c58fbf7d4e4..00fc23fea5b2 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -206,10 +206,11 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) { int lev, prev_lev, ret = 0; unsigned long cur_time; cur_time = jiffies; + lockdep_assert_held(&devfreq->lock); /* Immediately exit if previous_freq is not initialized yet. */ if (!devfreq->previous_freq) goto out; @@ -1507,16 +1508,22 @@ static ssize_t trans_stat_show(struct device *dev, struct devfreq *devfreq = to_devfreq(dev); ssize_t len; int i, j; unsigned int max_state = devfreq->profile->max_state; - if (!devfreq->stop_polling && - devfreq_update_status(devfreq, devfreq->previous_freq)) - return 0; if (max_state == 0) return sprintf(buf, "Not Supported.\n"); + /* lock and update */ + mutex_lock(&devfreq->lock); + if (!devfreq->stop_polling && + devfreq_update_status(devfreq, devfreq->previous_freq)) { + mutex_unlock(&devfreq->lock); + return 0; + } + mutex_unlock(&devfreq->lock); + len = sprintf(buf, " From : To\n"); len += sprintf(buf + len, " :"); for (i = 0; i < max_state; i++) len += sprintf(buf + len, "%10lu", devfreq->profile->freq_table[i]); -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-09-23 16:27 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <CGME20190923162736epcas3p2c1db3bf767a07f17b609bc91fbbd9648@epcas3p2.samsung.com> 2019-09-23 16:27 ` Leonard Crestez [this message] 2019-09-23 16:27 ` [PATCH] PM / devfreq: Lock devfreq in trans_stat_show Leonard Crestez 2019-09-23 18:54 ` Matthias Kaehlcke 2019-09-23 18:54 ` Matthias Kaehlcke 2019-09-23 23:34 ` Matthias Kaehlcke 2019-09-23 23:34 ` Matthias Kaehlcke 2019-09-24 2:11 ` Chanwoo Choi 2019-09-24 2:11 ` Chanwoo Choi 2019-09-24 7:44 ` Leonard Crestez 2019-09-24 7:44 ` Leonard Crestez 2019-09-24 15:44 ` Matthias Kaehlcke 2019-09-24 15:44 ` Matthias Kaehlcke 2019-09-25 1:21 ` Chanwoo Choi 2019-09-25 1:21 ` Chanwoo Choi 2019-09-25 19:36 ` Leonard Crestez 2019-09-25 19:36 ` Leonard Crestez
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