Messages in this thread | | | Date | Sat, 18 Jun 2022 22:57:59 +0900 | Subject | Re: [PATCH v4 3/4] PM / devfreq: Rework freq_table to be local to devfreq struct | From | Chanwoo Choi <> |
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On 22. 6. 18. 04:38, Christian Marangi wrote: > On Sat, Jun 18, 2022 at 04:33:19AM +0900, Chanwoo Choi wrote: >> Hi, >> >> Thanks for the good catch. >> >> >> I think that this patch fixes issue of commit 0ec09ac2cebe >> ("PM / devfreq: Set the freq_table of devfreq device"). >> > > Should I add this to the Fixes list?
Replace fixes commit information with commit 0ec09ac2cebe. I'd like you to make the patch separated from this series and then send them to linux-stable mailling list tool because I think this patch should be maintained by linux stable patches.
> >> When some devfreq driver without using passive governor >> faces on the all errors including PROBE_DEFER >> after executing devfreq_add_device, this issue will happen. >> >> Also need to check the devfreq device driver using freq_table >> which was allocated dynamically. In case of devfreq/drivers/exynos-bus.c >> used the devfreq->profile->freq_table after devfreq_add_device. >> >> On 22. 6. 15. 08:09, Christian 'Ansuel' Marangi wrote: >>> Currently we reference the freq_table to the profile defined one and we >>> make changes on it. Devfreq never supported PROBE_DEFER before the cpu >>> based scaling support to the passive governor and assumed that a devfreq >>> device could only had error and be done with it. >>> Now that a device can PROBE_DEFER a rework to the freq_table logic is >>> required. >>> >>> If a device PROBE_DEFER on the GOV_START, the freq_table is already set >>> in the device profile struct and its init is skipped. This is due to the >>> fact that it's common for devs to declare this kind of struct static. >>> This cause the devfreq logic to find a freq table declared (freq_table >>> not NULL) with random data and poiting to the old addrs freed by devm. >> > This problem CAN be solved by devs by clearing the freq_table in their >>> profile struct on driver exit path but it should not be trusted and it >>> looks to use a flawed logic. >>> >>> A better solution is to move the freq_table and max_state to the >>> devfreq struct and never change the profile struct. >>> This permit to correctly handle PROBE_DEFER since the devfreq struct is >>> reallocated and contains new values. >>> Also the profile struct should only be used to init the driver and should >>> not be used by the devfreq to write the freq_table if it's not provided >>> by the driver. >>> >> >> If possible, could you explain the patch description more simply? >> Maybe, just focus on the 'freq_table' issue by device managed functions (devs). >> > > Sure!
Thanks.
> >> >>> Fixes: a03dacb0316f ("PM / devfreq: Add cpu based scaling support to passive governor") >>> Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com> >>> --- >>> drivers/devfreq/devfreq.c | 71 ++++++++++++++---------------- >>> drivers/devfreq/governor_passive.c | 14 +++--- >>> include/linux/devfreq.h | 4 ++ >>> 3 files changed, 45 insertions(+), 44 deletions(-) >>> >>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >>> index 01474daf4548..2e2b3b414d67 100644 >>> --- a/drivers/devfreq/devfreq.c >>> +++ b/drivers/devfreq/devfreq.c >>> @@ -123,7 +123,7 @@ void devfreq_get_freq_range(struct devfreq *devfreq, >>> unsigned long *min_freq, >>> unsigned long *max_freq) >>> { >>> - unsigned long *freq_table = devfreq->profile->freq_table; >>> + unsigned long *freq_table = devfreq->freq_table; >>> s32 qos_min_freq, qos_max_freq; >>> >>> lockdep_assert_held(&devfreq->lock); >>> @@ -133,11 +133,11 @@ void devfreq_get_freq_range(struct devfreq *devfreq, >>> * The devfreq drivers can initialize this in either ascending or >>> * descending order and devfreq core supports both. >>> */ >>> - if (freq_table[0] < freq_table[devfreq->profile->max_state - 1]) { >>> + if (freq_table[0] < freq_table[devfreq->max_state - 1]) { >>> *min_freq = freq_table[0]; >>> - *max_freq = freq_table[devfreq->profile->max_state - 1]; >>> + *max_freq = freq_table[devfreq->max_state - 1]; >>> } else { >>> - *min_freq = freq_table[devfreq->profile->max_state - 1]; >>> + *min_freq = freq_table[devfreq->max_state - 1]; >>> *max_freq = freq_table[0]; >>> } >>> >>> @@ -169,8 +169,8 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq) >>> { >>> int lev; >>> >>> - for (lev = 0; lev < devfreq->profile->max_state; lev++) >>> - if (freq == devfreq->profile->freq_table[lev]) >>> + for (lev = 0; lev < devfreq->max_state; lev++) >>> + if (freq == devfreq->freq_table[lev]) >>> return lev; >>> >>> return -EINVAL; >>> @@ -178,7 +178,6 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq) >>> >>> static int set_freq_table(struct devfreq *devfreq) >>> { >>> - struct devfreq_dev_profile *profile = devfreq->profile; >>> struct dev_pm_opp *opp; >>> unsigned long freq; >>> int i, count; >>> @@ -188,25 +187,22 @@ static int set_freq_table(struct devfreq *devfreq) >>> if (count <= 0) >>> return -EINVAL; >>> >>> - profile->max_state = count; >>> - profile->freq_table = devm_kcalloc(devfreq->dev.parent, >>> - profile->max_state, >>> - sizeof(*profile->freq_table), >>> - GFP_KERNEL); >>> - if (!profile->freq_table) { >>> - profile->max_state = 0; >>> + devfreq->max_state = count; >>> + devfreq->freq_table = devm_kcalloc(devfreq->dev.parent, >>> + devfreq->max_state, >>> + sizeof(*devfreq->freq_table), >>> + GFP_KERNEL); >>> + if (!devfreq->freq_table) >>> return -ENOMEM; >>> - } >>> >>> - for (i = 0, freq = 0; i < profile->max_state; i++, freq++) { >>> + for (i = 0, freq = 0; i < devfreq->max_state; i++, freq++) { >>> opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq); >>> if (IS_ERR(opp)) { >>> - devm_kfree(devfreq->dev.parent, profile->freq_table); >>> - profile->max_state = 0; >>> + devm_kfree(devfreq->dev.parent, devfreq->freq_table); >>> return PTR_ERR(opp); >>> } >>> dev_pm_opp_put(opp); >>> - profile->freq_table[i] = freq; >>> + devfreq->freq_table[i] = freq; >>> } >>> >>> return 0; >>> @@ -246,7 +242,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) >>> >>> if (lev != prev_lev) { >>> devfreq->stats.trans_table[ >>> - (prev_lev * devfreq->profile->max_state) + lev]++; >>> + (prev_lev * devfreq->max_state) + lev]++; >>> devfreq->stats.total_trans++; >>> } >>> >>> @@ -835,6 +831,9 @@ struct devfreq *devfreq_add_device(struct device *dev, >>> if (err < 0) >>> goto err_dev; >>> mutex_lock(&devfreq->lock); >>> + } else { >>> + devfreq->freq_table = devfreq->profile->freq_table; >>> + devfreq->max_state = devfreq->profile->max_state; >>> } >>> >>> devfreq->scaling_min_freq = find_available_min_freq(devfreq); >>> @@ -870,8 +869,8 @@ struct devfreq *devfreq_add_device(struct device *dev, >>> >>> devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev, >>> array3_size(sizeof(unsigned int), >>> - devfreq->profile->max_state, >>> - devfreq->profile->max_state), >>> + devfreq->max_state, >>> + devfreq->max_state), >>> GFP_KERNEL); >>> if (!devfreq->stats.trans_table) { >>> mutex_unlock(&devfreq->lock); >>> @@ -880,7 +879,7 @@ struct devfreq *devfreq_add_device(struct device *dev, >>> } >>> >>> devfreq->stats.time_in_state = devm_kcalloc(&devfreq->dev, >>> - devfreq->profile->max_state, >>> + devfreq->max_state, >>> sizeof(*devfreq->stats.time_in_state), >>> GFP_KERNEL); >>> if (!devfreq->stats.time_in_state) { >>> @@ -1665,9 +1664,9 @@ static ssize_t available_frequencies_show(struct device *d, >>> >>> mutex_lock(&df->lock); >>> >>> - for (i = 0; i < df->profile->max_state; i++) >>> + for (i = 0; i < df->max_state; i++) >>> count += scnprintf(&buf[count], (PAGE_SIZE - count - 2), >>> - "%lu ", df->profile->freq_table[i]); >>> + "%lu ", df->freq_table[i]); >>> >>> mutex_unlock(&df->lock); >>> /* Truncate the trailing space */ >>> @@ -1690,7 +1689,7 @@ static ssize_t trans_stat_show(struct device *dev, >>> >>> if (!df->profile) >>> return -EINVAL; >>> - max_state = df->profile->max_state; >>> + max_state = df->max_state; >>> >>> if (max_state == 0) >>> return sprintf(buf, "Not Supported.\n"); >>> @@ -1707,19 +1706,17 @@ static ssize_t trans_stat_show(struct device *dev, >>> len += sprintf(buf + len, " :"); >>> for (i = 0; i < max_state; i++) >>> len += sprintf(buf + len, "%10lu", >>> - df->profile->freq_table[i]); >>> + df->freq_table[i]); >>> >>> len += sprintf(buf + len, " time(ms)\n"); >>> >>> for (i = 0; i < max_state; i++) { >>> - if (df->profile->freq_table[i] >>> - == df->previous_freq) { >>> + if (df->freq_table[i] == df->previous_freq) >>> len += sprintf(buf + len, "*"); >>> - } else { >>> + else >>> len += sprintf(buf + len, " "); >>> - } >>> - len += sprintf(buf + len, "%10lu:", >>> - df->profile->freq_table[i]); >>> + >>> + len += sprintf(buf + len, "%10lu:", df->freq_table[i]); >>> for (j = 0; j < max_state; j++) >>> len += sprintf(buf + len, "%10u", >>> df->stats.trans_table[(i * max_state) + j]); >>> @@ -1743,7 +1740,7 @@ static ssize_t trans_stat_store(struct device *dev, >>> if (!df->profile) >>> return -EINVAL; >>> >>> - if (df->profile->max_state == 0) >>> + if (df->max_state == 0) >>> return count; >>> >>> err = kstrtoint(buf, 10, &value); >>> @@ -1751,11 +1748,11 @@ static ssize_t trans_stat_store(struct device *dev, >>> return -EINVAL; >>> >>> mutex_lock(&df->lock); >>> - memset(df->stats.time_in_state, 0, (df->profile->max_state * >>> + memset(df->stats.time_in_state, 0, (df->max_state * >>> sizeof(*df->stats.time_in_state))); >>> memset(df->stats.trans_table, 0, array3_size(sizeof(unsigned int), >>> - df->profile->max_state, >>> - df->profile->max_state)); >>> + df->max_state, >>> + df->max_state)); >>> df->stats.total_trans = 0; >>> df->stats.last_update = get_jiffies_64(); >>> mutex_unlock(&df->lock); >>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c >>> index dcc9dd518197..1810966fd61d 100644 >>> --- a/drivers/devfreq/governor_passive.c >>> +++ b/drivers/devfreq/governor_passive.c >>> @@ -145,18 +145,18 @@ static int get_target_freq_with_devfreq(struct devfreq *devfreq, >>> goto out; >>> >>> /* Use interpolation if required opps is not available */ >>> - for (i = 0; i < parent_devfreq->profile->max_state; i++) >>> - if (parent_devfreq->profile->freq_table[i] == *freq) >>> + for (i = 0; i < parent_devfreq->max_state; i++) >>> + if (parent_devfreq->freq_table[i] == *freq) >>> break; >>> >>> - if (i == parent_devfreq->profile->max_state) >>> + if (i == parent_devfreq->max_state) >>> return -EINVAL; >>> >>> - if (i < devfreq->profile->max_state) { >>> - child_freq = devfreq->profile->freq_table[i]; >>> + if (i < devfreq->max_state) { >>> + child_freq = devfreq->freq_table[i]; >>> } else { >>> - count = devfreq->profile->max_state; >>> - child_freq = devfreq->profile->freq_table[count - 1]; >>> + count = devfreq->max_state; >>> + child_freq = devfreq->freq_table[count - 1]; >>> } >>> >>> out: >>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h >>> index dc10bee75a72..770a7532655c 100644 >>> --- a/include/linux/devfreq.h >>> +++ b/include/linux/devfreq.h >>> @@ -185,6 +185,10 @@ struct devfreq { >>> struct notifier_block nb; >>> struct delayed_work work; >>> >>> + /* devfreq local freq_table */
This comment is not necessary. Please remove it.
>>> + unsigned long *freq_table; >>> + unsigned int max_state;
And need to add the description of newly added variables to 'struct devfreq' structure description.
>>> + >>> unsigned long previous_freq; >>> struct devfreq_dev_status last_status; >>> >> >> >> -- >> Best Regards, >> Samsung Electronics >> Chanwoo Choi >
-- Best Regards, Samsung Electronics Chanwoo Choi
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