lkml.org 
[lkml]   [2019]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.19 034/191] OPP: Protect dev_list with opp_table lock
    Date
    From: Viresh Kumar <viresh.kumar@linaro.org>

    [ Upstream commit 3d2556992a878a2210d3be498416aee39e0c32aa ]

    The dev_list needs to be protected with a lock, else we may have
    simultaneous access (addition/removal) to it and that would be racy.
    Extend scope of the opp_table lock to protect dev_list as well.

    Tested-by: Niklas Cassel <niklas.cassel@linaro.org>
    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/opp/core.c | 21 +++++++++++++++++++--
    drivers/opp/cpu.c | 2 ++
    drivers/opp/opp.h | 2 +-
    3 files changed, 22 insertions(+), 3 deletions(-)

    diff --git a/drivers/opp/core.c b/drivers/opp/core.c
    index f3433bf47b100..14d4ef5943741 100644
    --- a/drivers/opp/core.c
    +++ b/drivers/opp/core.c
    @@ -48,9 +48,14 @@ static struct opp_device *_find_opp_dev(const struct device *dev,
    static struct opp_table *_find_opp_table_unlocked(struct device *dev)
    {
    struct opp_table *opp_table;
    + bool found;

    list_for_each_entry(opp_table, &opp_tables, node) {
    - if (_find_opp_dev(dev, opp_table)) {
    + mutex_lock(&opp_table->lock);
    + found = !!_find_opp_dev(dev, opp_table);
    + mutex_unlock(&opp_table->lock);
    +
    + if (found) {
    _get_opp_table_kref(opp_table);

    return opp_table;
    @@ -766,6 +771,8 @@ struct opp_device *_add_opp_dev(const struct device *dev,

    /* Initialize opp-dev */
    opp_dev->dev = dev;
    +
    + mutex_lock(&opp_table->lock);
    list_add(&opp_dev->node, &opp_table->dev_list);

    /* Create debugfs entries for the opp_table */
    @@ -773,6 +780,7 @@ struct opp_device *_add_opp_dev(const struct device *dev,
    if (ret)
    dev_err(dev, "%s: Failed to register opp debugfs (%d)\n",
    __func__, ret);
    + mutex_unlock(&opp_table->lock);

    return opp_dev;
    }
    @@ -791,6 +799,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev)
    if (!opp_table)
    return NULL;

    + mutex_init(&opp_table->lock);
    INIT_LIST_HEAD(&opp_table->dev_list);

    opp_dev = _add_opp_dev(dev, opp_table);
    @@ -812,7 +821,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev)

    BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);
    INIT_LIST_HEAD(&opp_table->opp_list);
    - mutex_init(&opp_table->lock);
    kref_init(&opp_table->kref);

    /* Secure the device table modification */
    @@ -854,6 +862,10 @@ static void _opp_table_kref_release(struct kref *kref)
    if (!IS_ERR(opp_table->clk))
    clk_put(opp_table->clk);

    + /*
    + * No need to take opp_table->lock here as we are guaranteed that no
    + * references to the OPP table are taken at this point.
    + */
    opp_dev = list_first_entry(&opp_table->dev_list, struct opp_device,
    node);

    @@ -1719,6 +1731,9 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev,
    {
    struct dev_pm_opp *opp, *tmp;

    + /* Protect dev_list */
    + mutex_lock(&opp_table->lock);
    +
    /* Find if opp_table manages a single device */
    if (list_is_singular(&opp_table->dev_list)) {
    /* Free static OPPs */
    @@ -1736,6 +1751,8 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev,
    } else {
    _remove_opp_dev(_find_opp_dev(dev, opp_table), opp_table);
    }
    +
    + mutex_unlock(&opp_table->lock);
    }

    void _dev_pm_opp_find_and_remove_table(struct device *dev, bool remove_all)
    diff --git a/drivers/opp/cpu.c b/drivers/opp/cpu.c
    index 0c09107094350..2868a022a0407 100644
    --- a/drivers/opp/cpu.c
    +++ b/drivers/opp/cpu.c
    @@ -222,8 +222,10 @@ int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
    cpumask_clear(cpumask);

    if (opp_table->shared_opp == OPP_TABLE_ACCESS_SHARED) {
    + mutex_lock(&opp_table->lock);
    list_for_each_entry(opp_dev, &opp_table->dev_list, node)
    cpumask_set_cpu(opp_dev->dev->id, cpumask);
    + mutex_unlock(&opp_table->lock);
    } else {
    cpumask_set_cpu(cpu_dev->id, cpumask);
    }
    diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
    index 7c540fd063b2d..e0866b1c1f1b2 100644
    --- a/drivers/opp/opp.h
    +++ b/drivers/opp/opp.h
    @@ -126,7 +126,7 @@ enum opp_table_access {
    * @dev_list: list of devices that share these OPPs
    * @opp_list: table of opps
    * @kref: for reference count of the table.
    - * @lock: mutex protecting the opp_list.
    + * @lock: mutex protecting the opp_list and dev_list.
    * @np: struct device_node pointer for opp's DT node.
    * @clock_latency_ns_max: Max clock latency in nanoseconds.
    * @shared_opp: OPP is shared between multiple devices.
    --
    2.20.1
    \
     
     \ /
      Last update: 2019-11-10 04:16    [W:4.040 / U:0.400 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site