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    Subject[PATCH 5/9] driver/core: Convert to use built-in RCU list checking (v1)
    Date
    list_for_each_entry_rcu has built-in RCU and lock checking. Make use of
    it in driver core.

    Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
    ---
    drivers/base/base.h | 1 +
    drivers/base/core.c | 10 ++++++++++
    drivers/base/power/runtime.c | 15 ++++++++++-----
    3 files changed, 21 insertions(+), 5 deletions(-)

    diff --git a/drivers/base/base.h b/drivers/base/base.h
    index b405436ee28e..0d32544b6f91 100644
    --- a/drivers/base/base.h
    +++ b/drivers/base/base.h
    @@ -165,6 +165,7 @@ static inline int devtmpfs_init(void) { return 0; }
    /* Device links support */
    extern int device_links_read_lock(void);
    extern void device_links_read_unlock(int idx);
    +extern int device_links_read_lock_held(void);
    extern int device_links_check_suppliers(struct device *dev);
    extern void device_links_driver_bound(struct device *dev);
    extern void device_links_driver_cleanup(struct device *dev);
    diff --git a/drivers/base/core.c b/drivers/base/core.c
    index da84a73f2ba6..85e82f38717f 100644
    --- a/drivers/base/core.c
    +++ b/drivers/base/core.c
    @@ -68,6 +68,11 @@ void device_links_read_unlock(int idx)
    {
    srcu_read_unlock(&device_links_srcu, idx);
    }
    +
    +int device_links_read_lock_held(void)
    +{
    + return srcu_read_lock_held(&device_links_srcu);
    +}
    #else /* !CONFIG_SRCU */
    static DECLARE_RWSEM(device_links_lock);

    @@ -91,6 +96,11 @@ void device_links_read_unlock(int not_used)
    {
    up_read(&device_links_lock);
    }
    +
    +int device_links_read_lock_held(void)
    +{
    + return lock_is_held(&device_links_lock);
    +}
    #endif /* !CONFIG_SRCU */

    /**
    diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
    index 952a1e7057c7..7a10e8379a70 100644
    --- a/drivers/base/power/runtime.c
    +++ b/drivers/base/power/runtime.c
    @@ -287,7 +287,8 @@ static int rpm_get_suppliers(struct device *dev)
    {
    struct device_link *link;

    - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
    + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
    + device_links_read_lock_held()) {
    int retval;

    if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
    @@ -309,7 +310,8 @@ static void rpm_put_suppliers(struct device *dev)
    {
    struct device_link *link;

    - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
    + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
    + device_links_read_lock_held()) {
    if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
    continue;

    @@ -1640,7 +1642,8 @@ void pm_runtime_clean_up_links(struct device *dev)

    idx = device_links_read_lock();

    - list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
    + list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
    + device_links_read_lock_held()) {
    if (link->flags & DL_FLAG_STATELESS)
    continue;

    @@ -1662,7 +1665,8 @@ void pm_runtime_get_suppliers(struct device *dev)

    idx = device_links_read_lock();

    - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
    + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
    + device_links_read_lock_held())
    if (link->flags & DL_FLAG_PM_RUNTIME) {
    link->supplier_preactivated = true;
    refcount_inc(&link->rpm_active);
    @@ -1683,7 +1687,8 @@ void pm_runtime_put_suppliers(struct device *dev)

    idx = device_links_read_lock();

    - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
    + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
    + device_links_read_lock_held())
    if (link->supplier_preactivated) {
    link->supplier_preactivated = false;
    if (refcount_dec_not_one(&link->rpm_active))
    --
    2.22.0.510.g264f2c817a-goog
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