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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2021-05-14 14:10:15 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-05-21 22:12:09 +0200
commit80dd33cf72d1ab4f0af303f1fa242c6d6c8d328f (patch)
tree5fb932417cb7394215d515f39e19ee558c44d52e /drivers/base
parent5881fa8dc2de9697a89451f6518e8b3a796c09c6 (diff)
drivers: base: Fix device link removal
When device_link_free() drops references to the supplier and consumer devices of the device link going away and the reference being dropped turns out to be the last one for any of those device objects, its ->release callback will be invoked and it may sleep which goes against the SRCU callback execution requirements. To address this issue, make the device link removal code carry out the device_link_free() actions preceded by SRCU synchronization from a separate work item (the "long" workqueue is used for that, because it does not matter when the device link memory is released and it may take time to get to that point) instead of using SRCU callbacks. While at it, make the code work analogously when SRCU is not enabled to reduce the differences between the SRCU and non-SRCU cases. Fixes: 843e600b8a2b ("driver core: Fix sleeping in invalid context during device link deletion") Cc: stable <stable@vger.kernel.org> Reported-by: chenxiang (M) <chenxiang66@hisilicon.com> Tested-by: chenxiang (M) <chenxiang66@hisilicon.com> Reviewed-by: Saravana Kannan <saravanak@google.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/5722787.lOV4Wx5bFT@kreacher Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/core.c37
1 files changed, 23 insertions, 14 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 628e33939aca..61c19641e1d0 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -194,6 +194,11 @@ int device_links_read_lock_held(void)
{
return srcu_read_lock_held(&device_links_srcu);
}
+
+static void device_link_synchronize_removal(void)
+{
+ synchronize_srcu(&device_links_srcu);
+}
#else /* !CONFIG_SRCU */
static DECLARE_RWSEM(device_links_lock);
@@ -224,6 +229,10 @@ int device_links_read_lock_held(void)
return lockdep_is_held(&device_links_lock);
}
#endif
+
+static inline void device_link_synchronize_removal(void)
+{
+}
#endif /* !CONFIG_SRCU */
static bool device_is_ancestor(struct device *dev, struct device *target)
@@ -445,8 +454,13 @@ static struct attribute *devlink_attrs[] = {
};
ATTRIBUTE_GROUPS(devlink);
-static void device_link_free(struct device_link *link)
+static void device_link_release_fn(struct work_struct *work)
{
+ struct device_link *link = container_of(work, struct device_link, rm_work);
+
+ /* Ensure that all references to the link object have been dropped. */
+ device_link_synchronize_removal();
+
while (refcount_dec_not_one(&link->rpm_active))
pm_runtime_put(link->supplier);
@@ -455,24 +469,19 @@ static void device_link_free(struct device_link *link)
kfree(link);
}
-#ifdef CONFIG_SRCU
-static void __device_link_free_srcu(struct rcu_head *rhead)
-{
- device_link_free(container_of(rhead, struct device_link, rcu_head));
-}
-
static void devlink_dev_release(struct device *dev)
{
struct device_link *link = to_devlink(dev);
- call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);
-}
-#else
-static void devlink_dev_release(struct device *dev)
-{
- device_link_free(to_devlink(dev));
+ INIT_WORK(&link->rm_work, device_link_release_fn);
+ /*
+ * It may take a while to complete this work because of the SRCU
+ * synchronization in device_link_release_fn() and if the consumer or
+ * supplier devices get deleted when it runs, so put it into the "long"
+ * workqueue.
+ */
+ queue_work(system_long_wq, &link->rm_work);
}
-#endif
static struct class devlink_class = {
.name = "devlink",