From 843e600b8a2b01463c4d873a90b2c2ea8033f1f6 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Thu, 16 Jul 2020 14:45:23 -0700 Subject: [PATCH] driver core: Fix sleeping in invalid context during device link deletion Marek and Guenter reported that commit 287905e68dd2 ("driver core: Expose device link details in sysfs") caused sleeping/scheduling while atomic warnings. BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 12, name: kworker/0:1 2 locks held by kworker/0:1/12: #0: ee8074a8 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x174/0x7dc #1: ee921f20 ((work_completion)(&sdp->work)){+.+.}-{0:0}, at: process_one_work+0x174/0x7dc Preemption disabled at: [] srcu_invoke_callbacks+0xc0/0x154 ----- 8< ----- SNIP [] (device_del) from [] (device_unregister+0x24/0x64) [] (device_unregister) from [] (srcu_invoke_callbacks+0xcc/0x154) [] (srcu_invoke_callbacks) from [] (process_one_work+0x234/0x7dc) [] (process_one_work) from [] (worker_thread+0x44/0x51c) [] (worker_thread) from [] (kthread+0x158/0x1a0) [] (kthread) from [] (ret_from_fork+0x14/0x20) Exception stack(0xee921fb0 to 0xee921ff8) This was caused by the device link device being released in the context of srcu_invoke_callbacks(). There is no need to wait till the RCU callback to release the device link device. So release the device earlier and move the call_srcu() into the device release code. That way, the memory will get freed only after the device is released AND the RCU callback is called. Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs") Reported-by: Marek Szyprowski Reported-by: Guenter Roeck Reported-by: Naresh Kamboju Signed-off-by: Saravana Kannan Tested-by: Marek Szyprowski Tested-by: Guenter Roeck Link: https://lore.kernel.org/r/20200716214523.2924704-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 45 +++++++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 18 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 294641040d48..b6e8b0bb76e4 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -307,10 +307,34 @@ static struct attribute *devlink_attrs[] = { }; ATTRIBUTE_GROUPS(devlink); +static void device_link_free(struct device_link *link) +{ + while (refcount_dec_not_one(&link->rpm_active)) + pm_runtime_put(link->supplier); + + put_device(link->consumer); + put_device(link->supplier); + 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) { - kfree(to_devlink(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)); +} +#endif static struct class devlink_class = { .name = "devlink", @@ -731,22 +755,7 @@ static void device_link_add_missing_supplier_links(void) mutex_unlock(&wfs_lock); } -static void device_link_free(struct device_link *link) -{ - while (refcount_dec_not_one(&link->rpm_active)) - pm_runtime_put(link->supplier); - - put_device(link->consumer); - put_device(link->supplier); - device_unregister(&link->link_dev); -} - #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 __device_link_del(struct kref *kref) { struct device_link *link = container_of(kref, struct device_link, kref); @@ -759,7 +768,7 @@ static void __device_link_del(struct kref *kref) list_del_rcu(&link->s_node); list_del_rcu(&link->c_node); - call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu); + device_unregister(&link->link_dev); } #else /* !CONFIG_SRCU */ static void __device_link_del(struct kref *kref) @@ -774,7 +783,7 @@ static void __device_link_del(struct kref *kref) list_del(&link->s_node); list_del(&link->c_node); - device_link_free(link); + device_unregister(&link->link_dev); } #endif /* !CONFIG_SRCU */ -- 2.20.1