From fd60ae404f104f12369e654af9cf03b1f1047661 Mon Sep 17 00:00:00 2001 From: Jack Morgenstein Date: Thu, 3 Aug 2006 10:56:42 -0700 Subject: [PATCH] IB/uverbs: Avoid a crash on device hot remove Wait until all users have closed their device context before allowing device unregistration to complete. This prevents a crash caused by referring to stale data structures. A better solution would be to have a way to revoke contexts rather than waiting for userspace to close the context, but that's a much bigger change that will have to wait. For now let's at least avoid the crash. Signed-off-by: Jack Morgenstein Signed-off-by: Michael S. Tsirkin Signed-off-by: Roland Dreier --- drivers/infiniband/core/uverbs.h | 2 ++ drivers/infiniband/core/uverbs_main.c | 8 +++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h index bb9bee56a824..102a59c033ff 100644 --- a/drivers/infiniband/core/uverbs.h +++ b/drivers/infiniband/core/uverbs.h @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -69,6 +70,7 @@ struct ib_uverbs_device { struct kref ref; + struct completion comp; int devnum; struct cdev *dev; struct class_device *class_dev; diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index e725cccc7cde..4e16314e8e6d 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -122,7 +122,7 @@ static void ib_uverbs_release_dev(struct kref *ref) struct ib_uverbs_device *dev = container_of(ref, struct ib_uverbs_device, ref); - kfree(dev); + complete(&dev->comp); } void ib_uverbs_release_ucq(struct ib_uverbs_file *file, @@ -740,6 +740,7 @@ static void ib_uverbs_add_one(struct ib_device *device) return; kref_init(&uverbs_dev->ref); + init_completion(&uverbs_dev->comp); spin_lock(&map_lock); uverbs_dev->devnum = find_first_zero_bit(dev_map, IB_UVERBS_MAX_DEVICES); @@ -793,6 +794,8 @@ err_cdev: err: kref_put(&uverbs_dev->ref, ib_uverbs_release_dev); + wait_for_completion(&uverbs_dev->comp); + kfree(uverbs_dev); return; } @@ -812,7 +815,10 @@ static void ib_uverbs_remove_one(struct ib_device *device) spin_unlock(&map_lock); clear_bit(uverbs_dev->devnum, dev_map); + kref_put(&uverbs_dev->ref, ib_uverbs_release_dev); + wait_for_completion(&uverbs_dev->comp); + kfree(uverbs_dev); } static int uverbs_event_get_sb(struct file_system_type *fs_type, int flags, -- 2.25.1