From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
The locking requirements here have changed slightly now that we can rely
on the ib_uverbs_file always existing and containing all the necessary
locking infrastructure.
That means we can get rid of the cleanup_mutex usage (this was protecting
the check on !uboj->context).
Otherwise, follow the same pattern that IDR uses for destroy, acquire
exclusive write access, then call destroy and the undo the 'lookup'.
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
---
drivers/infiniband/core/rdma_core.c | 41 ++++++++++++++++++++---------
1 file changed, 28 insertions(+), 13 deletions(-)
diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index 80e1e3cb211071..a55646cbf9b142 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -650,33 +650,48 @@ EXPORT_SYMBOL(uverbs_idr_class);
static void _uverbs_close_fd(struct ib_uobject *uobj)
{
- struct ib_uverbs_file *ufile = uobj->ufile;
int ret;
- mutex_lock(&ufile->cleanup_mutex);
+ /*
+ * uobject was already cleaned up, remove_commit_fd_uobject
+ * sets this
+ */
+ if (!uobj->context)
+ return;
- /* uobject was either already cleaned up or is cleaned up right now anyway */
- if (!uobj->context ||
- !down_read_trylock(&ufile->cleanup_rwsem))
- goto unlock;
+ /*
+ * lookup_get_fd_uobject holds the kref on the struct file any time a
+ * FD uobj is locked, which prevents this release method from being
+ * invoked. Meaning we can always get the write lock here, or we have
+ * a kernel bug. If so dangle the pointers and bail.
+ */
+ ret = uverbs_try_lock_object(uobj, true);
+ if (WARN(ret, "uverbs_close_fd() racing with lookup_get_fd_uobject()"))
+ return;
ret = _rdma_remove_commit_uobject(uobj, RDMA_REMOVE_CLOSE);
- up_read(&ufile->cleanup_rwsem);
if (ret)
- pr_warn("uverbs: unable to clean up uobject file in uverbs_close_fd.\n");
-unlock:
- mutex_unlock(&ufile->cleanup_mutex);
+ pr_warn("Unable to clean up uobject file in %s\n", __func__);
+
+ atomic_set(&uobj->usecnt, 0);
}
void uverbs_close_fd(struct file *f)
{
struct ib_uobject *uobj = f->private_data;
- struct kref *uverbs_file_ref = &uobj->ufile->ref;
+ struct ib_uverbs_file *ufile = uobj->ufile;
+
+ if (down_read_trylock(&ufile->cleanup_rwsem)) {
+ _uverbs_close_fd(uobj);
+ up_read(&ufile->cleanup_rwsem);
+ }
+
+ uobj->object = NULL;
+ /* Matches the get in alloc_begin_fd_uobject */
+ kref_put(&ufile->ref, ib_uverbs_release_file);
- _uverbs_close_fd(uobj);
/* Pairs with filp->private_data in alloc_begin_fd_uobject */
uverbs_uobject_put(uobj);
- kref_put(uverbs_file_ref, ib_uverbs_release_file);
}
static int __uverbs_cleanup_ufile(struct ib_uverbs_file *ufile,
--
2.18.0
--
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