[PATCH v2 for-next 1/3] RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages

[Junxian Huang]

From: Chengchang Tang <tangchengchang@xxxxxxxxxx>

Provide a new api rdma_user_mmap_disassociate() for drivers to
disassociate mmap pages for ucontext.

Signed-off-by: Chengchang Tang <tangchengchang@xxxxxxxxxx>
Signed-off-by: Junxian Huang <huangjunxian6@xxxxxxxxxxxxx>
---
 drivers/infiniband/core/uverbs_main.c | 21 +++++++++++++++++++++
 include/rdma/ib_verbs.h               |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index bc099287de9a..00dab5bfb78c 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -880,6 +880,27 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
 	}
 }
 
+/**
+ * rdma_user_mmap_disassociate() - disassociate the mmap from the ucontext.
+ *
+ * @ucontext: associated user context.
+ *
+ * This function should be called by drivers that need to disable mmap for
+ * some ucontexts.
+ */
+void rdma_user_mmap_disassociate(struct ib_ucontext *ucontext)
+{
+	struct ib_uverbs_file *ufile = ucontext->ufile;
+
+	/* Racing with uverbs_destroy_ufile_hw */
+	if (!down_read_trylock(&ufile->hw_destroy_rwsem))
+		return;
+
+	uverbs_user_mmap_disassociate(ufile);
+	up_read(&ufile->hw_destroy_rwsem);
+}
+EXPORT_SYMBOL(rdma_user_mmap_disassociate);
+
 /*
  * ib_uverbs_open() does not need the BKL:
  *
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index a1dcf812d787..d6e34ca5c727 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2947,6 +2947,7 @@ int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
 				      struct rdma_user_mmap_entry *entry,
 				      size_t length, u32 min_pgoff,
 				      u32 max_pgoff);
+void rdma_user_mmap_disassociate(struct ib_ucontext *ucontext);
 
 static inline int
 rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
-- 
2.33.0