[PATCH v1 07/24] IB/uverbs: Add context import lock/unlock helper

Yuval Shaia
2019-08-21T14:22:51Z

From: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>

The lock/unlock helpers will be used in every import verb.

Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: Shamir Rabinovitch <srabinov7@gmail.com>
---
drivers/infiniband/core/uverbs.h | 2 +
drivers/infiniband/core/uverbs_cmd.c | 73 +++++++++++++++++++++++++++
drivers/infiniband/core/uverbs_main.c | 1 +
3 files changed, 76 insertions(+)

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 1e5aeb39f774..cf76336cb460 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -163,6 +163,8 @@ struct ib_uverbs_file {
struct page *disassociate_page;

struct xarray idr;
+
+ struct file *filp;
};

struct ib_uverbs_event {
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 4f42f9732dca..21f0a1a986f4 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -43,6 +43,7 @@

#include <rdma/uverbs_types.h>
#include <rdma/uverbs_std_types.h>
+#include <rdma/uverbs_ioctl.h>
#include "rdma_core.h"

#include "uverbs.h"
@@ -3791,6 +3792,78 @@ static void uverbs_init_attrs_ufile(struct uverbs_attr_bundle *attrs_bundle,
};
}

+/* ib_uverbs_import_lock - Function which gathers code that is
+ * common in the import verbs.
+ *
+ * This function guarntee that both source and destination files are
+ * protected from race with vfs close. The current file is protected
+ * from such race because verb is executed in a system-call context.
+ * The other file is protected by 'fget'. This function also ensures
+ * that ib_uobject identified by the type & handle is locked for read.
+ *
+ * Callers of this helper must also call ib_uverbs_import_unlock
+ * to undo any locking performed by this helper.
+ */
+static int ib_uverbs_import_lock(struct uverbs_attr_bundle *attrs,
+ int fd, u16 type, u32 handle,
+ struct ib_uobject **uobj,
+ struct file **filep,
+ struct ib_uverbs_file **ufile)
+{
+ struct ib_uverbs_file *file = attrs->ufile;
+ struct ib_uverbs_device *dev = file->device;
+ struct uverbs_attr_bundle fd_attrs;
+ struct ib_uverbs_device *fd_dev;
+ int ret = 0;
+
+ *filep = fget(fd);
+ if (!*filep)
+ return -EINVAL;
+
+ /* check uverbs ops exist */
+ if ((*filep)->f_op != file->filp->f_op) {
+ ret = -EINVAL;
+ goto file;
+ }
+
+ *ufile = (*filep)->private_data;
+ fd_dev = (*ufile)->device;
+
+ /* check that both files belong to same ib_device */
+ if (dev != fd_dev) {
+ ret = -EINVAL;
+ goto file;
+ }
+
+ uverbs_init_attrs_ufile(&fd_attrs, *ufile);
+
+ *uobj = uobj_get_read(type, handle, &fd_attrs);
+ if (IS_ERR(*uobj)) {
+ ret = -EINVAL;
+ goto file;
+ }
+
+ /* verify ib_object is shareable */
+ if (!(*uobj)->refcnt) {
+ ret = -EINVAL;
+ goto uobj;
+ }
+
+ return 0;
+uobj:
+ uobj_put_read(*uobj);
+file:
+ fput(*filep);
+ return ret;
+}
+
+static void ib_uverbs_import_unlock(struct ib_uobject *uobj,
+ struct file *filep)
+{
+ uobj_put_read(uobj);
+ fput(filep);
+}
+
/*
* Describe the input structs for write(). Some write methods have an input
* only struct, most have an input and output. If the struct has an output then
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 02b57240176c..e42a9b5c38b2 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -1095,6 +1095,7 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
mutex_init(&file->umap_lock);
INIT_LIST_HEAD(&file->umaps);

+ file->filp = filp;
filp->private_data = file;
list_add_tail(&file->list, &dev->uverbs_file_list);
mutex_unlock(&dev->lists_mutex);
--
2.20.1