1 files changed, 92 insertions, 0 deletions

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 90d675ad9ec8..15937eb38aae 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -31,6 +31,7 @@
  */
 
 #include <linux/completion.h>
+#include <linux/file.h>
 #include <linux/mutex.h>
 #include <linux/poll.h>
 #include <linux/idr.h>
@@ -991,6 +992,96 @@ out:
         return ret;
 }
 
+static void ucma_lock_files(struct ucma_file *file1, struct ucma_file *file2)
+{
+        /* Acquire mutex's based on pointer comparison to prevent deadlock. */
+        if (file1 < file2) {
+                mutex_lock(&file1->mut);
+                mutex_lock(&file2->mut);
+        } else {
+                mutex_lock(&file2->mut);
+                mutex_lock(&file1->mut);
+        }
+}
+
+static void ucma_unlock_files(struct ucma_file *file1, struct ucma_file *file2)
+{
+        if (file1 < file2) {
+                mutex_unlock(&file2->mut);
+                mutex_unlock(&file1->mut);
+        } else {
+                mutex_unlock(&file1->mut);
+                mutex_unlock(&file2->mut);
+        }
+}
+
+static void ucma_move_events(struct ucma_context *ctx, struct ucma_file *file)
+{
+        struct ucma_event *uevent, *tmp;
+
+        list_for_each_entry_safe(uevent, tmp, &ctx->file->event_list, list)
+                if (uevent->ctx == ctx)
+                        list_move_tail(&uevent->list, &file->event_list);
+}
+
+static ssize_t ucma_migrate_id(struct ucma_file *new_file,
+                               const char __user *inbuf,
+                               int in_len, int out_len)
+{
+        struct rdma_ucm_migrate_id cmd;
+        struct rdma_ucm_migrate_resp resp;
+        struct ucma_context *ctx;
+        struct file *filp;
+        struct ucma_file *cur_file;
+        int ret = 0;
+
+        if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
+                return -EFAULT;
+
+        /* Get current fd to protect against it being closed */
+        filp = fget(cmd.fd);
+        if (!filp)
+                return -ENOENT;
+
+        /* Validate current fd and prevent destruction of id. */
+        ctx = ucma_get_ctx(filp->private_data, cmd.id);
+        if (IS_ERR(ctx)) {
+                ret = PTR_ERR(ctx);
+                goto file_put;
+        }
+
+        cur_file = ctx->file;
+        if (cur_file == new_file) {
+                resp.events_reported = ctx->events_reported;
+                goto response;
+        }
+
+        /*
+         * Migrate events between fd's, maintaining order, and avoiding new
+         * events being added before existing events.
+         */
+        ucma_lock_files(cur_file, new_file);
+        mutex_lock(&mut);
+
+        list_move_tail(&ctx->list, &new_file->ctx_list);
+        ucma_move_events(ctx, new_file);
+        ctx->file = new_file;
+        resp.events_reported = ctx->events_reported;
+
+        mutex_unlock(&mut);
+        ucma_unlock_files(cur_file, new_file);
+
+response:
+        if (copy_to_user((void __user *)(unsigned long)cmd.response,
+                         &resp, sizeof(resp)))
+                ret = -EFAULT;
+
+        ucma_put_ctx(ctx);
+file_put:
+        fput(filp);
+        return ret;
+}
+
 static ssize_t (*ucma_cmd_table[])(struct ucma_file *file,
                                    const char __user *inbuf,
                                    int in_len, int out_len) = {
@@ -1012,6 +1103,7 @@ static ssize_t (*ucma_cmd_table[])(struct ucma_file *file,
         [RDMA_USER_CM_CMD_NOTIFY]       = ucma_notify,
         [RDMA_USER_CM_CMD_JOIN_MCAST]   = ucma_join_multicast,
         [RDMA_USER_CM_CMD_LEAVE_MCAST]  = ucma_leave_multicast,
+        [RDMA_USER_CM_CMD_MIGRATE_ID]   = ucma_migrate_id
 };
 
 static ssize_t ucma_write(struct file *filp, const char __user *buf,