RDMA/uverbs: Hoist the common process of disassociate_ucontext into ib core

This patch hoisted the common process of disassociate_ucontext
callback function into ib core code, and these code are common
to ervery ib_device driver.
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs_main.c

@@ -41,6 +41,8 @@
 #include <linux/fs.h>
 #include <linux/poll.h>
 #include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/task.h>
 #include <linux/file.h>
 #include <linux/cdev.h>
 #include <linux/anon_inodes.h>
@@ -1090,6 +1092,44 @@ static void ib_uverbs_add_one(struct ib_device *device)
 	return;
 }
 
+static void ib_uverbs_disassociate_ucontext(struct ib_ucontext *ibcontext)
+{
+	struct ib_device *ib_dev = ibcontext->device;
+	struct task_struct *owning_process  = NULL;
+	struct mm_struct   *owning_mm       = NULL;
+
+	owning_process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
+	if (!owning_process)
+		return;
+
+	owning_mm = get_task_mm(owning_process);
+	if (!owning_mm) {
+		pr_info("no mm, disassociate ucontext is pending task termination\n");
+		while (1) {
+			put_task_struct(owning_process);
+			usleep_range(1000, 2000);
+			owning_process = get_pid_task(ibcontext->tgid,
+						      PIDTYPE_PID);
+			if (!owning_process ||
+			    owning_process->state == TASK_DEAD) {
+				pr_info("disassociate ucontext done, task was terminated\n");
+				/* in case task was dead need to release the
+				 * task struct.
+				 */
+				if (owning_process)
+					put_task_struct(owning_process);
+				return;
+			}
+		}
+	}
+
+	down_write(&owning_mm->mmap_sem);
+	ib_dev->disassociate_ucontext(ibcontext);
+	up_write(&owning_mm->mmap_sem);
+	mmput(owning_mm);
+	put_task_struct(owning_process);
+}
+
 static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev,
 					struct ib_device *ib_dev)
 {
@@ -1130,7 +1170,7 @@ static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev,
 			 * (e.g mmput).
 			 */
 			ib_uverbs_event_handler(&file->event_handler, &event);
-			ib_dev->disassociate_ucontext(ucontext);
+			ib_uverbs_disassociate_ucontext(ucontext);
 			mutex_lock(&file->cleanup_mutex);
 			ib_uverbs_cleanup_ucontext(file, ucontext, true);
 			mutex_unlock(&file->cleanup_mutex);

drivers/infiniband/hw/mlx4/main.c

@@ -1189,40 +1189,10 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	int ret = 0;
 	struct vm_area_struct *vma;
 	struct mlx4_ib_ucontext *context = to_mucontext(ibcontext);
-	struct task_struct *owning_process  = NULL;
-	struct mm_struct   *owning_mm       = NULL;
-
-	owning_process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
-	if (!owning_process)
-		return;
-
-	owning_mm = get_task_mm(owning_process);
-	if (!owning_mm) {
-		pr_info("no mm, disassociate ucontext is pending task termination\n");
-		while (1) {
-			/* make sure that task is dead before returning, it may
-			 * prevent a rare case of module down in parallel to a
-			 * call to mlx4_ib_vma_close.
-			 */
-			put_task_struct(owning_process);
-			usleep_range(1000, 2000);
-			owning_process = get_pid_task(ibcontext->tgid,
-						      PIDTYPE_PID);
-			if (!owning_process ||
-			    owning_process->state == TASK_DEAD) {
-				pr_info("disassociate ucontext done, task was terminated\n");
-				/* in case task was dead need to release the task struct */
-				if (owning_process)
-					put_task_struct(owning_process);
-				return;
-			}
-		}
-	}
 
 	/* need to protect from a race on closing the vma as part of
 	 * mlx4_ib_vma_close().
 	 */
-	down_write(&owning_mm->mmap_sem);
 	for (i = 0; i < HW_BAR_COUNT; i++) {
 		vma = context->hw_bar_info[i].vma;
 		if (!vma)
@@ -1241,10 +1211,6 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		/* context going to be destroyed, should not access ops any more */
 		context->hw_bar_info[i].vma->vm_ops = NULL;
 	}
-
-	up_write(&owning_mm->mmap_sem);
-	mmput(owning_mm);
-	put_task_struct(owning_process);
 }
 
 static void mlx4_ib_set_vma_data(struct vm_area_struct *vma,

drivers/infiniband/hw/mlx5/main.c

@@ -1973,38 +1973,7 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	struct vm_area_struct *vma;
 	struct mlx5_ib_vma_private_data *vma_private, *n;
 	struct mlx5_ib_ucontext *context = to_mucontext(ibcontext);
-	struct task_struct *owning_process  = NULL;
-	struct mm_struct   *owning_mm       = NULL;
 
-	owning_process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
-	if (!owning_process)
-		return;
-
-	owning_mm = get_task_mm(owning_process);
-	if (!owning_mm) {
-		pr_info("no mm, disassociate ucontext is pending task termination\n");
-		while (1) {
-			put_task_struct(owning_process);
-			usleep_range(1000, 2000);
-			owning_process = get_pid_task(ibcontext->tgid,
-						      PIDTYPE_PID);
-			if (!owning_process ||
-			    owning_process->state == TASK_DEAD) {
-				pr_info("disassociate ucontext done, task was terminated\n");
-				/* in case task was dead need to release the
-				 * task struct.
-				 */
-				if (owning_process)
-					put_task_struct(owning_process);
-				return;
-			}
-		}
-	}
-
-	/* need to protect from a race on closing the vma as part of
-	 * mlx5_ib_vma_close.
-	 */
-	down_write(&owning_mm->mmap_sem);
 	mutex_lock(&context->vma_private_list_mutex);
 	list_for_each_entry_safe(vma_private, n, &context->vma_private_list,
 				 list) {
@@ -2021,9 +1990,6 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		kfree(vma_private);
 	}
 	mutex_unlock(&context->vma_private_list_mutex);
-	up_write(&owning_mm->mmap_sem);
-	mmput(owning_mm);
-	put_task_struct(owning_process);
 }
 
 static inline char *mmap_cmd2str(enum mlx5_ib_mmap_cmd cmd)