[PATCH] IB/umem: use tgid instead of pid in ib_umem structure

[Lidong Chen <jemmy858585@gmail.com>]

The userspace may invoke ibv_reg_mr and ibv_dereg_mr by different threads.
If when ibv_dereg_mr invoke and the thread which invoked ibv_reg_mr has
exited, get_pid_task will return NULL, ib_umem_release does not decrease
mm->pinned_vm. This patch fixes it by use tgid.

Signed-off-by: Lidong Chen <lidongchen@tencent.com>
---
 drivers/infiniband/core/umem.c | 12 ++++++------
 include/rdma/ib_umem.h         |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 9a4e899..8813ba5 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -119,7 +119,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	umem->length     = size;
 	umem->address    = addr;
 	umem->page_shift = PAGE_SHIFT;
-	umem->pid	 = get_task_pid(current, PIDTYPE_PID);
+	umem->tgid	 = get_task_pid(current->group_leader, PIDTYPE_PID);
 	/*
 	 * We ask for writable memory if any of the following
 	 * access flags are set.  "Local write" and "remote write"
@@ -132,7 +132,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 		 IB_ACCESS_REMOTE_ATOMIC | IB_ACCESS_MW_BIND));
 
 	if (access & IB_ACCESS_ON_DEMAND) {
-		put_pid(umem->pid);
+		put_pid(umem->tgid);
 		ret = ib_umem_odp_get(context, umem, access);
 		if (ret) {
 			kfree(umem);
@@ -148,7 +148,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 
 	page_list = (struct page **) __get_free_page(GFP_KERNEL);
 	if (!page_list) {
-		put_pid(umem->pid);
+		put_pid(umem->tgid);
 		kfree(umem);
 		return ERR_PTR(-ENOMEM);
 	}
@@ -231,7 +231,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	if (ret < 0) {
 		if (need_release)
 			__ib_umem_release(context->device, umem, 0);
-		put_pid(umem->pid);
+		put_pid(umem->tgid);
 		kfree(umem);
 	} else
 		current->mm->pinned_vm = locked;
@@ -274,8 +274,8 @@ void ib_umem_release(struct ib_umem *umem)
 
 	__ib_umem_release(umem->context->device, umem, 1);
 
-	task = get_pid_task(umem->pid, PIDTYPE_PID);
-	put_pid(umem->pid);
+	task = get_pid_task(umem->tgid, PIDTYPE_PID);
+	put_pid(umem->tgid);
 	if (!task)
 		goto out;
 	mm = get_task_mm(task);
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 23159dd..2398849 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -48,7 +48,7 @@ struct ib_umem {
 	int                     writable;
 	int                     hugetlb;
 	struct work_struct	work;
-	struct pid             *pid;
+	struct pid             *tgid;
 	struct mm_struct       *mm;
 	unsigned long		diff;
 	struct ib_umem_odp     *odp_data;
-- 
1.8.3.1