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

[Lidong Chen]

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 <lidongc...@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