RDMA/usnic: Do not use ucontext->tgid

Update this driver to match the code it copies from umem.c which no longer
uses tgid.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/usnic/usnic_uiom.c

@@ -54,18 +54,6 @@ static struct workqueue_struct *usnic_uiom_wq;
 	((void *) &((struct usnic_uiom_chunk *) 0)->page_list[1] -	\
 	(void *) &((struct usnic_uiom_chunk *) 0)->page_list[0]))
 
-static void usnic_uiom_reg_account(struct work_struct *work)
-{
-	struct usnic_uiom_reg *umem = container_of(work,
-						struct usnic_uiom_reg, work);
-
-	down_write(&umem->mm->mmap_sem);
-	umem->mm->locked_vm -= umem->diff;
-	up_write(&umem->mm->mmap_sem);
-	mmput(umem->mm);
-	kfree(umem);
-}
-
 static int usnic_uiom_dma_fault(struct iommu_domain *domain,
 				struct device *dev,
 				unsigned long iova, int flags,
@@ -99,8 +87,9 @@ static void usnic_uiom_put_pages(struct list_head *chunk_list, int dirty)
 }
 
 static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
-				int dmasync, struct list_head *chunk_list)
+				int dmasync, struct usnic_uiom_reg *uiomr)
 {
+	struct list_head *chunk_list = &uiomr->chunk_list;
 	struct page **page_list;
 	struct scatterlist *sg;
 	struct usnic_uiom_chunk *chunk;
@@ -114,6 +103,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 	int flags;
 	dma_addr_t pa;
 	unsigned int gup_flags;
+	struct mm_struct *mm;
 
 	/*
 	 * If the combination of the addr and size requested for this memory
@@ -136,7 +126,8 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 
 	npages = PAGE_ALIGN(size + (addr & ~PAGE_MASK)) >> PAGE_SHIFT;
 
-	down_write(&current->mm->mmap_sem);
+	uiomr->owning_mm = mm = current->mm;
+	down_write(&mm->mmap_sem);
 
 	locked = npages + current->mm->pinned_vm;
 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
@@ -196,10 +187,12 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 out:
 	if (ret < 0)
 		usnic_uiom_put_pages(chunk_list, 0);
-	else
-		current->mm->pinned_vm = locked;
+	else {
+		mm->pinned_vm = locked;
+		mmgrab(uiomr->owning_mm);
+	}
 
-	up_write(&current->mm->mmap_sem);
+	up_write(&mm->mmap_sem);
 	free_page((unsigned long) page_list);
 	return ret;
 }
@@ -379,7 +372,7 @@ struct usnic_uiom_reg *usnic_uiom_reg_get(struct usnic_uiom_pd *pd,
 	uiomr->pd = pd;
 
 	err = usnic_uiom_get_pages(addr, size, writable, dmasync,
-					&uiomr->chunk_list);
+				   uiomr);
 	if (err) {
 		usnic_err("Failed get_pages vpn [0x%lx,0x%lx] err %d\n",
 				vpn_start, vpn_last, err);
@@ -426,29 +419,39 @@ struct usnic_uiom_reg *usnic_uiom_reg_get(struct usnic_uiom_pd *pd,
 out_put_pages:
 	usnic_uiom_put_pages(&uiomr->chunk_list, 0);
 	spin_unlock(&pd->lock);
+	mmdrop(uiomr->owning_mm);
 out_free_uiomr:
 	kfree(uiomr);
 	return ERR_PTR(err);
 }
 
-void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr,
-			    struct ib_ucontext *ucontext)
+static void __usnic_uiom_release_tail(struct usnic_uiom_reg *uiomr)
 {
-	struct task_struct *task;
-	struct mm_struct *mm;
-	unsigned long diff;
+	mmdrop(uiomr->owning_mm);
+	kfree(uiomr);
+}
 
-	__usnic_uiom_reg_release(uiomr->pd, uiomr, 1);
+static inline size_t usnic_uiom_num_pages(struct usnic_uiom_reg *uiomr)
+{
+	return PAGE_ALIGN(uiomr->length + uiomr->offset) >> PAGE_SHIFT;
+}
 
-	task = get_pid_task(ucontext->tgid, PIDTYPE_PID);
-	if (!task)
-		goto out;
-	mm = get_task_mm(task);
-	put_task_struct(task);
-	if (!mm)
-		goto out;
+static void usnic_uiom_release_defer(struct work_struct *work)
+{
+	struct usnic_uiom_reg *uiomr =
+		container_of(work, struct usnic_uiom_reg, work);
 
-	diff = PAGE_ALIGN(uiomr->length + uiomr->offset) >> PAGE_SHIFT;
+	down_write(&uiomr->owning_mm->mmap_sem);
+	uiomr->owning_mm->pinned_vm -= usnic_uiom_num_pages(uiomr);
+	up_write(&uiomr->owning_mm->mmap_sem);
+
+	__usnic_uiom_release_tail(uiomr);
+}
+
+void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr,
+			    struct ib_ucontext *context)
+{
+	__usnic_uiom_reg_release(uiomr->pd, uiomr, 1);
 
 	/*
 	 * We may be called with the mm's mmap_sem already held.  This
@@ -456,25 +459,21 @@ void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr,
 	 * the last reference to our file and calls our release
 	 * method.  If there are memory regions to destroy, we'll end
 	 * up here and not be able to take the mmap_sem.  In that case
-	 * we defer the vm_locked accounting to the system workqueue.
+	 * we defer the vm_locked accounting to a workqueue.
 	 */
-	if (ucontext->closing) {
-		if (!down_write_trylock(&mm->mmap_sem)) {
-			INIT_WORK(&uiomr->work, usnic_uiom_reg_account);
-			uiomr->mm = mm;
-			uiomr->diff = diff;
-
+	if (context->closing) {
+		if (!down_write_trylock(&uiomr->owning_mm->mmap_sem)) {
+			INIT_WORK(&uiomr->work, usnic_uiom_release_defer);
 			queue_work(usnic_uiom_wq, &uiomr->work);
 			return;
 		}
-	} else
-		down_write(&mm->mmap_sem);
+	} else {
+		down_write(&uiomr->owning_mm->mmap_sem);
+	}
+	uiomr->owning_mm->pinned_vm -= usnic_uiom_num_pages(uiomr);
+	up_write(&uiomr->owning_mm->mmap_sem);
 
-	mm->pinned_vm -= diff;
-	up_write(&mm->mmap_sem);
-	mmput(mm);
-out:
-	kfree(uiomr);
+	__usnic_uiom_release_tail(uiomr);
 }
 
 struct usnic_uiom_pd *usnic_uiom_alloc_pd(void)

drivers/infiniband/hw/usnic/usnic_uiom.h

@@ -71,8 +71,7 @@ struct usnic_uiom_reg {
 	int				writable;
 	struct list_head		chunk_list;
 	struct work_struct		work;
-	struct mm_struct		*mm;
-	unsigned long			diff;
+	struct mm_struct		*owning_mm;
 };
 
 struct usnic_uiom_chunk {