From 3312d1c6bdee6aa912c099c0ac0662d197c52842 Mon Sep 17 00:00:00 2001 From: Doug Ledford Date: Fri, 21 Sep 2018 11:30:12 -0400 Subject: [PATCH] RDMA/umem: Minor optimizations Noticed while reviewing commit d4b4dd1b9706 ("RDMA/umem: Do not use current->tgid to track the mm_struct") patch. Why would we take a lock, adjust a protected variable, drop the lock, and *then* check the input into our protected variable adjustment? Then we have to take the lock again on our error unwind. Let's just check the input early and skip taking the locks needlessly if the input isn't valid. It was also noticed that we set mm = current->mm, we then never modify mm, but we still go back and reference current->mm a number of times needlessly. Be consistent in using the stored reference in mm. Signed-off-by: Doug Ledford Reviewed-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/umem.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index fec5d489e311..1886d7709911 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -152,6 +152,10 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, umem->hugetlb = 0; npages = ib_umem_num_pages(umem); + if (npages == 0 || npages > UINT_MAX) { + ret = -EINVAL; + goto out; + } lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; @@ -166,11 +170,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, cur_base = addr & PAGE_MASK; - if (npages == 0 || npages > UINT_MAX) { - ret = -EINVAL; - goto vma; - } - ret = sg_alloc_table(&umem->sg_head, npages, GFP_KERNEL); if (ret) goto vma; @@ -224,9 +223,9 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, umem_release: __ib_umem_release(context->device, umem, 0); vma: - down_write(¤t->mm->mmap_sem); - current->mm->pinned_vm -= ib_umem_num_pages(umem); - up_write(¤t->mm->mmap_sem); + down_write(&mm->mmap_sem); + mm->pinned_vm -= ib_umem_num_pages(umem); + up_write(&mm->mmap_sem); out: if (vma_list) free_page((unsigned long) vma_list);