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RDMA/umem: Minor optimizations 

Noticed while reviewing commit d4b4dd1b97 ("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 <dledford@redhat.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Doug Ledford 2018-09-21 11:30:12 -04:00 committed by Jason Gunthorpe
parent 1b571086e8
commit 3312d1c6bd
1 changed files with 7 additions and 8 deletions
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15
drivers/infiniband/core/umem.c
View File

@ -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(&current->mm->mmap_sem);
current->mm->pinned_vm -= ib_umem_num_pages(umem);
up_write(&current->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);