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drivers/IB,hfi1: do not se mmap_sem 

This driver already uses gup_fast() and thus we can just drop the mmap_sem
protection around the pinned_vm counter. Note that the window between when
hfi1_can_pin_pages() is called and the actual counter is incremented
remains the same as mmap_sem was _only_ used for when ->pinned_vm was
touched.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.det>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Davidlohr Bueso 2019-02-06 09:59:18 -08:00 committed by Jason Gunthorpe
parent 3a2a1e9056
commit 0e15c25336
1 changed files with 0 additions and 6 deletions
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6
drivers/infiniband/hw/hfi1/user_pages.c
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@ -91,9 +91,7 @@ bool hfi1_can_pin_pages(struct hfi1_devdata *dd, struct mm_struct *mm,
/* Convert to number of pages */
size = DIV_ROUND_UP(size, PAGE_SIZE);
down_read(&mm->mmap_sem);
pinned = atomic64_read(&mm->pinned_vm);
up_read(&mm->mmap_sem);
/* First, check the absolute limit against all pinned pages. */
if (pinned + npages >= ulimit && !can_lock)
@ -111,9 +109,7 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np
if (ret < 0)
return ret;
down_write(&mm->mmap_sem);
atomic64_add(ret, &mm->pinned_vm);
up_write(&mm->mmap_sem);
return ret;
}
@ -130,8 +126,6 @@ void hfi1_release_user_pages(struct mm_struct *mm, struct page **p,
}
if (mm) { /* during close after signal, mm can be NULL */
down_write(&mm->mmap_sem);
atomic64_sub(npages, &mm->pinned_vm);
up_write(&mm->mmap_sem);
}
}