Commit a26fa392 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

iommufd: Improve a few unclear bits of code 

Correct a few items noticed late in review:

 - We should assert that the math in batch_clear_carry() doesn't underflow

 - user->locked should be -1 not 0 sicne we just did mmput

 - npages should not have been recalculated, it already has that value

No functional change.

Fixes: 8d160cd4 ("iommufd: Algorithms for PFN storage")
Link: https://lore.kernel.org/r/2-v1-0362a1a1c034+98-iommufd_fixes1_jgg@nvidia.com


Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Reported-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent c9b8a83a

drivers/iommu/iommufd/pages.c

+5 −2
Original line number Diff line number Diff line
@@ -289,6 +289,10 @@ static void batch_clear_carry(struct pfn_batch *batch, unsigned int keep_pfns) 
	if (!keep_pfns)

		return batch_clear(batch);



	if (IS_ENABLED(CONFIG_IOMMUFD_TEST))

		WARN_ON(!batch->end ||

			batch->npfns[batch->end - 1] < keep_pfns);



	batch->total_pfns = keep_pfns;

	batch->npfns[0] = keep_pfns;

	batch->pfns[0] = batch->pfns[batch->end - 1] +
@@ -723,7 +727,7 @@ static void pfn_reader_user_destroy(struct pfn_reader_user *user, 
			mmap_read_unlock(pages->source_mm);

		if (pages->source_mm != current->mm)

			mmput(pages->source_mm);

		user->locked = 0;

		user->locked = -1;

	}



	kfree(user->upages);
@@ -810,7 +814,6 @@ static int incr_user_locked_vm(struct iopt_pages *pages, unsigned long npages) 


	lock_limit = task_rlimit(pages->source_task, RLIMIT_MEMLOCK) >>

		     PAGE_SHIFT;

	npages = pages->npinned - pages->last_npinned;

	do {

		cur_pages = atomic_long_read(&pages->source_user->locked_vm);

		new_pages = cur_pages + npages;