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iommufd: Improve a few unclear bits of code

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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: 8d160cd4d5 ("iommufd: Algorithms for PFN storage")
Link: https://lore.kernel.org/r/2-v1-0362a1a1c034+98-iommufd_fixes1_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe 2022-12-07 16:44:42 -04:00
parent c9b8a83a8f
commit a26fa39206
1 changed files with 5 additions and 2 deletions
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7
drivers/iommu/iommufd/pages.c
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@ -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;