PCI/P2PDMA: Annotate RCU dereference
A dereference of the __rcu pointer was noticed by sparse: drivers/pci/p2pdma.c:199:44: sparse: sparse: dereference of noderef expression Dereference the __rcu pointer using rcu_dereference_protected() instead of accessing it directly. It's safe to use rcu_dereference_protected() because a reference is held on the pgmap's percpu reference counter and thus it cannot disappear. Link: https://lore.kernel.org/r/20230209172953.4597-1-logang@deltatee.com Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
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@ -194,11 +194,13 @@ static const struct attribute_group p2pmem_group = {
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static void p2pdma_page_free(struct page *page)
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{
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struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap);
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/* safe to dereference while a reference is held to the percpu ref */
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struct pci_p2pdma *p2pdma =
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rcu_dereference_protected(pgmap->provider->p2pdma, 1);
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struct percpu_ref *ref;
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gen_pool_free_owner(pgmap->provider->p2pdma->pool,
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(uintptr_t)page_to_virt(page), PAGE_SIZE,
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(void **)&ref);
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gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page),
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PAGE_SIZE, (void **)&ref);
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percpu_ref_put(ref);
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}
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