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authorLogan Gunthorpe <logang@deltatee.com>2023-02-09 20:29:53 +0300
committerBjorn Helgaas <bhelgaas@google.com>2023-02-17 01:31:12 +0300
commit6606f4c3c48c7a75b13816266d3ea562eeec0b44 (patch)
tree28f9cd67b7e5029d3e5edf1d8907a965b365491a /drivers/pci
parent1b929c02afd37871d5afb9d498426f83432e71c2 (diff)
downloadlinux-6606f4c3c48c7a75b13816266d3ea562eeec0b44.tar.xz
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>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/p2pdma.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 86812d2073ea..9e8205572830 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -194,11 +194,13 @@ static const struct attribute_group p2pmem_group = {
static void p2pdma_page_free(struct page *page)
{
struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap);
+ /* safe to dereference while a reference is held to the percpu ref */
+ struct pci_p2pdma *p2pdma =
+ rcu_dereference_protected(pgmap->provider->p2pdma, 1);
struct percpu_ref *ref;
- gen_pool_free_owner(pgmap->provider->p2pdma->pool,
- (uintptr_t)page_to_virt(page), PAGE_SIZE,
- (void **)&ref);
+ gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page),
+ PAGE_SIZE, (void **)&ref);
percpu_ref_put(ref);
}