linux-kernel - [PATCH v5 10/12] PCI: endpoint: Make sure that BAR_5 does not have 64-bit flag set when clearing

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Date:   Wed, 28 Mar 2018 13:50:15 +0200
From:   Niklas Cassel <niklas.cassel@...s.com>
To:     kishon@...com, cyrille.pitchen@...e-electrons.com,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Niklas Cassel <niklass@...s.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v5 10/12] PCI: endpoint: Make sure that BAR_5 does not have 64-bit flag set when clearing

Since a 64-bit BAR consists of a BAR pair, and since there is no
BAR after BAR_5, BAR_5 cannot be 64-bits wide.

This sanity check is done in pci_epc_clear_bar(), so that we don't need
to do this sanity check in all epc->ops->clear_bar() implementations.

Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
---
Kishon made a review comment that he wanted this:
https://marc.info/?l=linux-kernel&m=152161168226203

Personally, I don't think that this check is needed,
since pci_epc_set_bar() already does this check,
and no one should modify the flags after pci_epc_set_bar()
has been called.

If everyone agrees, then this patch could be dropped.

 drivers/pci/endpoint/pci-epc-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index eccc942043cb..b0ee42739c3c 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -285,7 +285,9 @@ void pci_epc_clear_bar(struct pci_epc *epc, u8 func_no,
 {
 	unsigned long flags;
 
-	if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions)
+	if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions ||
+	    (epf_bar->barno == BAR_5 &&
+	     epf_bar->flags & PCI_BASE_ADDRESS_MEM_TYPE_64))
 		return;
 
 	if (!epc->ops->clear_bar)
-- 
2.14.2