linux-kernel - [PATCH v2 1/2] PCI: endpoint: Fix that API devm_pci_epc_destroy() fails to destroy the EPC device

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Message-Id: <20241102-pci-epc-core_fix-v2-1-0785f8435be5@quicinc.com>
Date: Sat, 02 Nov 2024 20:20:06 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Krzysztof Wilczyński <kw@...ux.com>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, Joao Pinto <jpinto@...opsys.com>
Cc: Zijun Hu <zijun_hu@...oud.com>, linux-pci@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Zijun Hu <quic_zijuhu@...cinc.com>, 
 stable@...r.kernel.org
Subject: [PATCH v2 1/2] PCI: endpoint: Fix that API devm_pci_epc_destroy()
 fails to destroy the EPC device

From: Zijun Hu <quic_zijuhu@...cinc.com>

For devm_pci_epc_destroy(), its comment says it needs to destroy the EPC
device, but it will not actually do that since devres_destroy() does not
call devm_pci_epc_release(), and it also can not fully undo what the API
devm_pci_epc_create() does, so it is faulty.

Fortunately, the faulty API has not been used by current kernel tree.
Fixed by using devres_release() instead of devres_destroy() within the API.

Fixes: 5e8cb4033807 ("PCI: endpoint: Add EP core layer to enable EP controller and EP functions")
Cc: stable@...r.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>

---
Below linux-next commit fixes a similar issue.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=fdce49b5da6e0fb6d077986dec3e90ef2b094b50

Why to fix the API here instead of directly deleting it?

1) it is simpler, just one line change.
2) it may be used in future.
3) ensure this restored API right if need to restore it in future
   after deleting.

Anyone may remove such APIs separately later if he/she cares.
---
 drivers/pci/endpoint/pci-epc-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 17f007109255..71b6d100056e 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -857,7 +857,7 @@ void devm_pci_epc_destroy(struct device *dev, struct pci_epc *epc)
 {
 	int r;
 
-	r = devres_destroy(dev, devm_pci_epc_release, devm_pci_epc_match,
+	r = devres_release(dev, devm_pci_epc_release, devm_pci_epc_match,
 			   epc);
 	dev_WARN_ONCE(dev, r, "couldn't find PCI EPC resource\n");
 }

-- 
2.34.1