FAILED: patch "[PATCH] PCI: endpoint: Clear secondary (not primary) EPC in" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 688d2eb4c6fcfdcdaed0592f9df9196573ff5ce2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024120648-rigging-lying-eda9@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 688d2eb4c6fcfdcdaed0592f9df9196573ff5ce2 Mon Sep 17 00:00:00 2001
From: Zijun Hu <quic_zijuhu@quicinc.com>
Date: Thu, 7 Nov 2024 08:53:09 +0800
Subject: [PATCH] PCI: endpoint: Clear secondary (not primary) EPC in
 pci_epc_remove_epf()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

In addition to a primary endpoint controller, an endpoint function may be
associated with a secondary endpoint controller, epf->sec_epc, to provide
NTB (non-transparent bridge) functionality.

Previously, pci_epc_remove_epf() incorrectly cleared epf->epc instead of
epf->sec_epc when removing from the secondary endpoint controller.

Extend the epc->list_lock coverage and clear either epf->epc or
epf->sec_epc as indicated.

Link: https://lore.kernel.org/r/20241107-epc_rfc-v2-2-da5b6a99a66f@quicinc.com
Fixes: 63840ff53223 ("PCI: endpoint: Add support to associate secondary EPC with EPF")
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[mani: reworded subject and description]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 21af2dbacc33..bed7c7d1fe3c 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -746,18 +746,18 @@ void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
 	if (IS_ERR_OR_NULL(epc) || !epf)
 		return;
 
+	mutex_lock(&epc->list_lock);
 	if (type == PRIMARY_INTERFACE) {
 		func_no = epf->func_no;
 		list = &epf->list;
+		epf->epc = NULL;
 	} else {
 		func_no = epf->sec_epc_func_no;
 		list = &epf->sec_epc_list;
+		epf->sec_epc = NULL;
 	}
-
-	mutex_lock(&epc->list_lock);
 	clear_bit(func_no, &epc->function_num_map);
 	list_del(list);
-	epf->epc = NULL;
 	mutex_unlock(&epc->list_lock);
 }
 EXPORT_SYMBOL_GPL(pci_epc_remove_epf);