linux-kernel - [PATCHv2] PCI: pciehp: Use appropriate conditions to check the hotplug controller status

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Date: Tue, 28 May 2024 14:42:00 +0800
From: Bitao Hu <yaoma@...ux.alibaba.com>
To: lukas@...ner.de,
	bhelgaas@...gle.com,
	weirongguang@...inos.cn
Cc: linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	kanie@...ux.alibaba.com,
	yaoma@...ux.alibaba.com
Subject: [PATCHv2] PCI: pciehp: Use appropriate conditions to check the hotplug controller status

"present" and "link_active" can be 1 if the status is ready, and 0 if
it is not. Both of them can be -ENODEV if reading the config space
of the hotplug port failed. That's typically the case if the hotplug
port itself was hot-removed. Therefore, this situation can occur:
pciehp_card_present() may return 1 and pciehp_check_link_active()
may return -ENODEV because the hotplug port was hot-removed in-between
the two function calls. In that case we'll emit both "Card present"
*and* "Link Up" since both 1 and -ENODEV are considered "true". This
is not the expected behavior. Those messages should be emited when
"present" and "link_active" are positive.

Signed-off-by: Bitao Hu <yaoma@...ux.alibaba.com>
Reviewed-by: Lukas Wunner <lukas@...ner.de>
---
v1 -> v2:
1. Explain the rationale of the code change in the commit message
more clearly.
2. Add the "Reviewed-by" tag of Lukas.
---
 drivers/pci/hotplug/pciehp_ctrl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index dcdbfcf404dd..6adfdbb70150 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -276,10 +276,10 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
 	case OFF_STATE:
 		ctrl->state = POWERON_STATE;
 		mutex_unlock(&ctrl->state_lock);
-		if (present)
+		if (present > 0)
 			ctrl_info(ctrl, "Slot(%s): Card present\n",
 				  slot_name(ctrl));
-		if (link_active)
+		if (link_active > 0)
 			ctrl_info(ctrl, "Slot(%s): Link Up\n",
 				  slot_name(ctrl));
 		ctrl->request_result = pciehp_enable_slot(ctrl);
-- 
2.37.1 (Apple Git-137.1)