linux-kernel - [PATCH] pciehp: Remove a non-existent card, regardless of "surprise" capability

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Message-ID: <53041C9F.7050801@gmail.com>
Date:	Tue, 18 Feb 2014 18:53:19 -0800
From:	Rajat Jain <rajatxjain@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
CC:	Rajat Jain <rajatjain@...iper.net>,
	Guenter Roeck <groeck@...iper.net>,
	Alex Williamson <alex.williamson@...hat.com>
Subject: [PATCH] pciehp: Remove a non-existent card, regardless of "surprise"
 capability

In case a card is physically yanked out, it should immediately be
removed, regardless of the "surprise" capability bit. Thus:

* Always handle the physical removal - regardless of the "surprise" bit.
* Don't use "surprise" capability when making decisions about enabling
presence detect notifications.
* Reword the comments to indicate the intent.

Signed-off-by: Rajat Jain <rajatxjain@...il.com>
Signed-off-by: Rajat Jain <rajatjain@...iper.net>
Signed-off-by: Guenter Roeck <groeck@...iper.net>
---
 drivers/pci/hotplug/pciehp_ctrl.c |    9 ++++++++-
 drivers/pci/hotplug/pciehp_hpc.c  |    9 +++++----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index e027e36..c75e6a6 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -534,9 +534,16 @@ static void interrupt_event_handler(struct work_struct *work)
 		pciehp_green_led_off(p_slot);
 		break;
 	case INT_PRESENCE_ON:
-	case INT_PRESENCE_OFF:
 		if (!HP_SUPR_RM(ctrl))
 			break;
+		ctrl_dbg(ctrl, "Surprise Insertion\n");
+		handle_surprise_event(p_slot);
+		break;
+	case INT_PRESENCE_OFF:
+		/*
+		 * Regardless of surprise capability, we need to
+		 * definitely remove a card that has been pulled out!
+		 */
 		ctrl_dbg(ctrl, "Surprise Removal\n");
 		handle_surprise_event(p_slot);
 		break;
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index da4b020..d7d058f 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -619,9 +619,10 @@ static void pcie_disable_notification(struct controller *ctrl)
 
 /*
  * pciehp has a 1:1 bus:slot relationship so we ultimately want a secondary
- * bus reset of the bridge, but if the slot supports surprise removal (or
- * link state change based hotplug), we need to disable presence detection
- * (or link state notifications) around the bus reset and clear any spurious
+ * bus reset of the bridge, but at the same time we want to ensure that it is
+ * not seen as a hot-unplug, followed by the hot-plug of the device. Thus,
+ * disable link state notification and presence detection change notification
+ * momentarily, if we see that they could interfere. Also, clear any spurious
  * events after.
  */
 int pciehp_reset_slot(struct slot *slot, int probe)
@@ -633,7 +634,7 @@ int pciehp_reset_slot(struct slot *slot, int probe)
 	if (probe)
 		return 0;
 
-	if (HP_SUPR_RM(ctrl) && !ATTN_BUTTN(ctrl)) {
+	if (!ATTN_BUTTN(ctrl)) {
 		ctrl_mask |= PCI_EXP_SLTCTL_PDCE;
 		stat_mask |= PCI_EXP_SLTSTA_PDC;
 	}
-- 
1.7.9.5

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