linux-kernel - [RFC 2/2] PCI: acpiphp: slowdown hotplug if hotplugging multiple devices at a time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20231213003614.1648343-3-imammedo@redhat.com>
Date:   Wed, 13 Dec 2023 01:36:14 +0100
From:   Igor Mammedov <imammedo@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dongli Zhang <dongli.zhang@...cle.com>, linux-acpi@...r.kernel.org,
        linux-pci@...r.kernel.org, imammedo@...hat.com, mst@...hat.com,
        rafael@...nel.org, lenb@...nel.org, bhelgaas@...gle.com,
        mika.westerberg@...ux.intel.com, boris.ostrovsky@...cle.com,
        joe.jin@...cle.com, stable@...r.kernel.org,
        Fiona Ebner <f.ebner@...xmox.com>,
        Thomas Lamprecht <t.lamprecht@...xmox.com>
Subject: [RFC 2/2] PCI: acpiphp: slowdown hotplug if hotplugging multiple devices at a time

previous commit ("PCI: acpiphp: enable slot only if it hasn't been enabled already"
introduced a workaround to avoid a race between SCSI_SCAN_ASYNC job and
bridge reconfiguration in case of single HBA hotplug.
However in virt environment it's possible to pause machine hotplug several
HBAs and let machine run. That can hit the same race when 2nd hotplugged
HBA will start re-configuring bridge.
Do the same thing as SHPC and throttle down hotplug of 2nd and up
devices within single hotplug event.

Signed-off-by: Igor Mammedov <imammedo@...hat.com>
---
 drivers/pci/hotplug/acpiphp_glue.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 6b11609927d6..30bca2086b24 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -37,6 +37,7 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
+#include <linux/delay.h>
 
 #include "../pci.h"
 #include "acpiphp.h"
@@ -700,6 +701,7 @@ static void trim_stale_devices(struct pci_dev *dev)
 static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
 {
 	struct acpiphp_slot *slot;
+        int nr_hp_slots = 0;
 
 	/* Bail out if the bridge is going away. */
 	if (bridge->is_going_away)
@@ -723,6 +725,10 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
 
 			/* configure all functions */
 			if (slot->flags != SLOT_ENABLED) {
+				if (nr_hp_slots)
+					msleep(1000);
+
+                                ++nr_hp_slots;
 				enable_slot(slot, true);
 			}
 		} else {
-- 
2.39.3