From 0350276168942a9fb7540c03995229e3502976a2 Mon Sep 17 00:00:00 2001 From: Niklas Schnelle Date: Fri, 12 Feb 2021 10:16:46 +0100 Subject: [PATCH] s390/pci: use mutex not spinlock for zbus list In a later change we will first collect all PCI functions from the CLP List PCI functions call, then register them to/creating the relevant zbus. Then only after we've created our virtual bus structure will we scan all zbusses iterating over the zbus list. Since scanning is relatively slow a spinlock is a bad fit for protecting the loop over the devices on the zbus. Furthermore doing the probing on the bus we need to use pci_lock_rescan_remove() as devices are added to the PCI subsystem and that is a mutex which can't be locked nested inside a spinlock section. Note that the contention of this lock should be very low either way as zbusses are only added/removed concurrently on hotplug events. Reviewed-by: Matthew Rosato Reviewed-by: Pierre Morel Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens --- arch/s390/pci/pci_bus.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c index d200e7559725..9bc869afe011 100644 --- a/arch/s390/pci/pci_bus.c +++ b/arch/s390/pci/pci_bus.c @@ -27,7 +27,7 @@ #include "pci_iov.h" static LIST_HEAD(zbus_list); -static DEFINE_SPINLOCK(zbus_list_lock); +static DEFINE_MUTEX(zbus_list_lock); static int zpci_nb_devices; /* zpci_bus_prepare_device - Prepare a zPCI function for scanning @@ -214,9 +214,9 @@ static void zpci_bus_release(struct kref *kref) pci_unlock_rescan_remove(); } - spin_lock(&zbus_list_lock); + mutex_lock(&zbus_list_lock); list_del(&zbus->bus_next); - spin_unlock(&zbus_list_lock); + mutex_unlock(&zbus_list_lock); kfree(zbus); } @@ -229,7 +229,7 @@ static struct zpci_bus *zpci_bus_get(int pchid) { struct zpci_bus *zbus; - spin_lock(&zbus_list_lock); + mutex_lock(&zbus_list_lock); list_for_each_entry(zbus, &zbus_list, bus_next) { if (pchid == zbus->pchid) { kref_get(&zbus->kref); @@ -238,7 +238,7 @@ static struct zpci_bus *zpci_bus_get(int pchid) } zbus = NULL; out_unlock: - spin_unlock(&zbus_list_lock); + mutex_unlock(&zbus_list_lock); return zbus; } @@ -252,9 +252,9 @@ static struct zpci_bus *zpci_bus_alloc(int pchid) zbus->pchid = pchid; INIT_LIST_HEAD(&zbus->bus_next); - spin_lock(&zbus_list_lock); + mutex_lock(&zbus_list_lock); list_add_tail(&zbus->bus_next, &zbus_list); - spin_unlock(&zbus_list_lock); + mutex_unlock(&zbus_list_lock); kref_init(&zbus->kref); INIT_LIST_HEAD(&zbus->resources);