[PATCH v6 01/30] PCI: Rip out pci_bus_add_devices() from pci_scan_bus()

[Yijing Wang]

Pci_bus_add_devices() should not be placed in pci_scan_bus().
Now pci device will be added to driver core once its
creation. All things left in pci_bus_add_devices() are
driver attachment and other trivial sysfs things.
Pci_scan_bus() should be the function responsible for
scanning PCI devices, not including driver attachment.
Other, some callers(m68k,unicore32,alpha) of pci_scan_bus()
will call pci_bus_size_bridges() and pci_bus_assign_resources()
after pci_scan_bus().

E.g.
In m68k
mcf_pci_init()
	pci_scan_bus()
		...
		pci_bus_add_devices() --- try to attach driver
	pci_fixup_irqs()
	pci_bus_size_bridges()
	pci_bus_assign_resources()

Above code flow make pci scan logic obscure, resources should
be assigned correctly before attaching driver. Because
pci_scan_bus() mostly be called in system boot path, when
before drivers are loaded(in module_init), so no pci scan
issues will occur. Most pci_scan_bus() callers additionally
call pci_bus_size_bridges() and pci_bus_assign_resources()
after pci_scan_bus(), we could rip out pci_bus_add_devices()
for better code readability. After applied this patch,
pci_scan_bus() should be used like:

pci_scan_bus() (mandatory)
pci_fixup_irqs() (optional)
pci_bus_size_bridges() (optional)
pci_pci_bus_assign_resources() (optional)
pci_bus_add_devices() (mandatory)

Signed-off-by: Yijing Wang <wangyijing at huawei.com>
CC: "David S. Miller" <davem at davemloft.net>
CC: Geert Uytterhoeven <geert at linux-m68k.org>
CC: Guan Xuetao <gxt at mprc.pku.edu.cn>
CC: Richard Henderson <rth at twiddle.net>
CC: Ivan Kokshaysky <ink at jurassic.park.msu.ru>
CC: Matt Turner <mattst88 at gmail.com>
CC: linux-alpha at vger.kernel.org
CC: linux-m68k at lists.linux-m68k.org
CC: sparclinux at vger.kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
---
 arch/alpha/kernel/sys_nautilus.c  |    4 ++++
 arch/m68k/coldfire/pci.c          |    1 +
 arch/sparc/kernel/pcic.c          |    3 +++
 arch/unicore32/kernel/pci.c       |   11 +++--------
 drivers/pci/hotplug/ibmphp_core.c |    8 ++++++--
 drivers/pci/probe.c               |    1 -
 6 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/arch/alpha/kernel/sys_nautilus.c b/arch/alpha/kernel/sys_nautilus.c
index 837c0fa..700686d 100644
--- a/arch/alpha/kernel/sys_nautilus.c
+++ b/arch/alpha/kernel/sys_nautilus.c
@@ -207,6 +207,9 @@ nautilus_init_pci(void)
 
 	/* Scan our single hose.  */
 	bus = pci_scan_bus(0, alpha_mv.pci_ops, hose);
+	if (!bus)
+		return;
+
 	hose->bus = bus;
 	pcibios_claim_one_bus(bus);
 
@@ -253,6 +256,7 @@ nautilus_init_pci(void)
 	   for the root bus, so just clear it. */
 	bus->self = NULL;
 	pci_fixup_irqs(alpha_mv.pci_swizzle, alpha_mv.pci_map_irq);
+	pci_bus_add_devices(bus);
 }
 
 /*
diff --git a/arch/m68k/coldfire/pci.c b/arch/m68k/coldfire/pci.c
index df96792..d45f087 100644
--- a/arch/m68k/coldfire/pci.c
+++ b/arch/m68k/coldfire/pci.c
@@ -319,6 +319,7 @@ static int __init mcf_pci_init(void)
 	pci_fixup_irqs(pci_common_swizzle, mcf_pci_map_irq);
 	pci_bus_size_bridges(rootbus);
 	pci_bus_assign_resources(rootbus);
+	pci_bus_add_devices(rootbus);
 	return 0;
 }
 
diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c
index 6cc78c2..0f4dc6b 100644
--- a/arch/sparc/kernel/pcic.c
+++ b/arch/sparc/kernel/pcic.c
@@ -391,12 +391,15 @@ static void __init pcic_pbm_scan_bus(struct linux_pcic *pcic)
 	struct linux_pbm_info *pbm = &pcic->pbm;
 
 	pbm->pci_bus = pci_scan_bus(pbm->pci_first_busno, &pcic_ops, pbm);
+	if (!pbm->pci_bus)
+		return;
 #if 0 /* deadwood transplanted from sparc64 */
 	pci_fill_in_pbm_cookies(pbm->pci_bus, pbm, pbm->prom_node);
 	pci_record_assignments(pbm, pbm->pci_bus);
 	pci_assign_unassigned(pbm, pbm->pci_bus);
 	pci_fixup_irq(pbm, pbm->pci_bus);
 #endif
+	pci_bus_add_devices(pbm->pci_bus);
 }
 
 /*
diff --git a/arch/unicore32/kernel/pci.c b/arch/unicore32/kernel/pci.c
index 374a055..3d82024 100644
--- a/arch/unicore32/kernel/pci.c
+++ b/arch/unicore32/kernel/pci.c
@@ -266,17 +266,12 @@ static int __init pci_common_init(void)
 	pci_fixup_irqs(pci_common_swizzle, pci_puv3_map_irq);
 
 	if (!pci_has_flag(PCI_PROBE_ONLY)) {
-		/*
-		 * Size the bridge windows.
-		 */
+		/* Size the bridge windows. */
 		pci_bus_size_bridges(puv3_bus);
-
-		/*
-		 * Assign resources.
-		 */
+		/* Assign resources. */
 		pci_bus_assign_resources(puv3_bus);
 	}
-
+	pci_bus_add_devices(puv3_bus);
 	return 0;
 }
 subsys_initcall(pci_common_init);
diff --git a/drivers/pci/hotplug/ibmphp_core.c b/drivers/pci/hotplug/ibmphp_core.c
index 96c5c72..1530247 100644
--- a/drivers/pci/hotplug/ibmphp_core.c
+++ b/drivers/pci/hotplug/ibmphp_core.c
@@ -738,7 +738,7 @@ static void ibm_unconfigure_device(struct pci_func *func)
  */
 static u8 bus_structure_fixup(u8 busno)
 {
-	struct pci_bus *bus;
+	struct pci_bus *bus, *b;
 	struct pci_dev *dev;
 	u16 l;
 
@@ -765,7 +765,11 @@ static u8 bus_structure_fixup(u8 busno)
 					(l != 0x0000) && (l != 0xffff)) {
 			debug("%s - Inside bus_structure_fixup()\n",
 							__func__);
-			pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
+			b = pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
+			if (!b)
+				continue;
+
+			pci_bus_add_devices(b);
 			break;
 		}
 	}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8d2f400..88604f2 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2123,7 +2123,6 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
 	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
 	if (b) {
 		pci_scan_child_bus(b);
-		pci_bus_add_devices(b);
 	} else {
 		pci_free_resource_list(&resources);
 	}
-- 
1.7.1