From 9d8ba74a181b1c81def21168795ed96cbe6f05ed Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Fri, 10 Feb 2023 14:46:39 +0100
Subject: [PATCH] PCI: Fix dropping valid root bus resources with .end = zero
Git-commit: 9d8ba74a181b1c81def21168795ed96cbe6f05ed
Patch-mainline: v6.3-rc1
References: git-fixes

On r8a7791/koelsch:

  kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
  # cat /sys/kernel/debug/kmemleak
  unreferenced object 0xc3a34e00 (size 64):
    comm "swapper/0", pid 1, jiffies 4294937460 (age 199.080s)
    hex dump (first 32 bytes):
      b4 5d 81 f0 b4 5d 81 f0 c0 b0 a2 c3 00 00 00 00  .]...]..........
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    backtrace:
      [<fe3aa979>] __kmalloc+0xf0/0x140
      [<34bd6bc0>] resource_list_create_entry+0x18/0x38
      [<767046bc>] pci_add_resource_offset+0x20/0x68
      [<b3f3edf2>] devm_of_pci_get_host_bridge_resources.constprop.0+0xb0/0x390

When coalescing two resources for a contiguous aperture, the second
resource is enlarged to cover the full contiguous range, while the first
resource is marked invalid.  This invalidation is done by clearing the
flags, start, and end members.

When adding the initial resources to the bus later, invalid resources are
skipped.  Unfortunately, the check for an invalid resource considers only
the end member, causing false positives.

E.g. on r8a7791/koelsch, root bus resource 0 ("bus 00") is skipped, and no
longer registered with pci_bus_insert_busn_res() (causing the memory leak),
nor printed:

   pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges:
   pci-rcar-gen2 ee090000.pci:      MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000
   pci-rcar-gen2 ee090000.pci: PCI: revision 11
   pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00
  -pci_bus 0000:00: root bus resource [bus 00]
   pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff]

Fix this by only skipping resources where all of the flags, start, and end
members are zero.

Fixes: 7c3855c423b17f6c ("PCI: Coalesce host bridge contiguous apertures")
Link: https://lore.kernel.org/r/da0fcd5e86c74239be79c7cb03651c0fce31b515.1676036673.git.geert+renesas@glider.be
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1779582fb500..598858482548 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -996,7 +996,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	resource_list_for_each_entry_safe(window, n, &resources) {
 		offset = window->offset;
 		res = window->res;
-		if (!res->end)
+		if (!res->flags && !res->start && !res->end)
 			continue;
 
 		list_move_tail(&window->node, &bridge->windows);
-- 
2.35.3