[PATCH] PCI: pciehp: Prevent child devices from doing RPM on PCIe Link Down

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

When inserting an SD7.0 card to Realtek card reader, it can trigger PCI
slot Link down and causes the following error:
[   63.898861] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
[   63.912118] BUG: unable to handle page fault for address: ffffb24d403e5010
[   63.912122] #PF: supervisor read access in kernel mode
[   63.912125] #PF: error_code(0x0000) - not-present page
[   63.912126] PGD 100000067 P4D 100000067 PUD 1001fe067 PMD 100d97067 PTE 0
[   63.912131] Oops: 0000 [#1] PREEMPT SMP PTI
[   63.912134] CPU: 3 PID: 534 Comm: kworker/3:10 Not tainted 6.4.0 #6
[   63.912137] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./H370M Pro4, BIOS P3.40 10/25/2018
[   63.912138] Workqueue: pm pm_runtime_work
[   63.912144] RIP: 0010:ioread32+0x2e/0x70
[   63.912148] Code: ff 03 00 77 25 48 81 ff 00 00 01 00 77 14 8b 15 08 d9 54 01 b8 ff ff ff ff 85 d2 75 14 c3 cc cc cc cc 89 fa ed c3 cc cc cc cc <8b> 07 c3 cc cc cc cc 55 83 ea 01 48 89 fe 48 c7 c7 98 6f 15 99 48
[   63.912150] RSP: 0018:ffffb24d40a5bd78 EFLAGS: 00010296
[   63.912152] RAX: ffffb24d403e5000 RBX: 0000000000000152 RCX: 000000000000007f
[   63.912153] RDX: 000000000000ff00 RSI: ffffb24d403e5010 RDI: ffffb24d403e5010
[   63.912155] RBP: ffffb24d40a5bd98 R08: ffffb24d403e5010 R09: 0000000000000000
[   63.912156] R10: ffff9074cd95e7f4 R11: 0000000000000003 R12: 000000000000007f
[   63.912158] R13: ffff9074e1a68c00 R14: ffff9074e1a68d00 R15: 0000000000009003
[   63.912159] FS:  0000000000000000(0000) GS:ffff90752a180000(0000) knlGS:0000000000000000
[   63.912161] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   63.912162] CR2: ffffb24d403e5010 CR3: 0000000152832006 CR4: 00000000003706e0
[   63.912164] Call Trace:
[   63.912165]  <TASK>
[   63.912167]  ? show_regs+0x68/0x70
[   63.912171]  ? __die_body+0x20/0x70
[   63.912173]  ? __die+0x2b/0x40
[   63.912175]  ? page_fault_oops+0x160/0x480
[   63.912177]  ? search_bpf_extables+0x63/0x90
[   63.912180]  ? ioread32+0x2e/0x70
[   63.912183]  ? search_exception_tables+0x5f/0x70
[   63.912186]  ? kernelmode_fixup_or_oops+0xa2/0x120
[   63.912189]  ? __bad_area_nosemaphore+0x179/0x230
[   63.912191]  ? bad_area_nosemaphore+0x16/0x20
[   63.912193]  ? do_kern_addr_fault+0x8b/0xa0
[   63.912195]  ? exc_page_fault+0xe5/0x180
[   63.912198]  ? asm_exc_page_fault+0x27/0x30
[   63.912203]  ? ioread32+0x2e/0x70
[   63.912206]  ? rtsx_pci_write_register+0x5b/0x90 [rtsx_pci]
[   63.912217]  rtsx_set_l1off_sub+0x1c/0x30 [rtsx_pci]
[   63.912226]  rts5261_set_l1off_cfg_sub_d0+0x36/0x40 [rtsx_pci]
[   63.912234]  rtsx_pci_runtime_idle+0xc7/0x160 [rtsx_pci]
[   63.912243]  ? __pfx_pci_pm_runtime_idle+0x10/0x10
[   63.912246]  pci_pm_runtime_idle+0x34/0x70
[   63.912248]  rpm_idle+0xc4/0x2b0
[   63.912251]  pm_runtime_work+0x93/0xc0
[   63.912254]  process_one_work+0x21a/0x430
[   63.912258]  worker_thread+0x4a/0x3c0
[   63.912261]  ? __pfx_worker_thread+0x10/0x10
[   63.912263]  kthread+0x106/0x140
[   63.912266]  ? __pfx_kthread+0x10/0x10
[   63.912268]  ret_from_fork+0x29/0x50
[   63.912273]  </TASK>
[   63.912274] Modules linked in: nvme nvme_core snd_hda_codec_hdmi snd_sof_pci_intel_cnl snd_sof_intel_hda_common snd_hda_codec_realtek snd_hda_codec_generic snd_soc_hdac_hda soundwire_intel ledtrig_audio nls_iso8859_1 soundwire_generic_allocation soundwire_cadence snd_sof_intel_hda_mlink snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof snd_sof_utils snd_hda_ext_core snd_soc_acpi_intel_match snd_soc_acpi soundwire_bus snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine snd_hda_intel i915 snd_intel_dspcfg snd_intel_sdw_acpi intel_rapl_msr snd_hda_codec intel_rapl_common snd_hda_core x86_pkg_temp_thermal intel_powerclamp snd_hwdep coretemp snd_pcm kvm_intel drm_buddy ttm mei_hdcp kvm drm_display_helper snd_seq_midi snd_seq_midi_event cec crct10dif_pclmul ghash_clmulni_intel sha512_ssse3 aesni_intel crypto_simd rc_core cryptd rapl snd_rawmidi drm_kms_helper binfmt_misc intel_cstate i2c_algo_bit joydev snd_seq snd_seq_device syscopyarea wmi_bmof snd_timer sysfillrect input_leds snd ee1004 sysimgblt mei_me soundcore
[   63.912324]  mei intel_pch_thermal mac_hid acpi_tad acpi_pad sch_fq_codel msr parport_pc ppdev lp ramoops drm parport reed_solomon efi_pstore ip_tables x_tables autofs4 hid_generic usbhid hid rtsx_pci_sdmmc crc32_pclmul ahci e1000e i2c_i801 i2c_smbus rtsx_pci xhci_pci libahci xhci_pci_renesas video wmi
[   63.912346] CR2: ffffb24d403e5010
[   63.912348] ---[ end trace 0000000000000000 ]---

This happens because scheduled pm_runtime_idle() is not cancelled.

So use pm_runtime_barrier() to ensure all devices on the bus stops
runtime power management actions.

Link: https://lore.kernel.org/all/2ce258f371234b1f8a1a470d5488d00e@realtek.com/
Tested-by: Ricky Wu <ricky_wu@realtek.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/pci/hotplug/pciehp_pci.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/hotplug/pciehp_pci.c b/drivers/pci/hotplug/pciehp_pci.c
index ad12515a4a12..9ae4fa95c8c1 100644
--- a/drivers/pci/hotplug/pciehp_pci.c
+++ b/drivers/pci/hotplug/pciehp_pci.c
@@ -18,9 +18,18 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 #include "../pci.h"
 #include "pciehp.h"
 
+int pci_dev_disconnect(struct pci_dev *pdev, void *unused)
+{
+	pm_runtime_barrier(&pdev->dev);
+	pci_dev_set_disconnected(pdev, NULL);
+
+	return 0;
+}
+
 /**
  * pciehp_configure_device() - enumerate PCI devices below a hotplug bridge
  * @ctrl: PCIe hotplug controller
@@ -98,7 +107,7 @@ void pciehp_unconfigure_device(struct controller *ctrl, bool presence)
 		 __func__, pci_domain_nr(parent), parent->number);
 
 	if (!presence)
-		pci_walk_bus(parent, pci_dev_set_disconnected, NULL);
+		pci_walk_bus(parent, pci_dev_disconnect, NULL);
 
 	pci_lock_rescan_remove();
 
-- 
2.34.1