Unbind the native serial driver error

Start with drivers/pci/msi.c around free_msi_irqs at line 375, then follow the reported pci_disable_msi and device-driver-detach path triggered by the sysfs unbind operation. Reproduce the failure on the reported BCM2711 setup with the native serial driver and custom PCI/PCIe UART drivers. Done means unbinding no longer causes the kernel BUG or userspace segmentation fault.

When i load custom PCI/PCIe UART drivers,something goes wrong.

The pi info:

When i unbind the native serial driver.It print message"Segmentation fault"

kernel log

• [00.598965] printk: console [ttyS0] disabled

• [00.607696] ------------[ cut here ]------------

• [00.607705] kernel BUG at drivers/pci/msi.c:375!

• [00.607710] Internal error: Oops - BUG: 0 [#1] SMP ARM

• [00.607722] Modules linked in: fuse sha256_generic libsha256 cfg80211 rfkill 8021q garp stp llc vc4 cec bcm2835_isp(C) bcm2835_v4l2(C) bcm2835_codec(C) bcm2835_mmal_vchiq(C) v4l2_mem2mem videobuf2_dma_contig videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common drm_kms_helper v3d videodev vc_sm_cma(C) gpu_sched mc snd_soc_core snd_bcm2835(C) drm drm_panel_orientation_quirks dwc2 snd_compress snd_pcm_dmaengine snd_pcm raspberrypi_hwmon snd_timer snd syscopyarea sysfillrect sysimgblt fb_sys_fops rpivid_mem uio_pdrv_genirq uio i2c_dev ip_tables x_tables ipv6

• [00.607883] CPU: 3 PID: 798 Comm: bash Tainted: G C 5.4.79-rt44-v7l #12

• [00.607891] Hardware name: BCM2711

• [00.607895] PC is at free_msi_irqs+0x174/0x194

• [00.607919] LR is at 0xef400130

• [00.607928] pc : [] lr : [] psr: a0000013

• [00.607933] sp : d534bd10 ip : ef40022c fp : d534bd3c

• [00.607937] r10: 00000000 r9 : d534bd94 r8 : ef072600

• [00.607942] r7 : ef856000 r6 : ef8561b4 r5 : 00000000 r4 : ef071a00

• [00.607946] r3 : ef298dc0 r2 : 00000000 r1 : 0000003a r0 : ef008d00

• [00.607951] Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user

• [00.607961] Control: 30c5383d Table: 153c0a00 DAC: 55555555

• [00.607965] Process bash (pid: 798, stack limit = 0xf1a73058)

• [00.607974] Stack: (0xd534bd10 to 0xd534c000)

• [00.607983] bd00: 00000039 c1205008 ef856000 ef071a00

• [00.607992] bd20: ef856000 ef072600 d534bd94 00000000 d534bd64 d534bd40 c0708910 c07080ac

• [00.608000] bd40: 00802600 f323a191 d534bd84 ef856078 ef072640 00000005 d534bd84 d534bd68

• [00.608008] bd60: c06ef314 c070880c ef856078 c1205008 00000005 d534bd94 d534bdcc d534bd88

• [00.608015] bd80: c0799308 c06ef244 d534bdb4 a0000013 c031fd4c ef072600 ef072400 f323a191

• [00.608022] bda0: c126fb98 ef856078 ef855878 c126fb98 ef856078 d53f5840 d534bf58 d4d99210

• [00.608029] bdc0: d534bde4 d534bdd0 c07994a4 c0799144 ef856078 ef855878 d534be04 d534bde8

• [00.608036] bde0: c079545c c0799470 c1268ac0 0000000c c126fb98 ef856078 d534be14 d534be08

• [00.608044] be00: c0795540 c0795358 d534be34 d534be18 c07933fc c079552c c079338c d4d99200

• [00.608051] be20: 00000000 00000000 d534be4c d534be38 c07927c8 c0793398 c0792798 d4d99200

• [00.608058] be40: d534be64 d534be50 c04a9fc4 c07927a4 0000000c d4d99200 d534be9c d534be68

• [00.608065] be60: c04a97ec c04a9f88 00000000 00000000 00000040 c1205008 d5cdd540 c04a9700

• [00.608072] be80: d534bf58 00000000 0000000c 0000000c d534bf24 d534bea0 c040a8d8 c04a970c

• [00.608080] bea0: ffece000 e468af5f d5a0ea00 00000000 d59f04e0 00000055 00000cc0 c040c438

• [00.608087] bec0: 0115e000 d5986040 d53c0a00 0000000c 00000000 c0a91288 00000000 d77a4188

• [00.608094] bee0: d534bf04 d534bef0 c0a91288 c0295740 00000000 f323a191 d534bf24 0000000c

• [00.608102] bf00: d5cdd540 0115d118 d534bf58 00000000 0115d118 0000000c d534bf54 d534bf28

• [00.608109] bf20: c040d828 c040a89c c020cf54 c0430d70 d534bf54 c1205008 d5cdd540 00000000

• [00.608116] bf40: 00000000 d5cdd540 d534bf94 d534bf58 c040dafc c040d780 00000000 00000000

• [00.608124] bf60: b6f31258 f323a191 d534bfac 0000000c 0115d118 b6f31d90 00000004 c02011c4

• [00.608131] bf80: d534a000 00000004 d534bfa4 d534bf98 c040db8c c040daa0 00000000 d534bfa8

• [00.608138] bfa0: c0201000 c040db80 0000000c 0115d118 00000001 0115d118 0000000c 00000000

• [00.608145] bfc0: 0000000c 0115d118 b6f31d90 00000004 0115d118 0000000c 001042a8 00000000

• [00.608153] bfe0: 0000006c be8c8f08 b6e507b8 b6eac944 60000010 00000001 00000000 00000000

• [00.608157] Backtrace:

• [00.608163] [] (free_msi_irqs) from [] (pci_disable_msi+0x110/0x12c)

• [00.608185] r10:00000000 r9:d534bd94 r8:ef072600 r7:ef856000 r6:ef071a00 r5:ef856000

• [00.608190] r4:c1205008 r3:00000039

• [00.608193] [] (pci_disable_msi) from [] (pcim_release+0xdc/0xe4)

• [00.608214] r6:00000005 r5:ef072640 r4:ef856078

• [00.608217] [] (pcim_release) from [] (release_nodes+0x1d0/0x214)

• [00.608233] r7:d534bd94 r6:00000005 r5:c1205008 r4:ef856078

• [00.608236] [] (release_nodes) from [] (devres_release_all+0x40/0x60)

• [00.608251] r10:d4d99210 r9:d534bf58 r8:d53f5840 r7:ef856078 r6:c126fb98 r5:ef855878

• [00.608255] r4:ef856078

• [00.608258] [] (devres_release_all) from [] (device_release_driver_internal+0x110/0x1b0)

• [00.608274] r5:ef855878 r4:ef856078

• [00.608277] [] (device_release_driver_internal) from [] (device_driver_detach+0x20/0x24)

• [00.608292] r7:ef856078 r6:c126fb98 r5:0000000c r4:c1268ac0

• [00.608296] [] (device_driver_detach) from [] (unbind_store+0x70/0xe4)

• [00.608310] [] (unbind_store) from [] (drv_attr_store+0x30/0x3c)

• [00.608323] r7:00000000 r6:00000000 r5:d4d99200 r4:c079338c

• [00.608325] [] (drv_attr_store) from [] (sysfs_kf_write+0x48/0x54)

• [00.608341] r5:d4d99200 r4:c0792798

• [00.608343] [] (sysfs_kf_write) from [] (kernfs_fop_write+0xec/0x20c)

• [00.608357] r5:d4d99200 r4:0000000c

• [00.608360] [] (kernfs_fop_write) from [] (__vfs_write+0x48/0x1d0)

• [00.608379] r10:0000000c r9:0000000c r8:00000000 r7:d534bf58 r6:c04a9700 r5:d5cdd540

• [00.608383] r4:c1205008

• [00.608385] [] (__vfs_write) from [] (vfs_write+0xb4/0x1d0)

• [00.608400] r10:0000000c r9:0115d118 r8:00000000 r7:d534bf58 r6:0115d118 r5:d5cdd540

• [00.608404] r4:0000000c

• [00.608406] [] (vfs_write) from [] (ksys_write+0x68/0xe0)

• [00.608420] r8:d5cdd540 r7:00000000 r6:00000000 r5:d5cdd540 r4:c1205008

• [00.608423] [] (ksys_write) from [] (sys_write+0x18/0x1c)

• [00.608437] r10:00000004 r9:d534a000 r8:c02011c4 r7:00000004 r6:b6f31d90 r5:0115d118

• [00.608441] r4:0000000c

• [00.608444] [] (sys_write) from [] (ret_fast_syscall+0x0/0x28)

• [00.608456] Exception stack(0xd534bfa8 to 0xd534bff0)

• [00.608464] bfa0: 0000000c 0115d118 00000001 0115d118 0000000c 00000000

• [00.608472] bfc0: 0000000c 0115d118 b6f31d90 00000004 0115d118 0000000c 001042a8 00000000

• [00.608478] bfe0: 0000006c be8c8f08 b6e507b8 b6eac944

• [00.608488] Code: ebedee61 e590303c e3530000 0afffff5 (e7f001f2)

• [00.608496] ---[ end trace 3bf3762de396e28c ]---