On Tue, 21 Sep 2021 05:16:35 +0100, Daniel Palmer <daniel@xxxxxxxx> wrote: + Linus. > So if I set irq_chip_ack_parent as the ack callback I get another explosion: > > # gpiomon -r 0 44 > [ 22.370689] 8<--- cut here --- > [ 22.373802] Unable to handle kernel NULL pointer dereference at > virtual address 00000018 > [ 22.381945] pgd = (ptrval) > [ 22.384685] [00000018] *pgd=235cb835, *pte=00000000, *ppte=00000000 > [ 22.391038] Internal error: Oops: 17 [#1] SMP ARM > [ 22.395776] Modules linked in: > [ 22.398860] CPU: 1 PID: 193 Comm: gpiomon Not tainted 5.15.0-rc2+ #2566 > [ 22.405515] Hardware name: MStar/Sigmastar Armv7 (Device Tree) > [ 22.411376] PC is at irq_chip_ack_parent+0x8/0x10 > [ 22.416120] LR is at __irq_do_set_handler+0x3c/0x11c > [ 22.421119] pc : [<c017f498>] lr : [<c018029c>] psr: a0040093 > [ 22.427419] sp : c3505d68 ip : ffffe000 fp : 00000000 > [ 22.432673] r10: c0d592d4 r9 : 00000001 r8 : 00000000 > [ 22.437927] r7 : c3502618 r6 : 00000000 r5 : c017b9cc r4 : c3502600 > [ 22.444489] r3 : 00000000 r2 : c10bb294 r1 : c10bb294 r0 : c26a3440 > [ 22.451053] Flags: NzCv IRQs off FIQs on Mode SVC_32 ISA ARM > Segment user > [ 22.458317] Control: 10c5387d Table: 235b006a DAC: 00000055 > ---snip--- > [ 22.725196] [<c017f498>] (irq_chip_ack_parent) from [<c018029c>] > (__irq_do_set_handler+0x3c/0x11c) > [ 22.734219] [<c018029c>] (__irq_do_set_handler) from [<c01803b4>] > (__irq_set_handler+0x38/0x50) > [ 22.742976] [<c01803b4>] (__irq_set_handler) from [<c0181880>] > (irq_domain_set_info+0x34/0x48) > [ 22.751649] [<c0181880>] (irq_domain_set_info) from [<c046f838>] > (gpiochip_hierarchy_irq_domain_alloc+0x104/0x228) > [ 22.762069] [<c046f838>] (gpiochip_hierarchy_irq_domain_alloc) from > [<c0182c38>] (__irq_domain_alloc_irqs+0xd8/0x318) > [ 22.772748] [<c0182c38>] (__irq_domain_alloc_irqs) from > [<c01832e8>] (irq_create_fwspec_mapping+0x22c/0x298) > [ 22.782641] [<c01832e8>] (irq_create_fwspec_mapping) from > [<c0470124>] (gpiochip_to_irq+0x60/0x84) > [ 22.791664] [<c0470124>] (gpiochip_to_irq) from [<c046ef18>] > (gpiod_to_irq+0x48/0x60) > [ 22.799552] [<c046ef18>] (gpiod_to_irq) from [<c0477a48>] > (gpio_ioctl+0x1b4/0x420) > [ 22.807178] [<c0477a48>] (gpio_ioctl) from [<c0262e4c>] (vfs_ioctl+0x20/0x38) > [ 22.814371] [<c0262e4c>] (vfs_ioctl) from [<c0263708>] (sys_ioctl+0xb0/0x818) > [ 22.821564] [<c0263708>] (sys_ioctl) from [<c0100060>] > (ret_fast_syscall+0x0/0x1c) > [ 22.829190] Exception stack(0xc3505fa8 to 0xc3505ff0) > [ 22.834273] 5fa0: ???????? ???????? ???????? > ???????? ???????? ???????? > [ 22.842488] 5fc0: ???????? ???????? ???????? ???????? ???????? > ???????? ???????? ???????? > [ 22.850701] 5fe0: ???????? ???????? ???????? ???????? > [ 22.855790] Code: e593301c e12fff13 e5900018 e5903010 (e5933018) > [ 22.861919] ---[ end trace 10524aa06eced7e3 ]--- This seems to be caused by your GPIO driver installing a flow handler (via irq_domain_set_info()), which is a bit odd. I would expect that only the root irqchip in the hierarchy would do that. At the point where this is called, the hierarchy isn't fully populated (the irq_domain_alloc_irqs_parent() call comes after that), and irq_chip_ack_parent() explodes as above. Linus: is there a reason why the gpiolib insist on setting its own handler while building the hierarchy? I guess this could be worked around by swapping the calls to irq_domain_set_info and irq_domain_alloc_irqs_parent, but having two levels of the hierarchy competing for the flow handler looks a bit odd. Thanks, M. -- Without deviation from the norm, progress is not possible.
