Messages in this thread | | | Subject | Re: [PATCH] ARM: 9220/1: amba: Add sanity check for dev->periphid in amba_probe() | From | "Leizhen (ThunderTown)" <> | Date | Tue, 30 Aug 2022 10:12:47 +0800 |
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On 2022/8/30 5:17, Saravana Kannan wrote: > On Sat, Aug 27, 2022 at 3:21 AM Zhen Lei <thunder.leizhen@huawei.com> wrote: >> >> Commit f2d3b9a46e0e ("ARM: 9220/1: amba: Remove deferred device addition") >> forcibly invokes device_add() even if dev->periphid is not ready. Although >> it will be remedied in amba_match(): dev->periphid will be initialized >> if everything is in place; Otherwise, return -EPROBE_DEFER to block >> __driver_attach() from further execution. But not all drivers have .match >> hook, such as pl031, the dev->bus->probe will be called directly in >> __driver_attach(). Unfortunately, if dev->periphid is still not >> initialized, the following exception will be triggered. >> >> 8<--- cut here --- >> Unable to handle kernel NULL pointer dereference at virtual address 00000008 >> [00000008] *pgd=00000000 >> Internal error: Oops: 5 [#1] SMP ARM >> Modules linked in: >> CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.0.0-rc2+ #7 >> Hardware name: ARM-Versatile Express >> PC is at pl031_probe+0x8/0x208 >> LR is at amba_probe+0xf0/0x160 >> pc : 80698df8 lr : 8050eb54 psr: 80000013 >> sp : c0825df8 ip : 00000000 fp : 811fda38 >> r10: 00000000 r9 : 80d72470 r8 : fffffdfb >> r7 : 811fd800 r6 : be7eb330 r5 : 00000000 r4 : 811fd900 >> r3 : 80698df0 r2 : 37000000 r1 : 00000000 r0 : 811fd800 >> Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none >> Control: 10c5387d Table: 6000406a DAC: 00000051 >> ... ... >> pl031_probe from amba_probe+0xf0/0x160 >> amba_probe from really_probe+0x118/0x290 >> really_probe from __driver_probe_device+0x84/0xe4 >> __driver_probe_device from driver_probe_device+0x30/0xd0 >> driver_probe_device from __driver_attach+0x8c/0xfc >> __driver_attach from bus_for_each_dev+0x70/0xb0 >> bus_for_each_dev from bus_add_driver+0x168/0x1f4 >> bus_add_driver from driver_register+0x7c/0x118 >> driver_register from do_one_initcall+0x44/0x1ec >> do_one_initcall from kernel_init_freeable+0x238/0x288 >> kernel_init_freeable from kernel_init+0x18/0x12c >> kernel_init from ret_from_fork+0x14/0x2c >> ... ... >> ---[ end trace 0000000000000000 ]--- >> >> Therefore, take the same action as in amba_match(): return -EPROBE_DEFER >> if dev->periphid is not ready in amba_probe(). >> >> Fixes: f2d3b9a46e0e ("ARM: 9220/1: amba: Remove deferred device addition") >> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> >> --- >> KernelVersion: v6.0-rc2 >> drivers/amba/bus.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c >> index 32b0e0b930c1068..2e5572f60692a33 100644 >> --- a/drivers/amba/bus.c >> +++ b/drivers/amba/bus.c >> @@ -274,9 +274,17 @@ static int amba_probe(struct device *dev) >> { >> struct amba_device *pcdev = to_amba_device(dev); >> struct amba_driver *pcdrv = to_amba_driver(dev->driver); >> - const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev); >> + const struct amba_id *id; >> int ret; >> >> + if (!pcdev->periphid) { >> + ret = amba_read_periphid(pcdev); >> + if (ret) >> + return -EPROBE_DEFER; >> + } >> + >> + id = amba_lookup(pcdrv->id_table, pcdev); >> + >> do { >> ret = of_amba_device_decode_irq(pcdev); >> if (ret) > > Cc: Isaac > > Hi Zhen, > > Thanks for the report and trying to fix it. I think your change is in > the right direction but there are a couple of issues that need to be > addressed. > > Firstly, please make your change on top of [1] that fixes a race in my > patch. So, you'll need to use some locks here. Also, you'll need to do > the uevent update thing I do in amba_match() when you read the > periphid successfully for the first time.
OK, I will do it in v2. It seems necessary to add a helper function to avoid duplication of code.
> > Thanks, > Saravana > > [1] - https://lore.kernel.org/lkml/20220818172852.3548-1-isaacmanjarres@google.com/ > . >
-- Regards, Zhen Lei
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