[linux-sunxi] Re: [PATCH] pinctrl: use non-devm kmalloc versions for free functions

? 2017?5?11? GMT+08:00 ??10:01:54, Linus Walleij [off-list ref] ??:

On Thu, May 4, 2017 at 1:57 AM, Andre Przywara [off-list ref]
wrote:

quoted

When a pinctrl driver gets interrupted during its probe process
(returning -EPROBE_DEFER), the devres system cleans up all allocated
resources. During this process it calls

pinmux_generic_free_functions()

quoted

and pinctrl_generic_free_groups(), which in turn use managed kmalloc
calls for temporarily allocating some memory. Now those calls seem to
get added to the devres list, but are apparently not covered by the
cleanup process, because this is actually just running and iterating

the

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existing list. This leads to those mallocs being left with the

device,

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which the devres manager complains about when the driver eventually

gets

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probed again:
[    0.825239] ------------[ cut here ]------------
[    0.825256] WARNING: CPU: 1 PID: 89 at drivers/base/dd.c:349

driver_probe_device+0x2ac/0x2e8

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[    0.825258] Modules linked in:
[    0.825262]
[    0.825270] CPU: 1 PID: 89 Comm: kworker/1:1 Not tainted 4.11.0

#307

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[    0.825272] Hardware name: Pine64+ (DT)
[    0.825283] Workqueue: events deferred_probe_work_func
[    0.825288] task: ffff80007c19c100 task.stack: ffff80007c16c000
[    0.825292] PC is at driver_probe_device+0x2ac/0x2e8
[    0.825296] LR is at driver_probe_device+0x108/0x2e8
[    0.825300] pc : [<ffff000008559234>] lr : [<ffff000008559090>]

pstate: 20000045

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....
This warning is triggered because the devres list is not empty. In

this

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case the allocations were using 0 bytes, so no real leaks, but still

this

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ugly warning.
Looking more closely at these *cleanup* functions, devm_kzalloc() is

actually

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not needed, because the memory is just allocated temporarily and can

be

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freed just before returning from this function.
So fix this issue by using the bog standard kcalloc() call instead of
devm_kzalloc() and kfree()ing the memory at the end.

This fixes above warnings on boot, which can be observed on *some*

builds

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for the Pine64, where the pinctrl driver gets loaded early, but it

missing

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resources, so gets deferred and is loaded again (successfully) later.
kernelci caught this as well [1].

Signed-off-by: Andre Przywara <andre.przywara@arm.com>

[1]

https://storage.kernelci.org/net-next/master/v4.11-rc8-2122-gc08bac03d289/arm64/defconfig/lab-baylibre-seattle/boot-sun50i-a64-pine64-plus.html

quoted

---
Hi,

not sure this is the right fix, I am open to suggestions.

I have queued this as a tentative v4.12-rc1 fix, but a bit undertain.

I think 4.11 has also this issue.

Tejun, do I read your comments on the patch as an ACK?

Yours,
Linus Walleij