linux-kernel - Re: [PATCH 2/5] android: binder: Add allocator selftest

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Date:   Sun, 10 Sep 2017 18:25:52 -0400
From:   Sherry Yang <sherryy@...roid.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Todd Kjos <tkjos@...gle.com>, Martijn Coenen <maco@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arve Hjønnevåg <arve@...roid.com>,
        Riley Andrews <riandrews@...roid.com>,
        "open list:ANDROID DRIVERS" <devel@...verdev.osuosl.org>
Subject: Re: [PATCH 2/5] android: binder: Add allocator selftest

Hi Geert,

This selftest can't run until userspace has called mmap. Since it is
hooked into ioctl, it's probably not worth the effort of making it a
module, since ioctl will have to check at runtime whether the selftest
module has been loaded, which would add overhead even when the test is
not enabled.

Thanks,
Sherry

On Sun, Sep 10, 2017 at 7:48 AM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> Hi Sherry,
>
> On Wed, Aug 16, 2017 at 2:25 AM, Sherry Yang <sherryy@...roid.com> wrote:
>> binder_alloc_selftest tests that alloc_new_buf handles page allocation and
>> deallocation properly when allocate and free buffers. The test allocates 5
>> buffers of various sizes to cover all possible page alignment cases, and
>> frees the buffers using a list of exhaustive freeing order.
>>
>> Test: boot the device with ANDROID_BINDER_IPC_SELFTEST config option
>> enabled. Allocator selftest passes.
>>
>> Change-Id: I9064f60c85b1e0389c88e927e2b147ec92cae0d1
>> Signed-off-by: Sherry Yang <sherryy@...roid.com>
>> ---
>>  drivers/android/Kconfig                 |  10 ++
>>  drivers/android/Makefile                |   1 +
>>  drivers/android/binder.c                |   2 +
>>  drivers/android/binder_alloc.h          |   5 +
>>  drivers/android/binder_alloc_selftest.c | 271 ++++++++++++++++++++++++++++++++
>>  5 files changed, 289 insertions(+)
>>  create mode 100644 drivers/android/binder_alloc_selftest.c
>>
>> diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
>> index 832e885349b1..0f295704abd4 100644
>> --- a/drivers/android/Kconfig
>> +++ b/drivers/android/Kconfig
>> @@ -44,6 +44,16 @@ config ANDROID_BINDER_IPC_32BIT
>>
>>           Note that enabling this will break newer Android user-space.
>>
>> +config ANDROID_BINDER_IPC_SELFTEST
>> +       bool "Android Binder IPC Driver Selftest"
>
> What about making this tristate...
>
>> +       depends on ANDROID_BINDER_IPC
>> +       ---help---
>> +         This feature allows binder selftest to run.
>> +
>> +         Binder selftest checks the allocation and free of binder buffers
>> +         exhaustively with combinations of various buffer sizes and
>> +         alignments.
>> +
>>  endif # if ANDROID
>>
>>  endmenu
>> diff --git a/drivers/android/Makefile b/drivers/android/Makefile
>> index 4b7c726bb560..a01254c43ee3 100644
>> --- a/drivers/android/Makefile
>> +++ b/drivers/android/Makefile
>> @@ -1,3 +1,4 @@
>>  ccflags-y += -I$(src)                  # needed for trace events
>>
>>  obj-$(CONFIG_ANDROID_BINDER_IPC)       += binder.o binder_alloc.o
>> +obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o
>> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
>> index 9f95d7093f32..b31e64c6f666 100644
>> --- a/drivers/android/binder.c
>> +++ b/drivers/android/binder.c
>> @@ -4225,6 +4225,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>         /*pr_info("binder_ioctl: %d:%d %x %lx\n",
>>                         proc->pid, current->pid, cmd, arg);*/
>>
>> +       binder_selftest_alloc(&proc->alloc);
>
> ... and calling the selftest function from module_init() in
> drivers/android/binder_alloc_selftest.c?
>
> That way the test can either run builtin during starup, or during module load,
> like most other selftests?
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds