Re: [igt-dev] [PATCH i-g-t] tests/kms_big_fb: Add assert for drm_intel_bufmgr and intel_batchbuffer before usage

["Sharma, Swati2" <swati2.sharma@intel.com>]

On 04-Sep-19 3:05 PM, Petri Latvala wrote:
> On Wed, Sep 04, 2019 at 01:40:36AM +0530, Sharma, Swati2 wrote:
>> On 13-Aug-19 4:08 PM, Chris Wilson wrote:
>>> Quoting Ser, Simon (2019-08-13 11:28:54)
>>>> On Thu, 2019-08-08 at 18:04 +0530, Swati Sharma wrote:
>>>>> if drm_intel_bufmgr_gem_init() or intel_batchbuffer_alloc()
>>>>> returns NULL, it leads to seg fault as below:
>>>>>
>>>>> root@testrunner:/home/testrunner/swati/otc_gen_graphics-intel-gpu-tools#
>>>>> ./tests/kms_big_fb
>>>>> IGT-Version: 1.24-g976db91 (x86_64) (Linux: 5.1.0-rc6+ x86_64)
>>>>> Max driver framebuffer size 8192x8192
>>>>> RAM: 2749 MiB, GPU address space: 134217728 MiB, GGTT mappable size: 256
>>>>> MiB
>>>>> Received signal SIGSEGV.
>>>>> Stack trace:
>>>>>    #0 [fatal_sig_handler+0x77]
>>>>>    #1 [killpg+0x40]
>>>>>    #2 [drm_intel_bo_alloc+0x0]
>>>>>    #3 [intel_batchbuffer_reset+0x33]
>>>>>    #4 [intel_batchbuffer_alloc+0x34]
>>>>>    #5 [__real_main603+0x3e9]
>>>>>    #6 [main+0x23]
>>>>>    #7 [__libc_start_main+0xf0]
>>>>>    #8 [_start+0x29]
>>>>>    #9 [<unknown>+0x29]
>>>>> Segmentation fault (core dumped)
>>>>>
>>>>> To prevent this igt_assert() is added for both the functions.
>>>> I'm not sure I understand why this segfault happens. Seems like
>>>> drm_intel_bufmgr_gem_init can return NULL in the following cases:
>>>>
>>>> * No compiled with libdrm_intel support, in which case the tests should
>>>>     be skipped
>>>> * Allocation failure or pthread mutex failure, which are unlikely to
>>>>     happen (but it would be nice to log something when those fail)
>>>> * DRM_IOCTL_I915_GEM_APERTURE fails (but something is printed to
>>>>     stderr, it doesn't seem like this is the case here)
>>>>
>>>> Am I missing something?
>>> Usual cause is unrecognised GPU by libdrm. In which case it should be an
>>> igt_require_f(data.bufmgr, "Update libdrm for %s support\n", intel_chipset_get_name(devid))
>>> Roll that up into an <somename>_wrapper and spread far and wide.
>>> (Although I prefer the option of not using libdrm_intel in the first
>>> place.)
>>> -Chris
>> Shouldn't we add igt_assert() and instead add wrapper func to check bufmgr?
> 
> That would lead to fails. The thumb rule is that fails happen from
> kernel bugs, skips happen from untestable configurations (hardware &
> software). igt_require is more suitable for this.
> 
> 
I have one query, why there isn't the generic rule for this. For IGTs
such as gem_write_read_ring_switch, gem_unref_active_buffers, etc we 
have igt_assert() whereas you will find few IGTs like 
gem_unfence_active_buffers, gem_tiled_partial_pwrite_pread, etc which 
doesn't even have igt_assert(). What should be done?

-- 
~Swati Sharma
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