21.02.2022 15:06, Mikko Perttunen пишет:
> On 2/19/22 20:35, Dmitry Osipenko wrote:
>> 18.02.2022 14:39, Mikko Perttunen пишет:
>>> + if (context->memory_context &&
>>> context->client->ops->get_streamid_offset) {
>> ^^^
>>> + int offset =
>>> context->client->ops->get_streamid_offset(context->client);
>>> +
>>> + if (offset >= 0) {
>>> + job->context = context->memory_context;
>>> + job->engine_streamid_offset = offset;
>>> + host1x_context_get(job->context);
>>> + }
>>
>> You should bump refcount unconditionally or you'll get refcnt underflow
>> on put, when offset < 0.
>
> This refcount is intended to be dropped from 'release_job', where it's
> dropped if job->context is set, which it is from this path.
>
>>
>>> + }
>>> +
>>> /*
>>> * job_data is now part of job reference counting, so don't
>>> release
>>> * it from here.
>>> diff --git a/drivers/gpu/drm/tegra/uapi.c b/drivers/gpu/drm/tegra/uapi.c
>>> index 9ab9179d2026..be33da54d12c 100644
>>> --- a/drivers/gpu/drm/tegra/uapi.c
>>> +++ b/drivers/gpu/drm/tegra/uapi.c
>>> @@ -33,6 +33,9 @@ static void tegra_drm_channel_context_close(struct
>>> tegra_drm_context *context)
>>> struct tegra_drm_mapping *mapping;
>>> unsigned long id;
>>> + if (context->memory_context)
>>> + host1x_context_put(context->memory_context);
>>
>> The "if (context->memory_context &&
>> context->client->ops->get_streamid_offset)" above doesn't match the "if
>> (context->memory_context)". You'll get refcount underflow.
>
> And this drop is for the refcount implicitly added when allocating the
> memory context through host1x_context_alloc; so these two places should
> be independent.
>
> Please elaborate if I missed something.
You named context as memory_context and then have
context=context->memory_context. Please try to improve the variable
names, like drm_ctx->host1x_ctx for example.
I'm also not a big fan of the "if (ref) put(ref)" pattern. Won't be
better to move all the "if (!NULL)" checks inside of get()/put() and
make the invocations unconditional?
