Messages in this thread | | | Date | Mon, 21 Feb 2022 14:06:43 +0200 | Subject | Re: [PATCH v3 9/9] drm/tegra: Support context isolation | From | Mikko Perttunen <> |
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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.
Thanks, Mikko
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