On 1/22/2018 4:17 PM, Chris Wilson wrote:
Quoting Sagar Arun Kamble (2018-01-22 10:38:10)
On 1/22/2018 3:46 PM, Chris Wilson wrote:
Quoting Sagar Arun Kamble (2018-01-22 08:26:01)
+int intel_guc_log_relay_create(struct intel_guc *guc)
+{
+ struct drm_i915_private *dev_priv = guc_to_i915(guc);
+ struct rchan *guc_log_relay_chan;
+ size_t n_subbufs, subbuf_size;
+ int ret;
+
+ if (!i915_modparams.guc_log_level)
+ return 0;
+
+ GEM_BUG_ON(guc_log_has_relay(guc));
+
/* Keep the size of sub buffers same as shared log buffer */
- subbuf_size = guc->log.vma->obj->base.size;
+ subbuf_size = GUC_LOG_SIZE;
/* Store up to 8 snapshots, which is large enough to buffer sufficient
* boot time logs and provides enough leeway to User, in terms of
@@ -407,33 +442,31 @@ static int guc_log_runtime_create(struct intel_guc *guc)
DRM_ERROR("Couldn't create relay chan for GuC logging\n");
ret = -ENOMEM;
- goto err_vaddr;
+ goto err;
}
GEM_BUG_ON(guc_log_relay_chan->subbuf_size < subbuf_size);
guc->log.runtime.relay_chan = guc_log_relay_chan;
- INIT_WORK(&guc->log.runtime.flush_work, capture_logs_work);
return 0;
-err_vaddr:
- i915_gem_object_unpin_map(guc->log.vma->obj);
- guc->log.runtime.buf_addr = NULL;
+err:
+ /* logging will be off */
+ i915_modparams.guc_log_level = 0;
return ret;
}
-static void guc_log_runtime_destroy(struct intel_guc *guc)
+void intel_guc_log_relay_destroy(struct intel_guc *guc)
{
Now exposed to multiple users, we need to document what the locking
requirements are here. Or add some local locking.
Do you mean locking between relay_create and relay_destroy?
We need a lock around guc->log.runtime.relay_chan as the destroy path is
not ostensibly serialised between multiple potential callers. Ordinarily
I would have said that serialisation for create/destroy/access of
relay_chan was guaranteed by init/fini ordering,
I was also initially thinking that init/fini ordering should take care
of synchronization.
Checked further and I see that relay_open and relay_destroy are
synchronized by relay_channels_mutex
and internally if needed through debugfs inode synchronization. So I
feel we need not add new lock.
but that's no longer
clear (based on a 5min read of the patch).
The most important question is "can relay_destroy be called while some
user still has access to the relay_chan?"
Looks like at the
moment, _create is using struct_mutex,
relay_create and relay_destroy are now to be done outside of struct_mutex.
I will add this documentation to the functions.
(lockdep_assert_held :)
-Chris
--
Thanks,
Sagar
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