Quoting Sagar Arun Kamble (2018-01-24 04:09:09)
> diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
> index 8f2da30..35de889 100644
> --- a/drivers/gpu/drm/i915/intel_guc_log.c
> +++ b/drivers/gpu/drm/i915/intel_guc_log.c
> @@ -153,6 +153,8 @@ static int guc_log_relay_file_create(struct intel_guc *guc)
> if (!i915_modparams.guc_log_level)
> return 0;
>
> + mutex_lock(&guc->log.runtime.relay_lock);
> +
> /* For now create the log file in /sys/kernel/debug/dri/0 dir */
> log_dir = dev_priv->drm.primary->debugfs_root;
>
> @@ -169,16 +171,26 @@ static int guc_log_relay_file_create(struct intel_guc *guc)
> */
> if (!log_dir) {
> DRM_ERROR("Debugfs dir not available yet for GuC log file\n");
> - return -ENODEV;
> + ret = -ENODEV;
> + goto out_unlock;
> }
>
> ret = relay_late_setup_files(guc->log.runtime.relay_chan, "guc_log", log_dir);
> if (ret < 0 && ret != -EEXIST) {
> DRM_ERROR("Couldn't associate relay chan with file %d\n", ret);
> - return ret;
> + goto out_unlock;
> }
>
> - return 0;
> +out_unlock:
> + mutex_unlock(&guc->log.runtime.relay_lock);
> + return ret;
> +}
> +
> +static bool guc_log_has_relay(struct intel_guc *guc)
> +{
> + lockdep_assert_held(&guc->log.runtime.relay_lock);
> +
> + return guc->log.runtime.relay_chan != NULL;
> }
>
> static void guc_move_to_next_buf(struct intel_guc *guc)
> @@ -188,6 +200,9 @@ static void guc_move_to_next_buf(struct intel_guc *guc)
> */
> smp_wmb();
>
> + if (!guc_log_has_relay(guc))
> + return;
> +
> /* All data has been written, so now move the offset of sub buffer. */
> relay_reserve(guc->log.runtime.relay_chan, guc->log.vma->obj->base.size);
>
> @@ -197,7 +212,7 @@ static void guc_move_to_next_buf(struct intel_guc *guc)
>
> static void *guc_get_write_buffer(struct intel_guc *guc)
> {
> - if (!guc->log.runtime.relay_chan)
> + if (!guc_log_has_relay(guc))
> return NULL;
>
> /* Just get the base address of a new sub buffer and copy data into it
> @@ -265,6 +280,8 @@ static void guc_read_update_log_buffer(struct intel_guc *guc)
> /* Get the pointer to shared GuC log buffer */
> log_buf_state = src_data = guc->log.runtime.buf_addr;
>
> + mutex_lock(&guc->log.runtime.relay_lock);
> +
> /* Get the pointer to local buffer to store the logs */
> log_buf_snapshot_state = dst_data = guc_get_write_buffer(guc);
Hmm. The locking here tells me that we are being careful in case the
relay_chan disappears, but we don't handle the NULL pointer here.
> @@ -344,6 +361,8 @@ static void guc_read_update_log_buffer(struct intel_guc *guc)
> DRM_ERROR_RATELIMITED("no sub-buffer to capture logs\n");
> guc->log.capture_miss_count++;
> }
> +
> + mutex_unlock(&guc->log.runtime.relay_lock);
> }
>
> static void capture_logs_work(struct work_struct *work)
> @@ -363,8 +382,6 @@ static int guc_log_runtime_create(struct intel_guc *guc)
> {
> struct drm_i915_private *dev_priv = guc_to_i915(guc);
> void *vaddr;
> - struct rchan *guc_log_relay_chan;
> - size_t n_subbufs, subbuf_size;
> int ret;
>
> lockdep_assert_held(&dev_priv->drm.struct_mutex);
> @@ -387,8 +404,44 @@ static int guc_log_runtime_create(struct intel_guc *guc)
>
> guc->log.runtime.buf_addr = vaddr;
>
> + return 0;
> +}
> +
> +static void guc_log_runtime_destroy(struct intel_guc *guc)
> +{
> + /*
> + * It's possible that the runtime stuff was never allocated because
> + * GuC log was disabled at the boot time.
> + **/
> + if (!guc_log_has_runtime(guc))
> + return;
> +
> + i915_gem_object_unpin_map(guc->log.vma->obj);
> + guc->log.runtime.buf_addr = NULL;
> +}
> +
> +void intel_guc_log_init_early(struct intel_guc *guc)
> +{
> + mutex_init(&guc->log.runtime.relay_lock);
> + INIT_WORK(&guc->log.runtime.flush_work, capture_logs_work);
> +}
> +
> +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;
> +
> + mutex_lock(&guc->log.runtime.relay_lock);
> +
> + 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 +460,39 @@ 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);
> + mutex_unlock(&guc->log.runtime.relay_lock);
> +
> return 0;
>
> -err_vaddr:
> - i915_gem_object_unpin_map(guc->log.vma->obj);
> - guc->log.runtime.buf_addr = NULL;
> +err:
> + mutex_unlock(&guc->log.runtime.relay_lock);
> + /* 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)
> {
> + mutex_lock(&guc->log.runtime.relay_lock);
> +
> /*
> - * It's possible that the runtime stuff was never allocated because
> + * It's possible that the relay was never allocated because
> * GuC log was disabled at the boot time.
> */
> - if (!guc_log_has_runtime(guc))
> - return;
> + if (!guc_log_has_relay(guc))
> + goto out_unlock;
>
> relay_close(guc->log.runtime.relay_chan);
> - i915_gem_object_unpin_map(guc->log.vma->obj);
> - guc->log.runtime.buf_addr = NULL;
> + guc->log.runtime.relay_chan = NULL;
> +
> +out_unlock:
> + mutex_unlock(&guc->log.runtime.relay_lock);
> }
>
> static int guc_log_late_setup(struct intel_guc *guc)
> @@ -441,17 +500,24 @@ static int guc_log_late_setup(struct intel_guc *guc)
> struct drm_i915_private *dev_priv = guc_to_i915(guc);
> int ret;
>
> - lockdep_assert_held(&dev_priv->drm.struct_mutex);
> -
> if (!guc_log_has_runtime(guc)) {
> /*
> * If log was disabled at boot time, then setup needed to handle
> * log buffer flush interrupts would not have been done yet, so
> * do that now.
> */
> - ret = guc_log_runtime_create(guc);
> + ret = intel_guc_log_relay_create(guc);
> if (ret)
> goto err;
> +
> + mutex_lock(&dev_priv->drm.struct_mutex);
> + intel_runtime_pm_get(dev_priv);
> + ret = guc_log_runtime_create(guc);
> + intel_runtime_pm_put(dev_priv);
> + mutex_unlock(&dev_priv->drm.struct_mutex);
> +
> + if (ret)
> + goto err_relay;
> }
>
> ret = guc_log_relay_file_create(guc);
> @@ -461,7 +527,11 @@ static int guc_log_late_setup(struct intel_guc *guc)
> return 0;
>
> err_runtime:
> + mutex_lock(&dev_priv->drm.struct_mutex);
> guc_log_runtime_destroy(guc);
> + mutex_unlock(&dev_priv->drm.struct_mutex);
> +err_relay:
> + intel_guc_log_relay_destroy(guc);
> err:
> /* logging will remain off */
> i915_modparams.guc_log_level = 0;
> @@ -490,7 +560,11 @@ static void guc_flush_logs(struct intel_guc *guc)
> return;
>
> /* First disable the interrupts, will be renabled afterwards */
> + mutex_lock(&dev_priv->drm.struct_mutex);
> + intel_runtime_pm_get(dev_priv);
> gen9_disable_guc_interrupts(dev_priv);
> + intel_runtime_pm_put(dev_priv);
> + mutex_unlock(&dev_priv->drm.struct_mutex);
>
> /* Before initiating the forceful flush, wait for any pending/ongoing
> * flush to complete otherwise forceful flush may not actually happen.
> @@ -498,7 +572,9 @@ static void guc_flush_logs(struct intel_guc *guc)
> flush_work(&guc->log.runtime.flush_work);
>
> /* Ask GuC to update the log buffer state */
> + intel_runtime_pm_get(dev_priv);
> guc_log_flush(guc);
> + intel_runtime_pm_put(dev_priv);
>
> /* GuC would have updated log buffer by now, so capture it */
> guc_log_capture_logs(guc);
> @@ -509,17 +585,10 @@ int intel_guc_log_create(struct intel_guc *guc)
> struct i915_vma *vma;
> unsigned long offset;
> u32 flags;
> - u32 size;
> int ret;
>
> GEM_BUG_ON(guc->log.vma);
>
> - /* The first page is to save log buffer state. Allocate one
> - * extra page for others in case for overlap */
> - size = (1 + GUC_LOG_DPC_PAGES + 1 +
> - GUC_LOG_ISR_PAGES + 1 +
> - GUC_LOG_CRASH_PAGES + 1) << PAGE_SHIFT;
> -
> /* We require SSE 4.1 for fast reads from the GuC log buffer and
> * it should be present on the chipsets supporting GuC based
> * submisssions.
> @@ -529,7 +598,7 @@ int intel_guc_log_create(struct intel_guc *guc)
> goto err;
> }
>
> - vma = intel_guc_allocate_vma(guc, size);
> + vma = intel_guc_allocate_vma(guc, GUC_LOG_SIZE);
> if (IS_ERR(vma)) {
> ret = PTR_ERR(vma);
> goto err;
> @@ -584,7 +653,15 @@ int i915_guc_log_control(struct drm_i915_private *dev_priv, u64 control_val)
> return 0;
>
> verbosity = enable_logging ? control_val - 1 : 0;
> +
> + ret = mutex_lock_interruptible(&dev_priv->drm.struct_mutex);
> + if (ret)
> + return ret;
> + intel_runtime_pm_get(dev_priv);
> ret = guc_log_control(guc, enable_logging, verbosity);
> + intel_runtime_pm_put(dev_priv);
> + mutex_unlock(&dev_priv->drm.struct_mutex);
> +
> if (ret < 0) {
> DRM_DEBUG_DRIVER("guc_logging_control action failed %d\n", ret);
> return ret;
> @@ -605,7 +682,11 @@ int i915_guc_log_control(struct drm_i915_private *dev_priv, u64 control_val)
> }
>
> /* GuC logging is currently the only user of Guc2Host interrupts */
> + mutex_lock(&dev_priv->drm.struct_mutex);
> + intel_runtime_pm_get(dev_priv);
> gen9_enable_guc_interrupts(dev_priv);
> + intel_runtime_pm_put(dev_priv);
> + mutex_unlock(&dev_priv->drm.struct_mutex);
> } else {
> /*
> * Once logging is disabled, GuC won't generate logs & send an
> @@ -627,13 +708,13 @@ void i915_guc_log_register(struct drm_i915_private *dev_priv)
> if (!USES_GUC_SUBMISSION(dev_priv) || !i915_modparams.guc_log_level)
> return;
>
> - mutex_lock(&dev_priv->drm.struct_mutex);
> guc_log_late_setup(&dev_priv->guc);
> - mutex_unlock(&dev_priv->drm.struct_mutex);
> }
>
> void i915_guc_log_unregister(struct drm_i915_private *dev_priv)
> {
> + struct intel_guc *guc = &dev_priv->guc;
> +
> if (!USES_GUC_SUBMISSION(dev_priv))
> return;
>
> @@ -643,6 +724,8 @@ void i915_guc_log_unregister(struct drm_i915_private *dev_priv)
> gen9_disable_guc_interrupts(dev_priv);
> intel_runtime_pm_put(dev_priv);
>
> - guc_log_runtime_destroy(&dev_priv->guc);
> + guc_log_runtime_destroy(guc);
> mutex_unlock(&dev_priv->drm.struct_mutex);
> +
> + intel_guc_log_relay_destroy(guc);
> }
This looks all reasonably well described by the addition of the
relay_lock and the interactions look fine. The only mistake I could see,
in the story told by this patch, was the runtime checking.
-Chris
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