Re: [PATCH 3/3] drm/amdgpu: Use delayed work to collect RAS error counters

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 26.05.21 um 02:40 schrieb Luben Tuikov:
> On Context Query2 IOCTL return the correctable and
> uncorrectable errors in O(1) fashion, from cached
> values, and schedule a delayed work function to
> calculate and cache them for the next such IOCTL.
>
> v2: Cancel pending delayed work at ras_fini().
>
> Cc: Alexander Deucher <Alexander.Deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: John Clements <john.clements@amd.com>
> Cc: Hawking Zhang <Hawking.Zhang@amd.com>
> Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 32 +++++++++++++++++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 41 +++++++++++++++++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h |  5 +++
>   3 files changed, 76 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index bb0cfe871aba..4e95d255960b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -331,10 +331,13 @@ static int amdgpu_ctx_query(struct amdgpu_device *adev,
>   	return 0;
>   }
>   
> +#define AMDGPU_RAS_COUNTE_DELAY_MS 3000
> +
>   static int amdgpu_ctx_query2(struct amdgpu_device *adev,
> -	struct amdgpu_fpriv *fpriv, uint32_t id,
> -	union drm_amdgpu_ctx_out *out)
> +			     struct amdgpu_fpriv *fpriv, uint32_t id,
> +			     union drm_amdgpu_ctx_out *out)
>   {
> +	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
>   	struct amdgpu_ctx *ctx;
>   	struct amdgpu_ctx_mgr *mgr;
>   
> @@ -361,6 +364,31 @@ static int amdgpu_ctx_query2(struct amdgpu_device *adev,
>   	if (atomic_read(&ctx->guilty))
>   		out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_GUILTY;
>   
> +	if (adev->ras_enabled && con) {
> +		/* Return the cached values in O(1),
> +		 * and schedule delayed work to cache
> +		 * new vaues.
> +		 */
> +		int ce_count, ue_count;
> +
> +		ce_count = atomic_read(&con->ras_ce_count);
> +		ue_count = atomic_read(&con->ras_ue_count);
> +
> +		if (ce_count != ctx->ras_counter_ce) {
> +			ctx->ras_counter_ce = ce_count;
> +			out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_RAS_CE;
> +		}
> +
> +		if (ue_count != ctx->ras_counter_ue) {
> +			ctx->ras_counter_ue = ue_count;
> +			out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_RAS_UE;
> +		}
> +
> +		if (!delayed_work_pending(&con->ras_counte_delay_work))
> +			schedule_delayed_work(&con->ras_counte_delay_work,
> +				  msecs_to_jiffies(AMDGPU_RAS_COUNTE_DELAY_MS));

You can skip the delayed_work_pending() check here, if I'm not totally 
mistaken that is already integrated in the schedule_delayed_work() logic.

> +	}
> +
>   	mutex_unlock(&mgr->lock);
>   	return 0;
>   }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> index ed3c43e8b0b5..01114529040a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> @@ -27,6 +27,7 @@
>   #include <linux/uaccess.h>
>   #include <linux/reboot.h>
>   #include <linux/syscalls.h>
> +#include <linux/pm_runtime.h>
>   
>   #include "amdgpu.h"
>   #include "amdgpu_ras.h"
> @@ -2116,6 +2117,30 @@ static void amdgpu_ras_check_supported(struct amdgpu_device *adev)
>   		adev->ras_hw_enabled & amdgpu_ras_mask;
>   }
>   
> +static void amdgpu_ras_counte_dw(struct work_struct *work)
> +{
> +	struct amdgpu_ras *con = container_of(work, struct amdgpu_ras,
> +					      ras_counte_delay_work.work);
> +	struct amdgpu_device *adev = con->adev;
> +	struct drm_device *dev = &adev->ddev;
> +	unsigned long ce_count, ue_count;
> +	int res;
> +
> +	res = pm_runtime_get_sync(dev->dev);
> +	if (res < 0)
> +		goto Out;
> +
> +	/* Cache new values.
> +	 */
> +	amdgpu_ras_query_error_count(adev, &ce_count, &ue_count);
> +	atomic_set(&con->ras_ce_count, ce_count);
> +	atomic_set(&con->ras_ue_count, ue_count);
> +
> +	pm_runtime_mark_last_busy(dev->dev);
> +Out:
> +	pm_runtime_put_autosuspend(dev->dev);
> +}
> +
>   int amdgpu_ras_init(struct amdgpu_device *adev)
>   {
>   	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
> @@ -2130,6 +2155,11 @@ int amdgpu_ras_init(struct amdgpu_device *adev)
>   	if (!con)
>   		return -ENOMEM;
>   
> +	con->adev = adev;
> +	INIT_DELAYED_WORK(&con->ras_counte_delay_work, amdgpu_ras_counte_dw);
> +	atomic_set(&con->ras_ce_count, 0);
> +	atomic_set(&con->ras_ue_count, 0);
> +
>   	con->objs = (struct ras_manager *)(con + 1);
>   
>   	amdgpu_ras_set_context(adev, con);
> @@ -2233,6 +2263,8 @@ int amdgpu_ras_late_init(struct amdgpu_device *adev,
>   			 struct ras_fs_if *fs_info,
>   			 struct ras_ih_if *ih_info)
>   {
> +	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
> +	unsigned long ue_count, ce_count;
>   	int r;
>   
>   	/* disable RAS feature per IP block if it is not supported */
> @@ -2273,6 +2305,12 @@ int amdgpu_ras_late_init(struct amdgpu_device *adev,
>   	if (r)
>   		goto sysfs;
>   
> +	/* Those are the cached values at init.
> +	 */
> +	amdgpu_ras_query_error_count(adev, &ce_count, &ue_count);
> +	atomic_set(&con->ras_ce_count, ce_count);
> +	atomic_set(&con->ras_ue_count, ue_count);
> +
>   	return 0;
>   cleanup:
>   	amdgpu_ras_sysfs_remove(adev, ras_block);
> @@ -2390,6 +2428,9 @@ int amdgpu_ras_fini(struct amdgpu_device *adev)
>   	if (con->features)
>   		amdgpu_ras_disable_all_features(adev, 1);
>   
> +	if (delayed_work_pending(&con->ras_counte_delay_work))
> +		cancel_delayed_work_sync(&con->ras_counte_delay_work);
> +

Using delayed_work_pending() here causes a race problem, because the 
work might be running at the moment.

Just calling cancel_delayed_work_sync() should fix that because the 
*_sync() variant also waits for running delayed work items to finish.

Apart from that the patch looks good to me.

Regards,
Christian.

>   	amdgpu_ras_set_context(adev, NULL);
>   	kfree(con);
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
> index 10fca0393106..256cea5d34f2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h
> @@ -340,6 +340,11 @@ struct amdgpu_ras {
>   
>   	/* disable ras error count harvest in recovery */
>   	bool disable_ras_err_cnt_harvest;
> +
> +	/* RAS count errors delayed work */
> +	struct delayed_work ras_counte_delay_work;
> +	atomic_t ras_ue_count;
> +	atomic_t ras_ce_count;
>   };
>   
>   struct ras_fs_data {

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