Re: [PATCH v3 04/10] lib/igt_drm_netlink: add get_error_counter support

["Koppuravuri, Ravi Kishore" <ravi.kishore.koppuravuri@intel.com>]

On 31-08-2026 14:18, Jani Nikula wrote:
> On Mon, 24 Aug 2026, Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com> wrote:
>> Add netlink request/response handling for DRM_RAS_CMD_GET_ERROR_COUNTER.
>>
>> Signed-off-by: Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com>
>> ---
>> v2:Handled ACK/FINISH/ERR nl responses using separate callbacks
>>     Added a check whether error_value updated by valid callback or not
>>     Added a check whether response required for the command or not
>> ---
>> ---
>>   lib/igt_drm_netlink.c | 264 +++++++++++++++++++++++++++++++++++++++++-
>>   lib/igt_drm_netlink.h |  14 +++
>>   2 files changed, 276 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/igt_drm_netlink.c b/lib/igt_drm_netlink.c
>> index fec1639b4..76223f3de 100644
>> --- a/lib/igt_drm_netlink.c
>> +++ b/lib/igt_drm_netlink.c
>> @@ -5,6 +5,7 @@
>>   
>>   #include <stdbool.h>
>>   #include <stdint.h>
>> +#include <errno.h>
>>   #include <stdio.h>
>>   #include <stdlib.h>
>>   #include <string.h>
>> @@ -17,6 +18,225 @@
>>   #include "igt_core.h"
>>   #include "igt_drm_netlink.h"
>>   
>> +static int ras_command_cb(struct nl_msg *msg, void *arg)
>> +{
>> +	struct app_context *ctx = arg;
>> +	struct nlmsghdr *nlh;
>> +	struct genlmsghdr *gnlh;
>> +	int ret;
>> +
>> +	nlh = nlmsg_hdr(msg);
>> +	gnlh = nlmsg_data(nlh);
>> +
>> +	switch (gnlh->cmd) {
>> +	case DRM_RAS_CMD_GET_ERROR_COUNTER: {
>> +		struct nlattr *attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_MAX + 1];
>> +
>> +		ret = genlmsg_parse(nlh, 0, attrs,
>> +				    DRM_RAS_A_ERROR_COUNTER_ATTRS_MAX, NULL);
>> +		if (ret < 0)
>> +			return NL_SKIP;
>> +
>> +		if (!attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_VALUE])
>> +			return NL_SKIP;
>> +
>> +		ctx->error_value = nla_get_u32(attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_VALUE]);
>> +		break;
>> +	}
>> +	default:
>> +		return NL_SKIP;
>> +	}
>> +
>> +	ctx->reply_received = true;
>> +	if (ctx->ack_received)
>> +		ctx->cmd_done = true;
>> +
>> +	return NL_OK;
>> +}
>> +
>> +static int ras_error_cb(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg)
>> +{
>> +	struct app_context *ctx = arg;
>> +
>> +	ctx->last_nl_error = err->error;
>> +	ctx->cmd_done = true;
>> +
>> +	return NL_STOP;
>> +}
>> +
>> +static int ras_ack_cb(struct nl_msg *msg, void *arg)
>> +{
>> +	struct app_context *ctx = arg;
>> +
>> +	ctx->ack_received = true;
>> +	if (!ctx->response_required || ctx->reply_received)
>> +		ctx->cmd_done = true;
>> +
>> +	return NL_STOP;
>> +}
>> +
>> +static int ras_finish_cb(struct nl_msg *msg, void *arg)
>> +{
>> +	struct app_context *ctx = arg;
>> +
>> +	ctx->cmd_done = true;
>> +
>> +	return NL_STOP;
>> +}
>> +
>> +static int register_callbacks(struct nl_cb *cb, struct app_context *ctx)
>> +{
>> +	int ret;
>> +
>> +	ret = nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, ras_command_cb, ctx);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, ras_ack_cb, ctx);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, ras_finish_cb, ctx);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = nl_cb_err(cb, NL_CB_CUSTOM, ras_error_cb, ctx);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int send_and_recv_nl_msg(struct app_context *ctx,
>> +				struct nl_cb *cb,
>> +				struct nl_msg *msg)
>> +{
>> +	int ret;
>> +
>> +	ret = nl_send_auto(ctx->sock, msg);
>> +	nlmsg_free(msg);
>> +	if (ret < 0) {
>> +		nl_cb_put(cb);
>> +		return ret;
>> +	}
>> +
>> +	/* NL Reply and ACK arrive as separate responses */
>> +	while (!ctx->cmd_done) {
>> +		ret = nl_recvmsgs(ctx->sock, cb);
>> +		if (ret < 0)
>> +			break;
>> +	}
>> +	nl_cb_put(cb);
>> +
>> +	return ret < 0 ? ret : 0;
>> +}
>> +
>> +static int send_command(struct app_context *ctx, uint8_t cmd)
>> +{
>> +	struct nl_cb *cb;
>> +	struct nl_msg *msg;
>> +	void *msg_head;
>> +	int ret;
>> +
>> +	msg = nlmsg_alloc();
>> +	if (!msg)
>> +		return -ENOMEM;
>> +
>> +	ctx->last_nl_error = 0;
>> +	ctx->cmd_done = false;
>> +	ctx->reply_received = false;
>> +	ctx->ack_received = false;
>> +	ctx->response_required = false;
>> +
>> +	msg_head = genlmsg_put(msg,
>> +			       NL_AUTO_PORT,
>> +			       NL_AUTO_SEQ,
>> +			       ctx->family_id,
>> +			       0,
>> +			       NLM_F_REQUEST | NLM_F_ACK,
>> +			       cmd,
>> +			       DRM_RAS_FAMILY_VERSION);
>> +	if (!msg_head) {
>> +		nlmsg_free(msg);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	switch (cmd) {
>> +	case DRM_RAS_CMD_GET_ERROR_COUNTER:
>> +		ctx->response_required = true;
>> +		ret = nla_put_u32(msg,
>> +				  DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID,
>> +				  ctx->node_id);
>> +		if (ret < 0) {
>> +			nlmsg_free(msg);
>> +			return ret;
>> +		}
>> +
>> +		ret = nla_put_u32(msg,
>> +				  DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID,
>> +				  ctx->error_id);
>> +		if (ret < 0) {
>> +			nlmsg_free(msg);
>> +			return ret;
>> +		}
>> +		break;
>> +	default:
>> +		nlmsg_free(msg);
>> +		return -EOPNOTSUPP;
>> +	}
>> +
>> +	cb = nl_cb_alloc(NL_CB_DEFAULT);
>> +	if (!cb) {
>> +		nlmsg_free(msg);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	ret = register_callbacks(cb, ctx);
>> +	if (ret < 0) {
>> +		nl_cb_put(cb);
>> +		nlmsg_free(msg);
>> +		return ret;
>> +	}
>> +
>> +	return send_and_recv_nl_msg(ctx, cb, msg);
>> +}
>> +
>> +static int init_app_context(struct app_context *ctx)
>> +{
>> +	if (!ctx)
>> +		return -EINVAL;
>> +
>> +	ctx->sock = NULL;
>> +	ctx->node_id = UINT32_MAX;
>> +	ctx->error_id = UINT32_MAX;
>> +	ctx->error_value = 0;
>> +	ctx->last_nl_error = 0;
>> +	ctx->cmd_done = false;
>> +	ctx->reply_received = false;
>> +	ctx->ack_received = false;
>> +	ctx->response_required = false;
>> +	ctx->family_id = -1;
>> +
>> +	return 0;
>> +}
>> +
>> +static void cleanup_app_context(struct app_context *ctx)
>> +{
>> +	if (!ctx)
>> +		return;
>> +
>> +	ctx->sock = NULL;
>> +	ctx->node_id = UINT32_MAX;
>> +	ctx->error_id = UINT32_MAX;
>> +	ctx->error_value = 0;
>> +	ctx->last_nl_error = 0;
>> +	ctx->cmd_done = false;
>> +	ctx->reply_received = false;
>> +	ctx->ack_received = false;
>> +	ctx->response_required = false;
>> +	ctx->family_id = -1;
>> +}
>> +
>>   void igt_cleanup_nl_socket(struct app_context *ctx)
>>   {
>>   	if (!ctx || !ctx->sock)
>> @@ -24,14 +244,20 @@ void igt_cleanup_nl_socket(struct app_context *ctx)
>>   
>>   	nl_close(ctx->sock);
>>   	nl_socket_free(ctx->sock);
>> -	ctx->sock = NULL;
>> -	ctx->family_id = -1;
>> +
>> +	cleanup_app_context(ctx);
>>   
>>   	igt_debug("Cleaned up netlink socket.\n");
>>   }
>>   
>>   int igt_init_nl_socket(struct app_context *ctx)
>>   {
>> +	int ret;
>> +
>> +	ret = init_app_context(ctx);
>> +	if (ret < 0)
>> +		return ret;
>> +
>>   	ctx->sock = nl_socket_alloc();
>>   	if (!ctx->sock)
>>   		return -1;
>> @@ -58,3 +284,37 @@ int igt_init_nl_socket(struct app_context *ctx)
>>   		  DRM_RAS_FAMILY_NAME, ctx->family_id);
>>   	return 0;
>>   }
>> +
>> +int igt_get_error_counter(struct app_context *ctx)
>> +{
>> +	int ret;
>> +
>> +	if (!ctx || !ctx->sock || ctx->family_id < 0)
>> +		return -EINVAL;
>> +
>> +	if (ctx->node_id == UINT32_MAX ||
>> +	    ctx->error_id == UINT32_MAX ||
>> +	    ctx->error_id == 0) {
>> +		igt_warn("Invalid node_id (%u) or error_id (%u) provided. "
>> +			 "node_id should be >= 0 and error_id should be >= 1.\n",
>> +			 ctx->node_id, ctx->error_id);
>> +		return -EINVAL;
>> +	}
>> +
>> +	ctx->error_value = UINT32_MAX;
>> +
>> +	ret = send_command(ctx, DRM_RAS_CMD_GET_ERROR_COUNTER);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (ctx->error_value == UINT32_MAX) {
>> +		igt_warn("No valid error counter reply: node_id=%u error_id=%u kernel_error=%d\n",
>> +			 ctx->node_id, ctx->error_id, ctx->last_nl_error);
>> +		return ctx->last_nl_error ? ctx->last_nl_error : -ENODATA;
>> +	}
>> +
>> +	igt_debug("Retrieved error counter: node_id=%u error_id=%u value=%u\n",
>> +		  ctx->node_id, ctx->error_id, ctx->error_value);
>> +
>> +	return 0;
>> +}
>> diff --git a/lib/igt_drm_netlink.h b/lib/igt_drm_netlink.h
>> index f681a3a81..92ac665e2 100644
>> --- a/lib/igt_drm_netlink.h
>> +++ b/lib/igt_drm_netlink.h
>> @@ -9,17 +9,31 @@
>>   #include <stdbool.h>
>>   #include <stdint.h>
> Okay so this change should add them I guess.
Ok. I will update it accordingly. Thanks
>
>>   
>> +#include <linux/genetlink.h>
>> +
>> +#include <netlink/attr.h>
>> +#include <netlink/handlers.h>
>> +#include <netlink/msg.h>
> None of these are used here though.
Ok. I will update it accordingly. Thanks
>
>>   #include <netlink/netlink.h>
>>   
>>   #include <drm-uapi/drm_ras.h>
>>   
>>   struct app_context {
>>   	struct nl_sock *sock;
>> +	uint32_t node_id;
>> +	uint32_t error_id;
>> +	uint32_t error_value;
>> +	int last_nl_error;
>> +	bool cmd_done;
>> +	bool reply_received;
>> +	bool ack_received;
>> +	bool response_required;
>>   	int family_id;
>>   };
>>   
>>   void igt_cleanup_nl_socket(struct app_context *ctx);
>>   int igt_init_nl_socket(struct app_context *ctx);
>> +int igt_get_error_counter(struct app_context *ctx);
> This is really inconsistent naming, though.

igt_init_nl_socket() and igt_cleanup_nl_socket() are the library 
functions to initialize and cleanup the netlink socket.

igt_get_error_counter() is the library function to get the error counter.

"igt_" is the prefix used for all the library functions, as suggested by 
Kamil.

I am not clear why this naming is inconsistent. Could you please 
elaborate your suggestion here.

Thanks.

>
>>   
>>   #endif /* IGT_DRM_NETLINK_H */