From: 'Simon Horman' <[email protected]>

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---
iavf: refactor virtchnl polling into single function

This commit consolidates the init-time and runtime virtchnl message polling
logic into a single enhanced iavf_poll_virtchnl_msg() function.

diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c 
b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
--- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
[ ... ]
> +int iavf_poll_virtchnl_msg(struct iavf_hw *hw, struct iavf_arq_event_info 
> *event,
> +                        enum virtchnl_ops op_to_poll, unsigned int 
> timeout_ms,
> +                        bool (*condition)(struct iavf_adapter *, const void 
> *),
> +                        const void *cond_data)
>  {
[ ... ]
> +     do {
> +             if (timeout_ms && iavf_virtchnl_completion_done(adapter, 
> condition,
> +                                                             cond_data, 
> op_to_poll))
> +                     return 0;
>  
> +             status = iavf_clean_arq_element(hw, event, &pending);
> +             if (status == IAVF_SUCCESS) {
> +                     received_op = (enum 
> virtchnl_ops)le32_to_cpu(event->desc.cookie_high);
>  
> +                     /* Handle reset events specially */
> +                     if (received_op == VIRTCHNL_OP_EVENT) {
> +                             struct virtchnl_pf_event *vpe =
> +                                     (struct virtchnl_pf_event 
> *)event->msg_buf;
>  
> +                             if (vpe->event != 
> VIRTCHNL_EVENT_RESET_IMPENDING)
> +                                     continue;

If received_op is VIRTCHNL_OP_EVENT but not VIRTCHNL_EVENT_RESET_IMPENDING,
the loop executes continue. Does this mean that during runtime polling (when
timeout_ms > 0), other asynchronous events like VIRTCHNL_EVENT_LINK_CHANGE
bypass iavf_virtchnl_completion() entirely and get discarded?

> +
> +                             dev_info(&adapter->pdev->dev,
> +                                      "Reset indication received from the 
> PF\n");
> +                             if (!(adapter->flags & IAVF_FLAG_RESET_PENDING))
> +                                     iavf_schedule_reset(adapter,
> +                                                         
> IAVF_FLAG_RESET_PENDING);
> +
> +                             return -EIO;
> +                     }
> +
> +                     v_retval = le32_to_cpu(event->desc.cookie_low);
> +
> +                     if (!timeout_ms) {
> +                             if (received_op == op_to_poll)
> +                                     return virtchnl_status_to_errno((enum 
> virtchnl_status_code)
> +                                                     v_retval);
> +                     } else {
> +                             iavf_virtchnl_completion(adapter, received_op,
> +                                                      (enum 
> iavf_status)v_retval,
> +                                                      event->msg_buf, 
> event->msg_len);
> +                     }
> +
> +                     if (pending)
> +                             continue;

When pending is true, the loop proceeds to the next iteration before executing
the memset buffer clearing code below. Might this leave stale data in
event->msg_buf for the next iavf_clean_arq_element() call if the subsequent
message is smaller than the previous one? The original implementation zeroed
the buffer before checking pending.

> +             } else if (!timeout_ms) {
> +                     return iavf_status_to_errno(status);
> +             }
>  
> +             if (timeout_ms) {
> +                     memset(event->msg_buf, 0, IAVF_MAX_AQ_BUF_SIZE);

The size passed to memset is hardcoded to IAVF_MAX_AQ_BUF_SIZE. If a caller
ever provides a timeout but passes a smaller buffer in the event structure,
could this write out of bounds?

For example, other callers like iavf_get_vf_supported_rxdids() use an 8-byte
stack variable for event->msg_buf with event->buf_len set to 8. Would it be
safer to use event->buf_len here instead of the hardcoded macro?

> +                     usleep_range(50, 75);
>               }
>  
> +     } while (!timeout_ms || time_before(jiffies, timeout));

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