Re: [net PATCH v2 6/6] eth: fbnic: Handle FW mailbox completions flagged with an error
From: netdev-bot+sashiko@kernel.org
Date: 2026-09-17 21:12:11
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: Critical: 0 · High: 0 · Medium: 1 · Low: 0 - [Medium] FW_ERR handling does not release the outstanding-request bookkeeping: when the firmware completes a Tx descriptor with… -- eth: fbnic: Handle FW mailbox completions flagged with an error The patch adds a check for FBNIC_IPC_MBX_DESC_FW_ERR on both the Tx and Rx firmware mailboxes, counts the occurrences per mailbox in fbnic_fw_mbx.resp_error (also exported via debugfs), emits a rate limited warning, and drops the Rx page instead of parsing it. It also re-issues the bring-up capabilities request in fbnic_mbx_poll_tx_ready() when either resp_error counter advances.
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_csr.h b/drivers/net/ethernet/meta/fbnic/fbnic_csr.h index 14af30e189d6c..baba3471bf5a4 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_csr.h +++ b/drivers/net/ethernet/meta/fbnic/fbnic_csr.h@@ -1216,6 +1216,10 @@ enum { #define FBNIC_IPC_MBX_DESC_LEN_MASK DESC_GENMASK(63, 48) #define FBNIC_IPC_MBX_DESC_EOM DESC_BIT(46) #define FBNIC_IPC_MBX_DESC_ADDR_MASK DESC_GENMASK(45, 3) +/* Set with FW_CMPL when the FW completed a descriptor without successfully + * processing it (e.g. a mailbox DMA error); the completion has no valid data. + */ +#define FBNIC_IPC_MBX_DESC_FW_ERR DESC_BIT(2) #define FBNIC_IPC_MBX_DESC_FW_CMPL DESC_BIT(1) #define FBNIC_IPC_MBX_DESC_HOST_CMPL DESC_BIT(0)
[ ... ]
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_fw.c b/drivers/net/ethernet/meta/fbnic/fbnic_fw.c index 59aa879798b9f..6d7eb8479edf4 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_fw.c +++ b/drivers/net/ethernet/meta/fbnic/fbnic_fw.c@@ -292,6 +292,12 @@ static void fbnic_mbx_process_tx_msgs(struct fbnic_dev *fbd) if (!(desc & FBNIC_IPC_MBX_DESC_FW_CMPL)) break; + if (desc & FBNIC_IPC_MBX_DESC_FW_ERR) { + tx_mbx->resp_error++; + dev_warn_ratelimited(fbd->dev, + "FW completed a Tx mailbox request with an error\n"); + } + fbnic_mbx_unmap_and_free_msg(fbd, FBNIC_IPC_MBX_TX_IDX, head);
[Severity: Medium]
Should this path also release the completion registered for the request
that the firmware just abandoned?
The new comment in fbnic_csr.h says the FW_ERR completion "has no valid
data", so no response TLV will follow. Requests submitted through
fbnic_mbx_map_req_w_cmpl() leave a struct fbnic_fw_completion installed in
fbd->cmpl_data[], and fbnic_mbx_process_tx_msgs() here only bumps
resp_error and frees the page, so that slot stays armed.
For example, with a TSENE read flagged FW_ERR on the Tx descriptor:
fbnic_mac_get_sensor_asic()
...
if (!wait_for_completion_timeout(&fw_cmpl->done, 10 * HZ)) {
dev_err(fbd->dev, "Timed out waiting for TSENE read\n");
Does the hwmon reader then block for the full 10 seconds even though the
driver already knows at FW_ERR time that no answer is coming?
There is a second effect while that stale waiter is pending. In
fbnic_mbx_set_cmpl_slot():
for (i = 0; i < FBNIC_MBX_CMPL_SLOTS; i++) {
if (!fbd->cmpl_data[i])
free = i;
else if (fbd->cmpl_data[i]->msg_type == cmpl_data->msg_type)
return -EEXIST;
}
so a second request of the same msg_type in that window is rejected with
-EEXIST until the first waiter times out and clears its slot.
The driver already has a way to say "no response will arrive":
static void __fbnic_fw_evict_cmpl(struct fbnic_fw_completion *cmpl_data)
{
cmpl_data->result = -EPIPE;
complete(&cmpl_data->done);
}
but that is only reached from fbnic_mbx_evict_all_cmpl() in
fbnic_mbx_flush_tx() during mailbox teardown, never from the new
per-descriptor FW_ERR handling. Could the FW_ERR path look up the
matching completion (the TLV, and therefore its msg type, is still in
tx_mbx->buf_info[head].msg at this point) and complete it with an error?
quoted hunk ↗ jump to hunk
@@ -1673,6 +1679,13 @@ static void fbnic_mbx_process_rx_msgs(struct fbnic_dev *fbd) if (!(desc & FBNIC_IPC_MBX_DESC_FW_CMPL)) break; + if (desc & FBNIC_IPC_MBX_DESC_FW_ERR) { + rx_mbx->resp_error++; + dev_warn_ratelimited(fbd->dev, + "FW reported an error on an Rx mailbox message; dropping\n"); + goto next_page; + } + dma_sync_single_for_cpu(fbd->dev, rx_mbx->buf_info[head].addr, FBNIC_RX_PAGE_SIZE, DMA_FROM_DEVICE);
[Severity: Medium] The same question applies on the Rx side: when the dropped descriptor was the response to a request with a completion installed, nothing wakes the waiter either, so callers such as fbnic_flash_start(): if (fbnic_mbx_wait_for_cmpl(cmpl)) err = cmpl->result; else err = -ETIMEDOUT; burn the full FBNIC_MBX_RX_TO_SEC wait and report -ETIMEDOUT rather than an error. The retry added in fbnic_mbx_poll_tx_ready() covers the bring-up capabilities exchange, but the QSFP EEPROM read, coredump info/read and the FW upgrade start/write/finish requests all run after bring-up and are not covered. Is that intentional for this patch, or should the completion bookkeeping be released for those too? -- Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/178941996343.7700.9376081102002673062.stgit%40ahduyck-xeon-server.home.arpa