Re: [PATCH v2 3/4] cxl/events: Bound the per-log Get Event Records loop

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Returning -EIO after capping the event log passes causes an infinite IRQ storm rather than letting the caller give up on the log.
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commit f19a605d6e7399b93479014db2d4bf98656f2614
Author: Anisa Su <anisa.su887@gmail.com>

cxl/events: Bound the per-log Get Event Records loop

This commit bounds the cxl_mem_get_records_log() loop to prevent a misbehaving
device from permanently stalling the event thread. It introduces a 128-pass cap,
returning an error if the cap is reached, and yields the CPU via cond_resched()
between passes.

> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 7c6c5b7450a54..5e49589727d59 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
[ ... ]
> @@ -1109,34 +1137,72 @@ static void cxl_mem_get_records_log(struct cxl_memdev_state *mds,
>  				type, rc);
>  			break;
>  		}
> +
> +		if (++passes == CXL_EVENT_LOG_MAX_PASSES) {
> +			dev_warn_ratelimited(dev,
> +				"Event log '%d': Still reporting records after %d passes, giving up",
> +				type, passes);
> +			rc = -EIO;
> +			break;
> +		}
> +		cond_resched();
>  	} while (nr_rec);

[Severity: High]
Does returning -EIO here cause an infinite interrupt storm rather than letting
the caller give up on the log?

When the 128-pass cap is reached, cxl_mem_get_records_log() returns -EIO. This
propagates to cxl_event_thread(), which breaks out of its event reading loop
and returns IRQ_HANDLED.

Because the event log is not empty, the device will immediately fire another
MSI. Since the thread returned IRQ_HANDLED, the kernel's spurious interrupt
detector won't disable the interrupt line. This wakes up cxl_event_thread()
again, which performs another 128 passes and exits, repeating endlessly.

Should the interrupt be persistently disabled or the log masked when we give
up on reading it?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260901002912.958-1-anisa.su@samsung.com?part=3