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a09721dd47
The following happened on an i.MX25 using flexcan with many packets on
the bus:
The rx-offload queue reached a length more than skb_queue_len_max. In
can_rx_offload_offload_one() the drop variable was set to true which
made the call to .mailbox_read() (here: flexcan_mailbox_read()) to
_always_ return ERR_PTR(-ENOBUFS) and drop the rx'ed CAN frame. So
can_rx_offload_offload_one() returned ERR_PTR(-ENOBUFS), too.
can_rx_offload_irq_offload_fifo() looks as follows:
| while (1) {
| skb = can_rx_offload_offload_one(offload, 0);
| if (IS_ERR(skb))
| continue;
| if (!skb)
| break;
| ...
| }
The flexcan driver wrongly always returns ERR_PTR(-ENOBUFS) if drop is
requested, even if there is no CAN frame pending. As the i.MX25 is a
single core CPU, while the rx-offload processing is active, there is
no thread to process packets from the offload queue. So the queue
doesn't get any shorter and this results is a tight loop.
Instead of always returning ERR_PTR(-ENOBUFS) if drop is requested,
return NULL if no CAN frame is pending.
Changes since v1: https://lore.kernel.org/all/20220810144536.389237-1-u.kleine-koenig@pengutronix.de
- don't break in can_rx_offload_irq_offload_fifo() in case of an error,
return NULL in flexcan_mailbox_read() in case of no pending CAN frame
instead
Fixes:
|
||
|---|---|---|
| .. | ||
| flexcan-core.c | ||
| flexcan-ethtool.c | ||
| flexcan.h | ||
| Makefile | ||