a4ec37f59e
to dequeue a packet. The tx path was trying to ensure that enough Xenbus TX ring slots existed but it didn't check to see whether the mbuf TX ring slots were also available. They get freed in xn_txeof() which occurs after transmission, rather than earlier on in the process. (The same happens under Linux too.) Due to whatever reason (CPU use, scheduling, memory constraints, whatever) the mbuf TX ring may not have enough slots free and would allocate slot 0. This is used as the freelist head pointer to represent "free" mbuf TX ring slots; setting this to an actual mbuf value rather than an id crashes the code. This commit introduces some basic code to track the TX mbuf ring use and then (hopefully!) ensures that enough slots are free in said TX mbuf ring before it enters the actual work loop. A few notes: * Similar logic needs to be introduced to check there are enough actual slots available in the xenbuf TX ring. There's some logic which is invoked earlier but it doesn't hard-check against the number of available ring slots. Its trivial to do; I'll do it in a subsequent commit. * As I've now commented in the source, it is likely possible to deadlock the driver under certain conditions where the rings aren't receiving any changes (which I should enumerate) and thus Xen doesn't send any further software interrupts. I need to make sure that the timer(s) are running right and the queues are periodically kicked. PR: 134926 |
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| balloon | ||
| blkback | ||
| blkfront | ||
| console | ||
| evtchn | ||
| netback | ||
| netfront | ||
| pcifront | ||
| xenpci | ||