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Before I look in the details of the patches, > > I would like make a comment below. > > > > > Reproducing the race needs an IO that can be held at the target for > > > longer than the host's io_timeout without being failed. The first three > > > patches give miniublk that ability, since there was previously no way to > > > talk to a running ublk server at all: > > > > > > 1/5 adds a loopback UDP control channel to the daemon, served by a > > > detached thread, one reply datagram per request > > > 2/5 adds an INJECT_DELAY command which delays a given number of reads > > > or writes as an io_uring timeout on the queue's own ring > > > 3/5 exposes it as "miniublk inject", which returns only once the > > > daemon has armed the delay, so a test can start IO immediately > > > without racing it > > > > It is interesting to implement the delay feature to miniublk, and use it as the > > testing tool. But I'm not sure if this is the best approach because of two > > points. First, scsi_debug has jdelay and ndelay options. I wonder if this > > existing feature can fulfill the requirements of the new test case. Second, when > > rublk [*] is available in the PATH of the test system, blktests detect it and > > use it instead of miniublk. I guess the added delay feature is not available in > > rublk, and the test case won't work well. What do you think of these points? > > > > The two points make sense to me. Let me look at scsi_debug delay > injection mechanism first and see if it can be used here. I will also > look at rublk. Thanks for the pointers. I've learned that now delay injection is being added to the block layer [*]. This looks more generic and could be the best way for this use case. [*] https://lore.kernel.org/linux-block/20260928221634.43239-1-haris.iqbal@linux.dev/