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firelzrd / bore-scheduler

BORE (Burst-Oriented Response Enhancer) CPU Scheduler
GNU General Public License v2.0
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unsigned int possible to wrap up #1

Closed hamadmarri closed 2 years ago

hamadmarri commented 2 years ago

https://github.com/firelzrd/bore-scheduler/blob/3f2dd489818750e43b9cb37192b6e3381fb1a5f8/patches/5.15.10-rt24-xanmod1_bore19.3-cacule.patch#L270

There is a chance that nr_running equals to zero even if there is a task. By decrementing it by 1, this will results to unsigned int max. To be safe, it is better to use h_nr_running since this includes all normal, batch, and idle tasks.

unsigned int        h_nr_running;      /* SCHED_{NORMAL,BATCH,IDLE} */

To be safer, make a if check for zero case.

Thank you

firelzrd commented 2 years ago

Thank you very much for pointing that out, Hamad. After ptr reported me about his 5.15-bore backport failing to boot in a few people's rigs, I was reviewing my own code when I found the same thing and thought the same way that it "could be logically possible" that nr_running == 0, but I left it since if 0-1 == uint_max, in this case the division result would be like super small but at least not error, and also I thought if nr_running is less than 2, then task switch wouldn't be invoked. I admit I was being too optimistic. I've just fixed the code and tagged/pushed it as 20.1 (#20 Fix 1). Thanks again for your contribution!

firelzrd commented 2 years ago

It has been fixed in #20.1. Now closing the issue.