Messages in this thread | | | Date | Sun, 22 Sep 2013 20:44:23 +0800 | From | Jia He <> | Subject | Re: [PATCH] ipc/sem.c: fix update sem_otime when calling sem_op in semaphore initialization |
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On Sun, 22 Sep 2013 12:00:21 +0200 from bitbucket@online.de wrote: > On Sun, 2013-09-22 at 17:34 +0800, Jia He wrote: >> Thanks for the comments, but pls add my email as "from jiakernel@gmail.com" >> if you have a better implementation.U know, it is my first kernel patch, maybe >> will give me a brilliant memory in the future :) > You can have the blame if you like :) > >> Anyway, your implementation looks not correct to me. Because from "man semop" >> sem_otime will record the last sem operation time of semop. If you change the >> otime in semget(), it changes the meanings in stardard, doesn't it? > A Linux kernel doing a semop in 1970 would be a kinda neat trick :) I will try to make it more clear comes to my test case again:
process_a(server) process_b(client) semget() <-seems you choose to set it here --------------- <1> -------------------- semctl(SETVAL) semop() semget() setctl(IP_STAT) for(;;) { check until sem_otime > 0 } And assume that schedule() happenes at <1>, then sem_otime will >0 in process_b's for(;;), but at that time, the process_a's semctl() hasn't been called yet.
> > -Mike > > . >
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