Messages in this thread | | | Date | Sat, 10 Mar 2007 02:54:00 -0800 | From | "Luong Ngo" <> | Subject | Re: Sleeping thread not receive signal until it wakes up |
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On 3/10/07, Sergey Vlasov <vsu@altlinux.ru> wrote: > On Fri, 9 Mar 2007 16:10:29 -0800 Luong Ngo wrote: > > > Thanks Parav, adding singal_allow(SIGALRM) wakeup the blocking > > interruptible_sleep_on and checking the signal_pending would return > > true now. > > This means that there is also a bug in your userspace program - > somehow when it invokes ioctl(), it has SIGALRM blocked. Use > sigprocmask() (or pthread_sigmask() if your program is multithreaded) > to ensure that SIGALRM is not blocked when you are expecting it to be > processed. (Even if your program does not block SIGALRM, it may > inherit a blocked SIGALRM from another program which have started it, > so the safest way is to unblock SIGALRM explicitly.) > When creating the thread, which would make ioctl call, the parent thread does not call any sigprocmask so I assume that means none of the signals is masked. Hence SIGALRM should be received by the thread. But this did not happen until I call allow_signal explicitly in the ioctl handler of the driver. I did not call sigprocmask with SIG_BLOCK.
> Using allow_signal() is needed only if you create a kernel thread and > want that thread to handle signals. > Could the execution of ioctl in the driver be done in a kernel thread that created to handle the user ioctl request and therefore it needs allow_signal?
Thanks a lot, LNgo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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