Hi, Greg K-H, I found the scheduler isn't working correct. When I run an application instead of the shell, and when I call sleep() inside the application, it hangs. So I have to investigate about the clock settings first(in dts, etc). (The serial port is 8250 compatible uart that we've been using). Thank you. Chan Kim >-----Original Message----- >From: Greg KH <greg@xxxxxxxxx> >Sent: Wednesday, September 21, 2022 8:16 PM >To: Chan Kim <ckim@xxxxxxxxxx> >Cc: kernelnewbies@xxxxxxxxxxxxxxxxx >Subject: Re: how to debug... program hangs while downing for write a rwsem > >On Wed, Sep 21, 2022 at 08:02:50PM +0900, Chan Kim wrote: >> Hello kernel experts and users, >> >> I'm trying to boot linux-5.10.0-rc5 on our arm64 board (using >> neoverse-v1 core). > >5.10-rc5 is very very very old and obsolete, and not even a real release. >Why are you using that specific kernel version? > >At the very least, use a released and supported 5.10.y tree, but even >better, use the latest 5.19.y release. > >> After the shell comes up, when I press enter key at the prompt, it >> gives me another prompt. >> But when I press enter key again, it stops responding. >> After inspecting where the program hangs, I found it hangs in function >> tty_set_termios while downing the rwsem. >> Please see below where I marked "<===== this line "". (in file >> drivers/tty/tty_ioctl.c) >> >> int tty_set_termios(struct tty_struct *tty, struct ktermios >> *new_termios) { >> struct ktermios old_termios; >> struct tty_ldisc *ld; >> >> WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY && >> tty->driver->subtype == PTY_TYPE_MASTER); >> /* >> * Perform the actual termios internal changes under lock. >> */ >> >> >> /* FIXME: we need to decide on some locking/ordering semantics >> for the set_termios notification eventually */ >> down_write(&tty->termios_rwsem); <====== this >> line > >What serial driver are you using that is causing this problem? > >thanks, > >greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies