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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23. 04. 24, 18:33, Linus Torvalds wrote: > ... and use it to limit the virtual terminals to just N_TTY. They are > kind of special, and in particular, the "con_write()" routine violates > the "writes cannot sleep" rule that some ldiscs rely on. > > This avoids the > > BUG: sleeping function called from invalid context at kernel/printk/printk.c:2659 > > when N_GSM has been attached to a virtual console, and gsmld_write() > calls con_write() while holding a spinlock, and con_write() then tries > to get the console lock. ..> --- a/drivers/tty/tty_ldisc.c > +++ b/drivers/tty/tty_ldisc.c > @@ -545,6 +545,12 @@ int tty_set_ldisc(struct tty_struct *tty, int disc) > goto out; > } > > + if (tty->ops->ldisc_ok) { > + retval = tty->ops->ldisc_ok(tty, disc); > + if (retval) > + goto out; This caught my eye as it looks like: if (ldisc_ok) die; Perhaps dub it ldisc_check()? Alternatively, make it return a bool and invert the logic here? That would make the ugly ternary in con_ldisc_ok() go away too. But whatever, it finally evades that group of bugs. Now, I am not sure what the problem with attaching some weird ldisc to a pty was. I will take a look next week (I am unavailable ATM). thanks, -- js suse labs