Re: manipulating sigmask from filesystems and drivers

From: Linus Torvalds (
Date: Thu Aug 01 2002 - 14:09:04 EST

On Wed, 31 Jul 2002, David Howells wrote:
> Can you comment on whether a driver is allowed to block signals like this, and
> whether they should be waiting in TASK_UNINTERRUPTIBLE?

They should be waiting in TASK_UNINTERRUPTIBLE, and we should add a flag
to distinguish between "increases load average" and "doesn't". So you
could have

        TASK_WAKESIGNAL - wake on all signals
        TASK_WAKEKILL - wake on signals that are deadly
        TASK_NOSIGNAL - don't wake on signals
        TASK_LOADAVG - counts toward loadaverage


and then people who wanted to could use other combinations. The
TASK_WAKEKILL thing is useful - there are many loops that cannot exit
until they have a result, simply because the calling conventions require
that. Th emost common example is disk wait.

HOWEVER, if they are killed by a signal, the calling convention doesn't
matter, and the read() or whatever could just return 0 (knowing that the
process will never see it), and leave a locked page locked. Things like
generic_file_read() could easily use this, and make processes killable
even when they are waiting for a hung NFS mount - regardless of any soft
mount issues, and without NFS having to have special code.

In the end, I'm too lazy, and I don't care. So I can only tell you how it
_should_ be done, and maybe you can tell somebody else until the sucker to
actually do it is found.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

This archive was generated by hypermail 2b29 : Wed Aug 07 2002 - 22:00:16 EST