linux-kernel - Re: + s390-tty-prepare-for-put_char-to-return-success-fail.patch added to -mm tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080415072117.GA4177@osiris.boeblingen.de.ibm.com>
Date:	Tue, 15 Apr 2008 09:21:18 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	alan@...rguk.ukuu.org.uk, alan@...hat.com, borntraeger@...ibm.com,
	peter.oberparleiter@...ibm.com, schwidefsky@...ibm.com,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: + s390-tty-prepare-for-put_char-to-return-success-fail.patch
	added to -mm tree

>   * NOTE: include/linux/tty_driver.h specifies that a character should be
>   * ignored if there is no room in the queue. This driver implements a different
>   * semantic in that it will block when there is no more room left.
> + *
> + * FIXME: putchar can currently be called from BH and other non blocking
> + * handlers so  this semantic isn't a good idea.
>   */
> -static void
> +static int
>  sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
>  {
>  	__sclp_vt220_write(&ch, 1, 0, 0, 1);
> +	return 1;

Uh, oh... the comment above used to mean "block if in schedulable context or
busy wait otherwise". Figuring out which context we were in was done via
in_atomic(), which was broken on !SMP anyway, so that had to go.
So the last parameter for __sclp_vt220_write is now an indicator if scheduling
is allowed or not (1 means yes). Somebody told me that the put_char routine
will only be called from schedulable context, which now doesn't seem to be
true?!
For the console functions we pass indeed 0 to __sclp_vt220_write since printk
may be called within any context. Is that also true for the tty put_char
routine?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/