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
| ||
|
Date: Mon, 14 Jun 2010 08:52:25 +0200 From: Lothar Waßmann <LW@...O-electronics.de> To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>, Jeremy Kerr <jeremy.kerr@...onical.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Ben Dooks <ben-linux@...ff.org> Subject: Re: [RFC,PATCH 1/2] Add a common struct clk Hi, Uwe Kleine-König writes: > Hello Lothar, > > On Mon, Jun 14, 2010 at 08:39:21AM +0200, Lothar Waßmann wrote: > > Hi, > > > > Benjamin Herrenschmidt writes: > > > On Fri, 2010-06-11 at 12:08 +0200, Lothar Waßmann wrote: > > > > Hi, > > > > > > > > > > > > Using a mutex in clk_enable()/clk_disable() is a bad idea, since that > > > > > > > > makes it impossible to call those functions in interrupt context. > > > > > IMHO if a device generates an irq its clock should already be on. This > > > > > way you don't need to enable or disable a clock in irq context. > > > > > > > > > You may want to disable a clock in the IRQ handler. The VPU driver in > > > > the Freescale BSP for i.MX51 does exactly this. > > > > Anyway I don't see any reason for using a mutex here instead of > > > > spin_lock_irq_save() as all other implementations do. > > > > > > Because you suddenly make it impossible to sleep inside enable/disable > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > ??? > > All implementations so far use spin_lock_irq_save()! > > > > How would you be able to sleep with a mutex held? > > If you hold a lock you must not sleep, no matter what sort of lock it > > is. > That's wrong. With a mutex hold you may sleep. > OK, you're right. But still all other implementations (omap, mxc, davinci,...) use spin_lock_irqsave() to protect the enable/disable functions and don't seem to have any problem with this. Is there any reason to change this, or make it inconsistent for one arch? And arch/arm/plat-s3c/clock.c has the following comment: |/* We originally used an mutex here, but some contexts (see resume) | * are calling functions such as clk_set_parent() with IRQs disabled | * causing an BUG to be triggered. | */ |DEFINE_SPINLOCK(clocks_lock); Lothar Waßmann -- ___________________________________________________________ Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10 Geschäftsführer: Matthias Kaussen Handelsregistereintrag: Amtsgericht Aachen, HRB 4996 www.karo-electronics.de | info@...o-electronics.de ___________________________________________________________ -- 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/
Powered by blists - more mailing lists