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Open Source and information security mailing list archives
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Date: Thu, 01 Mar 2007 12:31:33 -0800 From: Zachary Amsden <zach@...are.com> To: Andrew Morton <akpm@...ux-foundation.org> CC: Rusty Russell <rusty@...tcorp.com.au>, Daniel Hecht <dhecht@...are.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: Bug in on_each_cpu? Andrew Morton wrote: > The handler for smp_call_function() is called with local interrupts > disabled (from the IPI handler). > > So to provide a consistent call environment for that handler, on_each_cpu() > will also disable local interrupts when making the direct call on this CPU. > > Similarly the !CONFIG_SMP version of on_each_cpu() disables local > interrupts when running the caller's function. > Yes, that is sensible. Something akin to on_each_cpu(synchronize_tscs) would certainly not like interrupts coming in. Similarly, acpi_nmi disable and probably rcu barriers as well. The irq disable here can very validly be used as a barrier, but trying to ensure preserved shared state with irq handlers over the call is a bug. If one had all the spare time in the world, a new "sense" of irq disable that communicated this fact would be nice from a static or dynamic checking perspective. Zach ------ sutra I.1 - atha linushasaanam - 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/
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