From: Manfred Spraul Date: Tue, 09 Sep 2008 18:49:04 +0000 Subject: Re: [PATCH] prevent sparc64 from invoking irq handlers on offline Message-Id: <48C6C520.5070103@colorfullife.com> List-Id: References: <20080903004211.GD6748@linux.vnet.ibm.com> <20080903.022138.31681256.davem@davemloft.net> <20080903154217.GA6807@linux.vnet.ibm.com> <20080908.171708.43575256.davem@davemloft.net> In-Reply-To: <20080908.171708.43575256.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Miller Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, wli@holomorphy.com, sparclinux@vger.kernel.org, akpm@linux-foundation.org David Miller wrote: > And IPI handler runs in HW irq context, therefore such an IPI-creates-an-IPI > should not be allowed, at least not directly. > > Actually the restriction seems to be that an IPI cannot be sent when > "irqs_disabled()", hmmm... > > Does this apply to smp_send_reschedule() as well? A [rare] codepath in the current rcu code does to trigger quiescent states on remote cpus. -- Manfred