From: "Paul E. McKenney" Date: Sun, 31 Aug 2008 17:33:49 +0000 Subject: [PATCH] prevent sparc64 from invoking irq handlers on offline CPUs Message-Id: <20080831173349.GA15393@linux.vnet.ibm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org Cc: davem@davemloft.net, wli@holomorphy.com, sparclinux@vger.kernel.org, manfred@colorfullife.com, akpm@linux-foundation.org Make sparc64 refrain from clearing a given to-be-offlined CPU's bit in the cpu_online_mask until it has processed pending irqs. This change prevents other CPUs from being blindsided by an apparently offline CPU nevertheless changing globally visible state. Signed-off-by: Paul E. McKenney --- smp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c index 743ccad..b83a683 100644 --- a/arch/sparc64/kernel/smp.c +++ b/arch/sparc64/kernel/smp.c @@ -1305,10 +1305,6 @@ int __cpu_disable(void) c->core_id = 0; c->proc_id = -1; - spin_lock(&call_lock); - cpu_clear(cpu, cpu_online_map); - spin_unlock(&call_lock); - smp_wmb(); /* Make sure no interrupts point to this cpu. */ @@ -1318,6 +1314,10 @@ int __cpu_disable(void) mdelay(1); local_irq_disable(); + spin_lock(&call_lock); + cpu_clear(cpu, cpu_online_map); + spin_unlock(&call_lock); + return 0; }