From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v5 39/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Tue, 22 Jan 2013 13:13:47 +0530 Message-ID: <20130122074344.13822.45560.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, fweisbec@gmail.com, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org Return-path: In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Srivatsa S. Bhat --- arch/powerpc/mm/mmu_context_nohash.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c index e779642..29f58cf 100644 --- a/arch/powerpc/mm/mmu_context_nohash.c +++ b/arch/powerpc/mm/mmu_context_nohash.c @@ -196,6 +196,7 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) /* No lockless fast path .. yet */ raw_spin_lock(&context_lock); + get_online_cpus_atomic(); pr_hard("[%d] activating context for mm @%p, active=%d, id=%d", cpu, next, next->context.active, next->context.id); @@ -279,6 +280,7 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) /* Flick the MMU and release lock */ pr_hardcont(" -> %d\n", id); set_context(id, next->pgd); + put_online_cpus_atomic(); raw_spin_unlock(&context_lock); }