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Bhat" Subject: [PATCH v3 44/45] sparc: Use get/put_online_cpus_atomic() to prevent CPU offline 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, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com, David.Laight@aculab.com Date: Fri, 28 Jun 2013 01:30:47 +0530 Message-ID: <20130627200047.29830.27378.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130627195136.29830.10445.stgit@srivatsabhat.in.ibm.com> References: <20130627195136.29830.10445.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062719-5564-0000-0000-0000088FC884 Cc: linux-arch@vger.kernel.org, nikunj@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, linux-pm@vger.kernel.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, xiaoguangrong@linux.vnet.ibm.com, Sam Ravnborg , sbw@mit.edu, Dave Kleikamp , wangyun@linux.vnet.ibm.com, "Srivatsa S. Bhat" , netdev@vger.kernel.org, sparclinux@vger.kernel.org, Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, "David S. Miller" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Once stop_machine() is gone from the CPU offline path, we won't be able to depend on disabling preemption 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: "David S. Miller" Cc: Sam Ravnborg Cc: Thomas Gleixner Cc: Dave Kleikamp Cc: sparclinux@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/sparc/kernel/smp_64.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index 77539ed..4f71a95 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -792,7 +792,9 @@ static void smp_cross_call_masked(unsigned long *func, u32 ctx, u64 data1, u64 d /* Send cross call to all processors except self. */ static void smp_cross_call(unsigned long *func, u32 ctx, u64 data1, u64 data2) { + get_online_cpus_atomic(); smp_cross_call_masked(func, ctx, data1, data2, cpu_online_mask); + put_online_cpus_atomic(); } extern unsigned long xcall_sync_tick; @@ -896,7 +898,7 @@ void smp_flush_dcache_page_impl(struct page *page, int cpu) atomic_inc(&dcpage_flushes); #endif - this_cpu = get_cpu(); + this_cpu = get_online_cpus_atomic(); if (cpu == this_cpu) { __local_flush_dcache_page(page); @@ -922,7 +924,7 @@ void smp_flush_dcache_page_impl(struct page *page, int cpu) } } - put_cpu(); + put_online_cpus_atomic(); } void flush_dcache_page_all(struct mm_struct *mm, struct page *page) @@ -933,7 +935,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page) if (tlb_type == hypervisor) return; - preempt_disable(); + get_online_cpus_atomic(); #ifdef CONFIG_DEBUG_DCFLUSH atomic_inc(&dcpage_flushes); @@ -958,7 +960,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page) } __local_flush_dcache_page(page); - preempt_enable(); + put_online_cpus_atomic(); } void __irq_entry smp_new_mmu_context_version_client(int irq, struct pt_regs *regs) @@ -1150,6 +1152,7 @@ void smp_capture(void) { int result = atomic_add_ret(1, &smp_capture_depth); + get_online_cpus_atomic(); if (result == 1) { int ncpus = num_online_cpus(); @@ -1166,6 +1169,7 @@ void smp_capture(void) printk("done\n"); #endif } + put_online_cpus_atomic(); } void smp_release(void)