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[PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU o

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
Subject: [PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline
From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Date: Wed, 26 Jun 2013 02:02:57 +0530
Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>, David Daney <david.daney@cavium.com>, Yong Zhang <yong.zhang0@gmail.com>, Thomas Gleixner <tglx@linutronix.de>, Sanjay Lal <sanjayl@kymasys.com>, "Steven J. Hill" <sjhill@mips.com>, John Crispin <blogic@openwrt.org>, Florian Fainelli <florian@openwrt.org>, linux-mips@linux-mips.org, "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
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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: Ralf Baechle <ralf@linux-mips.org>
Cc: David Daney <david.daney@cavium.com>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Cc: "Steven J. Hill" <sjhill@mips.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 arch/mips/kernel/cevt-smtc.c |    7 +++++++
 arch/mips/kernel/smp.c       |   16 ++++++++--------
 arch/mips/kernel/smtc.c      |   12 ++++++++++++
 arch/mips/mm/c-octeon.c      |    4 ++--
 4 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/arch/mips/kernel/cevt-smtc.c b/arch/mips/kernel/cevt-smtc.c
index 9de5ed7..2e6c0cd 100644
--- a/arch/mips/kernel/cevt-smtc.c
+++ b/arch/mips/kernel/cevt-smtc.c
@@ -11,6 +11,7 @@
 #include <linux/interrupt.h>
 #include <linux/percpu.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 #include <linux/irq.h>
 
 #include <asm/smtc_ipi.h>
@@ -84,6 +85,8 @@ static int mips_next_event(unsigned long delta,
        unsigned long nextcomp = 0L;
        int vpe = current_cpu_data.vpe_id;
        int cpu = smp_processor_id();
+
+       get_online_cpus_atomic();
        local_irq_save(flags);
        mtflags = dmt();
 
@@ -164,6 +167,7 @@ static int mips_next_event(unsigned long delta,
        }
        emt(mtflags);
        local_irq_restore(flags);
+       put_online_cpus_atomic();
        return 0;
 }
 
@@ -177,6 +181,7 @@ void smtc_distribute_timer(int vpe)
        unsigned long nextstamp;
        unsigned long reference;
 
+       get_online_cpus_atomic();
 
 repeat:
        nextstamp = 0L;
@@ -229,6 +234,8 @@ repeat:
                        > (unsigned long)LONG_MAX)
                                goto repeat;
        }
+
+       put_online_cpus_atomic();
 }
 
 
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 6e7862a..be152b6 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -250,12 +250,12 @@ static inline void smp_on_other_tlbs(void (*func) (void 
*info), void *info)
 
 static inline void smp_on_each_tlb(void (*func) (void *info), void *info)
 {
-       preempt_disable();
+       get_online_cpus_atomic();
 
        smp_on_other_tlbs(func, info);
        func(info);
 
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 /*
@@ -273,7 +273,7 @@ static inline void smp_on_each_tlb(void (*func) (void 
*info), void *info)
 
 void flush_tlb_mm(struct mm_struct *mm)
 {
-       preempt_disable();
+       get_online_cpus_atomic();
 
        if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
                smp_on_other_tlbs(flush_tlb_mm_ipi, mm);
@@ -287,7 +287,7 @@ void flush_tlb_mm(struct mm_struct *mm)
        }
        local_flush_tlb_mm(mm);
 
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 struct flush_tlb_data {
@@ -307,7 +307,7 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned 
long start, unsigned l
 {
        struct mm_struct *mm = vma->vm_mm;
 
-       preempt_disable();
+       get_online_cpus_atomic();
        if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
                struct flush_tlb_data fd = {
                        .vma = vma,
@@ -325,7 +325,7 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned 
long start, unsigned l
                }
        }
        local_flush_tlb_range(vma, start, end);
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 static void flush_tlb_kernel_range_ipi(void *info)
@@ -354,7 +354,7 @@ static void flush_tlb_page_ipi(void *info)
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 {
-       preempt_disable();
+       get_online_cpus_atomic();
        if ((atomic_read(&vma->vm_mm->mm_users) != 1) || (current->mm != 
vma->vm_mm)) {
                struct flush_tlb_data fd = {
                        .vma = vma,
@@ -371,7 +371,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned 
long page)
                }
        }
        local_flush_tlb_page(vma, page);
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 static void flush_tlb_one_ipi(void *info)
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
index 75a4fd7..3cda8eb 100644
--- a/arch/mips/kernel/smtc.c
+++ b/arch/mips/kernel/smtc.c
@@ -21,6 +21,7 @@
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
@@ -1143,6 +1144,8 @@ static irqreturn_t ipi_interrupt(int irq, void *dev_idm)
         * for the current TC, so we ought not to have to do it explicitly here.
         */
 
+       get_online_cpus_atomic();
+
        for_each_online_cpu(cpu) {
                if (cpu_data[cpu].vpe_id != my_vpe)
                        continue;
@@ -1180,6 +1183,8 @@ static irqreturn_t ipi_interrupt(int irq, void *dev_idm)
                }
        }
 
+       put_online_cpus_atomic();
+
        return IRQ_HANDLED;
 }
 
@@ -1383,6 +1388,7 @@ void smtc_get_new_mmu_context(struct mm_struct *mm, 
unsigned long cpu)
         * them, let's be really careful...
         */
 
+       get_online_cpus_atomic();
        local_irq_save(flags);
        if (smtc_status & SMTC_TLB_SHARED) {
                mtflags = dvpe();
@@ -1438,6 +1444,7 @@ void smtc_get_new_mmu_context(struct mm_struct *mm, 
unsigned long cpu)
        else
                emt(mtflags);
        local_irq_restore(flags);
+       put_online_cpus_atomic();
 }
 
 /*
@@ -1496,6 +1503,7 @@ void smtc_cflush_lockdown(void)
 {
        int cpu;
 
+       get_online_cpus_atomic();
        for_each_online_cpu(cpu) {
                if (cpu != smp_processor_id()) {
                        settc(cpu_data[cpu].tc_id);
@@ -1504,6 +1512,7 @@ void smtc_cflush_lockdown(void)
                }
        }
        mips_ihb();
+       put_online_cpus_atomic();
 }
 
 /* It would be cheating to change the cpu_online states during a flush! */
@@ -1512,6 +1521,8 @@ void smtc_cflush_release(void)
 {
        int cpu;
 
+       get_online_cpus_atomic();
+
        /*
         * Start with a hazard barrier to ensure
         * that all CACHE ops have played through.
@@ -1525,4 +1536,5 @@ void smtc_cflush_release(void)
                }
        }
        mips_ihb();
+       put_online_cpus_atomic();
 }
diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c
index 8557fb5..8e1bcf6 100644
--- a/arch/mips/mm/c-octeon.c
+++ b/arch/mips/mm/c-octeon.c
@@ -73,7 +73,7 @@ static void octeon_flush_icache_all_cores(struct 
vm_area_struct *vma)
        mb();
        octeon_local_flush_icache();
 #ifdef CONFIG_SMP
-       preempt_disable();
+       get_online_cpus_atomic();
        cpu = smp_processor_id();
 
        /*
@@ -88,7 +88,7 @@ static void octeon_flush_icache_all_cores(struct 
vm_area_struct *vma)
        for_each_cpu(cpu, &mask)
                octeon_send_ipi_single(cpu, SMP_ICACHE_FLUSH);
 
-       preempt_enable();
+       put_online_cpus_atomic();
 #endif
 }
 


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