Merge branch 'ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  s390: remove arch specific smp_send_stop()
  panic: clean up kernel/panic.c
  panic, smp: provide smp_send_stop() wrapper on UP too
  panic: decrease oops_in_progress only after having done the panic
  generic-ipi: eliminate WARN_ON()s during oops/panic
  generic-ipi: cleanups
  generic-ipi: remove CSD_FLAG_WAIT
  generic-ipi: remove kmalloc()
  generic IPI: simplify barriers and locking

7 files changed, 304 insertions, 262 deletions

diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index 2009158a4502..72137bc907ac 100644
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -92,12 +92,6 @@ extern void arch_send_call_function_ipi(cpumask_t mask);
 #endif
 
 #ifndef CONFIG_SMP
-static inline void smp_send_stop(void)
-{
-        /* Disable all interrupts/machine checks */
-        __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
-}
-
 #define hard_smp_processor_id()         0
 #define smp_cpu_not_running(cpu)        1
 #endif
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index ce0efc6b26dc..ee9c21602228 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -64,7 +64,7 @@ static int raise_blk_irq(int cpu, struct request *rq)
                 data->info = rq;
                 data->flags = 0;
 
-                __smp_call_function_single(cpu, data);
+                __smp_call_function_single(cpu, data, 0);
                 return 0;
         }
 
diff --git a/include/linux/smp.h b/include/linux/smp.h
index bbacb7baa446..a69db820eed6 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -38,7 +38,7 @@ int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
 /*
  * main cross-CPU interfaces, handles INIT, TLB flush, STOP, etc.
  * (defined in asm header):
- */ 
+ */
 
 /*
  * stops all CPUs but the current one:
@@ -82,7 +82,8 @@ smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
         return 0;
 }
 
-void __smp_call_function_single(int cpuid, struct call_single_data *data);
+void __smp_call_function_single(int cpuid, struct call_single_data *data,
+                                int wait);
 
 /*
  * Generic and arch helpers
@@ -121,6 +122,8 @@ extern unsigned int setup_max_cpus;
 
 #else /* !SMP */
 
+static inline void smp_send_stop(void) { }
+
 /*
  *      These macros fold the SMP functionality into a single CPU system
  */
diff --git a/kernel/panic.c b/kernel/panic.c
index 32fe4eff1b89..3fd8c5bf8b39 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -8,19 +8,19 @@
  * This function is used through-out the kernel (including mm and fs)
  * to indicate a major problem.
  */
+#include <linux/debug_locks.h>
+#include <linux/interrupt.h>
+#include <linux/kallsyms.h>
+#include <linux/notifier.h>
 #include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/delay.h>
+#include <linux/random.h>
 #include <linux/reboot.h>
-#include <linux/notifier.h>
-#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/kexec.h>
+#include <linux/sched.h>
 #include <linux/sysrq.h>
-#include <linux/interrupt.h>
+#include <linux/init.h>
 #include <linux/nmi.h>
-#include <linux/kexec.h>
-#include <linux/debug_locks.h>
-#include <linux/random.h>
-#include <linux/kallsyms.h>
 #include <linux/dmi.h>
 
 int panic_on_oops;
@@ -52,19 +52,15 @@ EXPORT_SYMBOL(panic_blink);
  *
  *      This function never returns.
  */
-
 NORET_TYPE void panic(const char * fmt, ...)
 {
-        long i;
         static char buf[1024];
         va_list args;
-#if defined(CONFIG_S390)
-        unsigned long caller = (unsigned long) __builtin_return_address(0);
-#endif
+        long i;
 
         /*
-         * It's possible to come here directly from a panic-assertion and not
-         * have preempt disabled. Some functions called from here want
+         * It's possible to come here directly from a panic-assertion and
+         * not have preempt disabled. Some functions called from here want
          * preempt to be disabled. No point enabling it later though...
          */
         preempt_disable();
@@ -77,7 +73,6 @@ NORET_TYPE void panic(const char * fmt, ...)
 #ifdef CONFIG_DEBUG_BUGVERBOSE
         dump_stack();
 #endif
-        bust_spinlocks(0);
 
         /*
          * If we have crashed and we have a crash kernel loaded let it handle
@@ -86,14 +81,12 @@ NORET_TYPE void panic(const char * fmt, ...)
          */
         crash_kexec(NULL);
 
-#ifdef CONFIG_SMP
         /*
          * Note smp_send_stop is the usual smp shutdown function, which
          * unfortunately means it may not be hardened to work in a panic
          * situation.
          */
         smp_send_stop();
-#endif
 
         atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
@@ -102,19 +95,21 @@ NORET_TYPE void panic(const char * fmt, ...)
 
         if (panic_timeout > 0) {
                 /*
-                 * Delay timeout seconds before rebooting the machine. 
-                 * We can't use the "normal" timers since we just panicked..
-                 */
-                printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
+                 * Delay timeout seconds before rebooting the machine.
+                 * We can't use the "normal" timers since we just panicked.
+                 */
+                printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
+
                 for (i = 0; i < panic_timeout*1000; ) {
                         touch_nmi_watchdog();
                         i += panic_blink(i);
                         mdelay(1);
                         i++;
                 }
-                /*      This will not be a clean reboot, with everything
-                 *      shutting down.  But if there is a chance of
-                 *      rebooting the system it will be rebooted.
+                /*
+                 * This will not be a clean reboot, with everything
+                 * shutting down.  But if there is a chance of
+                 * rebooting the system it will be rebooted.
                  */
                 emergency_restart();
         }
@@ -127,38 +122,44 @@ NORET_TYPE void panic(const char * fmt, ...)
         }
 #endif
 #if defined(CONFIG_S390)
-        disabled_wait(caller);
+        {
+                unsigned long caller;
+
+                caller = (unsigned long)__builtin_return_address(0);
+                disabled_wait(caller);
+        }
 #endif
         local_irq_enable();
-        for (i = 0;;) {
+        for (i = 0; ; ) {
                 touch_softlockup_watchdog();
                 i += panic_blink(i);
                 mdelay(1);
                 i++;
         }
+        bust_spinlocks(0);
 }
 
 EXPORT_SYMBOL(panic);
 
 
 struct tnt {
-        u8 bit;
-        char true;
-        char false;
+        u8      bit;
+        char    true;
+        char    false;
 };
 
 static const struct tnt tnts[] = {
-        { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
-        { TAINT_FORCED_MODULE, 'F', ' ' },
-        { TAINT_UNSAFE_SMP, 'S', ' ' },
-        { TAINT_FORCED_RMMOD, 'R', ' ' },
-        { TAINT_MACHINE_CHECK, 'M', ' ' },
-        { TAINT_BAD_PAGE, 'B', ' ' },
-        { TAINT_USER, 'U', ' ' },
-        { TAINT_DIE, 'D', ' ' },
-        { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
-        { TAINT_WARN, 'W', ' ' },
-        { TAINT_CRAP, 'C', ' ' },
+        { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
+        { TAINT_FORCED_MODULE,          'F', ' ' },
+        { TAINT_UNSAFE_SMP,             'S', ' ' },
+        { TAINT_FORCED_RMMOD,           'R', ' ' },
+        { TAINT_MACHINE_CHECK,          'M', ' ' },
+        { TAINT_BAD_PAGE,               'B', ' ' },
+        { TAINT_USER,                   'U', ' ' },
+        { TAINT_DIE,                    'D', ' ' },
+        { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
+        { TAINT_WARN,                   'W', ' ' },
+        { TAINT_CRAP,                   'C', ' ' },
 };
 
 /**
@@ -195,7 +196,8 @@ const char *print_tainted(void)
                 *s = 0;
         } else
                 snprintf(buf, sizeof(buf), "Not tainted");
-        return(buf);
+
+        return buf;
 }
 
 int test_taint(unsigned flag)
@@ -211,7 +213,8 @@ unsigned long get_taint(void)
 
 void add_taint(unsigned flag)
 {
-        debug_locks = 0; /* can't trust the integrity of the kernel anymore */
+        /* can't trust the integrity of the kernel anymore: */
+        debug_locks = 0;
         set_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(add_taint);
@@ -266,8 +269,8 @@ static void do_oops_enter_exit(void)
 }
 
 /*
- * Return true if the calling CPU is allowed to print oops-related info.  This
- * is a bit racy..
+ * Return true if the calling CPU is allowed to print oops-related info.
+ * This is a bit racy..
  */
 int oops_may_print(void)
 {
@@ -276,20 +279,22 @@ int oops_may_print(void)
 
 /*
  * Called when the architecture enters its oops handler, before it prints
- * anything.  If this is the first CPU to oops, and it's oopsing the first time
- * then let it proceed.
+ * anything.  If this is the first CPU to oops, and it's oopsing the first
+ * time then let it proceed.
  *
- * This is all enabled by the pause_on_oops kernel boot option.  We do all this
- * to ensure that oopses don't scroll off the screen.  It has the side-effect
- * of preventing later-oopsing CPUs from mucking up the display, too.
+ * This is all enabled by the pause_on_oops kernel boot option.  We do all
+ * this to ensure that oopses don't scroll off the screen.  It has the
+ * side-effect of preventing later-oopsing CPUs from mucking up the display,
+ * too.
  *
- * It turns out that the CPU which is allowed to print ends up pausing for the
- * right duration, whereas all the other CPUs pause for twice as long: once in
- * oops_enter(), once in oops_exit().
+ * It turns out that the CPU which is allowed to print ends up pausing for
+ * the right duration, whereas all the other CPUs pause for twice as long:
+ * once in oops_enter(), once in oops_exit().
  */
 void oops_enter(void)
 {
-        debug_locks_off(); /* can't trust the integrity of the kernel anymore */
+        /* can't trust the integrity of the kernel anymore: */
+        debug_locks_off();
         do_oops_enter_exit();
 }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index 73513f4e19df..2325db2be31b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1110,7 +1110,7 @@ static void hrtick_start(struct rq *rq, u64 delay)
         if (rq == this_rq()) {
                 hrtimer_restart(timer);
         } else if (!rq->hrtick_csd_pending) {
-                __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd);
+                __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
                 rq->hrtick_csd_pending = 1;
         }
 }
diff --git a/kernel/smp.c b/kernel/smp.c
index bbedbb7efe32..858baac568ee 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -2,40 +2,82 @@
  * Generic helpers for smp ipi calls
  *
  * (C) Jens Axboe <jens.axboe@oracle.com> 2008
- *
  */
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/percpu.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 
 static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
-static LIST_HEAD(call_function_queue);
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
+
+static struct {
+        struct list_head        queue;
+        spinlock_t              lock;
+} call_function __cacheline_aligned_in_smp =
+        {
+                .queue          = LIST_HEAD_INIT(call_function.queue),
+                .lock           = __SPIN_LOCK_UNLOCKED(call_function.lock),
+        };
 
 enum {
-        CSD_FLAG_WAIT           = 0x01,
-        CSD_FLAG_ALLOC          = 0x02,
-        CSD_FLAG_LOCK           = 0x04,
+        CSD_FLAG_LOCK           = 0x01,
 };
 
 struct call_function_data {
-        struct call_single_data csd;
-        spinlock_t lock;
-        unsigned int refs;
-        struct rcu_head rcu_head;
-        unsigned long cpumask_bits[];
+        struct call_single_data csd;
+        spinlock_t              lock;
+        unsigned int            refs;
+        cpumask_var_t           cpumask;
 };
 
 struct call_single_queue {
-        struct list_head list;
-        spinlock_t lock;
+        struct list_head        list;
+        spinlock_t              lock;
+};
+
+static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
+        .lock                   = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
+};
+
+static int
+hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+        long cpu = (long)hcpu;
+        struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
+
+        switch (action) {
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                if (!alloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
+                                cpu_to_node(cpu)))
+                        return NOTIFY_BAD;
+                break;
+
+#ifdef CONFIG_CPU_HOTPLUG
+        case CPU_UP_CANCELED:
+        case CPU_UP_CANCELED_FROZEN:
+
+        case CPU_DEAD:
+        case CPU_DEAD_FROZEN:
+                free_cpumask_var(cfd->cpumask);
+                break;
+#endif
+        };
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
+        .notifier_call          = hotplug_cfd,
 };
 
 static int __cpuinit init_call_single_data(void)
 {
+        void *cpu = (void *)(long)smp_processor_id();
         int i;
 
         for_each_possible_cpu(i) {
@@ -44,29 +86,63 @@ static int __cpuinit init_call_single_data(void)
                 spin_lock_init(&q->lock);
                 INIT_LIST_HEAD(&q->list);
         }
+
+        hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
+        register_cpu_notifier(&hotplug_cfd_notifier);
+
         return 0;
 }
 early_initcall(init_call_single_data);
 
-static void csd_flag_wait(struct call_single_data *data)
+/*
+ * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
+ *
+ * For non-synchronous ipi calls the csd can still be in use by the
+ * previous function call. For multi-cpu calls its even more interesting
+ * as we'll have to ensure no other cpu is observing our csd.
+ */
+static void csd_lock_wait(struct call_single_data *data)
 {
-        /* Wait for response */
-        do {
-                if (!(data->flags & CSD_FLAG_WAIT))
-                        break;
+        while (data->flags & CSD_FLAG_LOCK)
                 cpu_relax();
-        } while (1);
+}
+
+static void csd_lock(struct call_single_data *data)
+{
+        csd_lock_wait(data);
+        data->flags = CSD_FLAG_LOCK;
+
+        /*
+         * prevent CPU from reordering the above assignment
+         * to ->flags with any subsequent assignments to other
+         * fields of the specified call_single_data structure:
+         */
+        smp_mb();
+}
+
+static void csd_unlock(struct call_single_data *data)
+{
+        WARN_ON(!(data->flags & CSD_FLAG_LOCK));
+
+        /*
+         * ensure we're all done before releasing data:
+         */
+        smp_mb();
+
+        data->flags &= ~CSD_FLAG_LOCK;
 }
 
 /*
- * Insert a previously allocated call_single_data element for execution
- * on the given CPU. data must already have ->func, ->info, and ->flags set.
+ * Insert a previously allocated call_single_data element
+ * for execution on the given CPU. data must already have
+ * ->func, ->info, and ->flags set.
  */
-static void generic_exec_single(int cpu, struct call_single_data *data)
+static
+void generic_exec_single(int cpu, struct call_single_data *data, int wait)
 {
         struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
-        int wait = data->flags & CSD_FLAG_WAIT, ipi;
         unsigned long flags;
+        int ipi;
 
         spin_lock_irqsave(&dst->lock, flags);
         ipi = list_empty(&dst->list);
@@ -74,24 +150,21 @@ static void generic_exec_single(int cpu, struct call_single_data *data)
         spin_unlock_irqrestore(&dst->lock, flags);
 
         /*
-         * Make the list addition visible before sending the ipi.
+         * The list addition should be visible before sending the IPI
+         * handler locks the list to pull the entry off it because of
+         * normal cache coherency rules implied by spinlocks.
+         *
+         * If IPIs can go out of order to the cache coherency protocol
+         * in an architecture, sufficient synchronisation should be added
+         * to arch code to make it appear to obey cache coherency WRT
+         * locking and barrier primitives. Generic code isn't really
+         * equipped to do the right thing...
          */
-        smp_mb();
-
         if (ipi)
                 arch_send_call_function_single_ipi(cpu);
 
         if (wait)
-                csd_flag_wait(data);
-}
-
-static void rcu_free_call_data(struct rcu_head *head)
-{
-        struct call_function_data *data;
-
-        data = container_of(head, struct call_function_data, rcu_head);
-
-        kfree(data);
+                csd_lock_wait(data);
 }
 
 /*
@@ -104,99 +177,83 @@ void generic_smp_call_function_interrupt(void)
         int cpu = get_cpu();
 
         /*
-         * It's ok to use list_for_each_rcu() here even though we may delete
-         * 'pos', since list_del_rcu() doesn't clear ->next
+         * Ensure entry is visible on call_function_queue after we have
+         * entered the IPI. See comment in smp_call_function_many.
+         * If we don't have this, then we may miss an entry on the list
+         * and never get another IPI to process it.
+         */
+        smp_mb();
+
+        /*
+         * It's ok to use list_for_each_rcu() here even though we may
+         * delete 'pos', since list_del_rcu() doesn't clear ->next
          */
-        rcu_read_lock();
-        list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
+        list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
                 int refs;
 
-                if (!cpumask_test_cpu(cpu, to_cpumask(data->cpumask_bits)))
+                spin_lock(&data->lock);
+                if (!cpumask_test_cpu(cpu, data->cpumask)) {
+                        spin_unlock(&data->lock);
                         continue;
+                }
+                cpumask_clear_cpu(cpu, data->cpumask);
+                spin_unlock(&data->lock);
 
                 data->csd.func(data->csd.info);
 
                 spin_lock(&data->lock);
-                cpumask_clear_cpu(cpu, to_cpumask(data->cpumask_bits));
                 WARN_ON(data->refs == 0);
-                data->refs--;
-                refs = data->refs;
+                refs = --data->refs;
+                if (!refs) {
+                        spin_lock(&call_function.lock);
+                        list_del_rcu(&data->csd.list);
+                        spin_unlock(&call_function.lock);
+                }
                 spin_unlock(&data->lock);
 
                 if (refs)
                         continue;
 
-                spin_lock(&call_function_lock);
-                list_del_rcu(&data->csd.list);
-                spin_unlock(&call_function_lock);
-
-                if (data->csd.flags & CSD_FLAG_WAIT) {
-                        /*
-                         * serialize stores to data with the flag clear
-                         * and wakeup
-                         */
-                        smp_wmb();
-                        data->csd.flags &= ~CSD_FLAG_WAIT;
-                }
-                if (data->csd.flags & CSD_FLAG_ALLOC)
-                        call_rcu(&data->rcu_head, rcu_free_call_data);
+                csd_unlock(&data->csd);
         }
-        rcu_read_unlock();
 
         put_cpu();
 }
 
 /*
- * Invoked by arch to handle an IPI for call function single. Must be called
- * from the arch with interrupts disabled.
+ * Invoked by arch to handle an IPI for call function single. Must be
+ * called from the arch with interrupts disabled.
  */
 void generic_smp_call_function_single_interrupt(void)
 {
         struct call_single_queue *q = &__get_cpu_var(call_single_queue);
+        unsigned int data_flags;
         LIST_HEAD(list);
 
-        /*
-         * Need to see other stores to list head for checking whether
-         * list is empty without holding q->lock
-         */
-        smp_read_barrier_depends();
-        while (!list_empty(&q->list)) {
-                unsigned int data_flags;
-
-                spin_lock(&q->lock);
-                list_replace_init(&q->list, &list);
-                spin_unlock(&q->lock);
-
-                while (!list_empty(&list)) {
-                        struct call_single_data *data;
-
-                        data = list_entry(list.next, struct call_single_data,
-                                                list);
-                        list_del(&data->list);
-
-                        /*
-                         * 'data' can be invalid after this call if
-                         * flags == 0 (when called through
-                         * generic_exec_single(), so save them away before
-                         * making the call.
-                         */
-                        data_flags = data->flags;
-
-                        data->func(data->info);
-
-                        if (data_flags & CSD_FLAG_WAIT) {
-                                smp_wmb();
-                                data->flags &= ~CSD_FLAG_WAIT;
-                        } else if (data_flags & CSD_FLAG_LOCK) {
-                                smp_wmb();
-                                data->flags &= ~CSD_FLAG_LOCK;
-                        } else if (data_flags & CSD_FLAG_ALLOC)
-                                kfree(data);
-                }
+        spin_lock(&q->lock);
+        list_replace_init(&q->list, &list);
+        spin_unlock(&q->lock);
+
+        while (!list_empty(&list)) {
+                struct call_single_data *data;
+
+                data = list_entry(list.next, struct call_single_data, list);
+                list_del(&data->list);
+
+                /*
+                 * 'data' can be invalid after this call if flags == 0
+                 * (when called through generic_exec_single()),
+                 * so save them away before making the call:
+                 */
+                data_flags = data->flags;
+
+                data->func(data->info);
+
                 /*
-                 * See comment on outer loop
+                 * Unlocked CSDs are valid through generic_exec_single():
                  */
-                smp_read_barrier_depends();
+                if (data_flags & CSD_FLAG_LOCK)
+                        csd_unlock(data);
         }
 }
 
@@ -215,65 +272,45 @@ static DEFINE_PER_CPU(struct call_single_data, csd_data);
 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
                              int wait)
 {
-        struct call_single_data d;
+        struct call_single_data d = {
+                .flags = 0,
+        };
         unsigned long flags;
-        /* prevent preemption and reschedule on another processor,
-           as well as CPU removal */
-        int me = get_cpu();
+        int this_cpu;
         int err = 0;
 
+        /*
+         * prevent preemption and reschedule on another processor,
+         * as well as CPU removal
+         */
+        this_cpu = get_cpu();
+
         /* Can deadlock when called with interrupts disabled */
-        WARN_ON(irqs_disabled());
+        WARN_ON_ONCE(irqs_disabled() && !oops_in_progress);
 
-        if (cpu == me) {
+        if (cpu == this_cpu) {
                 local_irq_save(flags);
                 func(info);
                 local_irq_restore(flags);
-        } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
-                struct call_single_data *data;
+        } else {
+                if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
+                        struct call_single_data *data = &d;
+
+                        if (!wait)
+                                data = &__get_cpu_var(csd_data);
 
-                if (!wait) {
-                        /*
-                         * We are calling a function on a single CPU
-                         * and we are not going to wait for it to finish.
-                         * We first try to allocate the data, but if we
-                         * fail, we fall back to use a per cpu data to pass
-                         * the information to that CPU. Since all callers
-                         * of this code will use the same data, we must
-                         * synchronize the callers to prevent a new caller
-                         * from corrupting the data before the callee
-                         * can access it.
-                         *
-                         * The CSD_FLAG_LOCK is used to let us know when
-                         * the IPI handler is done with the data.
-                         * The first caller will set it, and the callee
-                         * will clear it. The next caller must wait for
-                         * it to clear before we set it again. This
-                         * will make sure the callee is done with the
-                         * data before a new caller will use it.
-                         */
-                        data = kmalloc(sizeof(*data), GFP_ATOMIC);
-                        if (data)
-                                data->flags = CSD_FLAG_ALLOC;
-                        else {
-                                data = &per_cpu(csd_data, me);
-                                while (data->flags & CSD_FLAG_LOCK)
-                                        cpu_relax();
-                                data->flags = CSD_FLAG_LOCK;
-                        }
+                        csd_lock(data);
+
+                        data->func = func;
+                        data->info = info;
+                        generic_exec_single(cpu, data, wait);
                 } else {
-                        data = &d;
-                        data->flags = CSD_FLAG_WAIT;
+                        err = -ENXIO;   /* CPU not online */
                 }
-
-                data->func = func;
-                data->info = info;
-                generic_exec_single(cpu, data);
-        } else {
-                err = -ENXIO;   /* CPU not online */
         }
 
         put_cpu();
+
         return err;
 }
 EXPORT_SYMBOL(smp_call_function_single);
@@ -283,23 +320,26 @@ EXPORT_SYMBOL(smp_call_function_single);
  * @cpu: The CPU to run on.
  * @data: Pre-allocated and setup data structure
  *
- * Like smp_call_function_single(), but allow caller to pass in a pre-allocated
- * data structure. Useful for embedding @data inside other structures, for
- * instance.
- *
+ * Like smp_call_function_single(), but allow caller to pass in a
+ * pre-allocated data structure. Useful for embedding @data inside
+ * other structures, for instance.
  */
-void __smp_call_function_single(int cpu, struct call_single_data *data)
+void __smp_call_function_single(int cpu, struct call_single_data *data,
+                                int wait)
 {
+        csd_lock(data);
+
         /* Can deadlock when called with interrupts disabled */
-        WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
+        WARN_ON_ONCE(wait && irqs_disabled() && !oops_in_progress);
 
-        generic_exec_single(cpu, data);
+        generic_exec_single(cpu, data, wait);
 }
 
-/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
+/* Deprecated: shim for archs using old arch_send_call_function_ipi API. */
+
 #ifndef arch_send_call_function_ipi_mask
-#define arch_send_call_function_ipi_mask(maskp) \
-        arch_send_call_function_ipi(*(maskp))
+# define arch_send_call_function_ipi_mask(maskp) \
+         arch_send_call_function_ipi(*(maskp))
 #endif
 
 /**
@@ -307,7 +347,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
  * @mask: The set of cpus to run on (only runs on online subset).
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
  *
  * If @wait is true, then returns once @func has returned. Note that @wait
  * will be implicitly turned on in case of allocation failures, since
@@ -318,27 +359,27 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
  * must be disabled when calling this function.
  */
 void smp_call_function_many(const struct cpumask *mask,
-                            void (*func)(void *), void *info,
-                            bool wait)
+                            void (*func)(void *), void *info, bool wait)
 {
         struct call_function_data *data;
         unsigned long flags;
-        int cpu, next_cpu;
+        int cpu, next_cpu, this_cpu = smp_processor_id();
 
         /* Can deadlock when called with interrupts disabled */
-        WARN_ON(irqs_disabled());
+        WARN_ON_ONCE(irqs_disabled() && !oops_in_progress);
 
-        /* So, what's a CPU they want?  Ignoring this one. */
+        /* So, what's a CPU they want? Ignoring this one. */
         cpu = cpumask_first_and(mask, cpu_online_mask);
-        if (cpu == smp_processor_id())
+        if (cpu == this_cpu)
                 cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+
         /* No online cpus?  We're done. */
         if (cpu >= nr_cpu_ids)
                 return;
 
         /* Do we have another CPU which isn't us? */
         next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
-        if (next_cpu == smp_processor_id())
+        if (next_cpu == this_cpu)
                 next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
 
         /* Fastpath: do that cpu by itself. */
@@ -347,43 +388,40 @@ void smp_call_function_many(const struct cpumask *mask,
                 return;
         }
 
-        data = kmalloc(sizeof(*data) + cpumask_size(), GFP_ATOMIC);
-        if (unlikely(!data)) {
-                /* Slow path. */
-                for_each_online_cpu(cpu) {
-                        if (cpu == smp_processor_id())
-                                continue;
-                        if (cpumask_test_cpu(cpu, mask))
-                                smp_call_function_single(cpu, func, info, wait);
-                }
-                return;
-        }
+        data = &__get_cpu_var(cfd_data);
+        csd_lock(&data->csd);
 
-        spin_lock_init(&data->lock);
-        data->csd.flags = CSD_FLAG_ALLOC;
-        if (wait)
-                data->csd.flags |= CSD_FLAG_WAIT;
+        spin_lock_irqsave(&data->lock, flags);
         data->csd.func = func;
         data->csd.info = info;
-        cpumask_and(to_cpumask(data->cpumask_bits), mask, cpu_online_mask);
-        cpumask_clear_cpu(smp_processor_id(), to_cpumask(data->cpumask_bits));
-        data->refs = cpumask_weight(to_cpumask(data->cpumask_bits));
+        cpumask_and(data->cpumask, mask, cpu_online_mask);
+        cpumask_clear_cpu(this_cpu, data->cpumask);
+        data->refs = cpumask_weight(data->cpumask);
 
-        spin_lock_irqsave(&call_function_lock, flags);
-        list_add_tail_rcu(&data->csd.list, &call_function_queue);
-        spin_unlock_irqrestore(&call_function_lock, flags);
+        spin_lock(&call_function.lock);
+        /*
+         * Place entry at the _HEAD_ of the list, so that any cpu still
+         * observing the entry in generic_smp_call_function_interrupt()
+         * will not miss any other list entries:
+         */
+        list_add_rcu(&data->csd.list, &call_function.queue);
+        spin_unlock(&call_function.lock);
+
+        spin_unlock_irqrestore(&data->lock, flags);
 
         /*
          * Make the list addition visible before sending the ipi.
+         * (IPIs must obey or appear to obey normal Linux cache
+         * coherency rules -- see comment in generic_exec_single).
          */
         smp_mb();
 
         /* Send a message to all CPUs in the map */
-        arch_send_call_function_ipi_mask(to_cpumask(data->cpumask_bits));
+        arch_send_call_function_ipi_mask(data->cpumask);
 
-        /* optionally wait for the CPUs to complete */
+        /* Optionally wait for the CPUs to complete */
         if (wait)
-                csd_flag_wait(&data->csd);
+                csd_lock_wait(&data->csd);
 }
 EXPORT_SYMBOL(smp_call_function_many);
 
@@ -391,7 +429,8 @@ EXPORT_SYMBOL(smp_call_function_many);
  * smp_call_function(): Run a function on all other CPUs.
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
  *
  * Returns 0.
  *
@@ -407,26 +446,27 @@ int smp_call_function(void (*func)(void *), void *info, int wait)
         preempt_disable();
         smp_call_function_many(cpu_online_mask, func, info, wait);
         preempt_enable();
+
         return 0;
 }
 EXPORT_SYMBOL(smp_call_function);
 
 void ipi_call_lock(void)
 {
-        spin_lock(&call_function_lock);
+        spin_lock(&call_function.lock);
 }
 
 void ipi_call_unlock(void)
 {
-        spin_unlock(&call_function_lock);
+        spin_unlock(&call_function.lock);
 }
 
 void ipi_call_lock_irq(void)
 {
-        spin_lock_irq(&call_function_lock);
+        spin_lock_irq(&call_function.lock);
 }
 
 void ipi_call_unlock_irq(void)
 {
-        spin_unlock_irq(&call_function_lock);
+        spin_unlock_irq(&call_function.lock);
 }
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 487751604300..ea23ec087ee9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -496,7 +496,7 @@ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softir
                 cp->flags = 0;
                 cp->priv = softirq;
 
-                __smp_call_function_single(cpu, cp);
+                __smp_call_function_single(cpu, cp, 0);
                 return 0;
         }
         return 1;