[PATCH 4/8] Rip out lock_cpu_hotplug()

From: Gautham R Shenoy
Date: Mon Apr 02 2007 - 01:40:05 EST

This patch rips out lock_cpu_hotplug from the kernel.
Good Riddance!! (hopefully :) )

Signed-off-by : Gautham R Shenoy <ego@xxxxxxxxxx>
--
arch/i386/kernel/cpu/mtrr/main.c | 6 ------
arch/i386/kernel/microcode.c | 8 --------
arch/mips/kernel/mips-mt.c | 5 -----
arch/powerpc/platforms/pseries/hotplug-cpu.c | 5 -----
arch/powerpc/platforms/pseries/rtasd.c | 4 ----
include/linux/cpu.h | 20 --------------------
kernel/cpu.c | 17 -----------------
kernel/rcutorture.c | 3 ---
kernel/stop_machine.c | 3 ---
net/core/flow.c | 2 --
10 files changed, 73 deletions(-)

Index: linux-2.6.21-rc4/include/linux/cpu.h
===================================================================
--- linux-2.6.21-rc4.orig/include/linux/cpu.h
+++ linux-2.6.21-rc4/include/linux/cpu.h
@@ -89,18 +89,6 @@ extern struct sysdev_class cpu_sysdev_cl
#ifdef CONFIG_HOTPLUG_CPU
/* Stop CPUs going up and down. */

-static inline void cpuhotplug_mutex_lock(struct mutex *cpu_hp_mutex)
-{
- mutex_lock(cpu_hp_mutex);
-}
-
-static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
-{
- mutex_unlock(cpu_hp_mutex);
-}
-
-extern void lock_cpu_hotplug(void);
-extern void unlock_cpu_hotplug(void);
#define hotcpu_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
{ .notifier_call = fn, .priority = pri }; \
@@ -113,14 +101,6 @@ int cpu_down(unsigned int cpu);

#else /* CONFIG_HOTPLUG_CPU */

-static inline void cpuhotplug_mutex_lock(struct mutex *cpu_hp_mutex)
-{ }
-static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
-{ }
-
-#define lock_cpu_hotplug() do { } while (0)
-#define unlock_cpu_hotplug() do { } while (0)
-#define lock_cpu_hotplug_interruptible() 0
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
#define register_hotcpu_notifier(nb) do { (void)(nb); } while (0)
#define unregister_hotcpu_notifier(nb) do { (void)(nb); } while (0)
Index: linux-2.6.21-rc4/kernel/cpu.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/cpu.c
+++ linux-2.6.21-rc4/kernel/cpu.c
@@ -18,7 +18,6 @@

/* This protects CPUs going up and down... */
static DEFINE_MUTEX(cpu_add_remove_lock);
-static DEFINE_MUTEX(cpu_bitmask_lock);

static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);

@@ -27,22 +26,6 @@ static __cpuinitdata RAW_NOTIFIER_HEAD(c
*/
static int cpu_hotplug_disabled;

-#ifdef CONFIG_HOTPLUG_CPU
-
-void lock_cpu_hotplug(void)
-{
- return;
-}
-EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
-
-void unlock_cpu_hotplug(void)
-{
- return;
-}
-EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
-
-#endif /* CONFIG_HOTPLUG_CPU */
-
/* Need to know about CPUs going up/down? */
int __cpuinit register_cpu_notifier(struct notifier_block *nb)
{
Index: linux-2.6.21-rc4/arch/i386/kernel/cpu/mtrr/main.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/i386/kernel/cpu/mtrr/main.c
+++ linux-2.6.21-rc4/arch/i386/kernel/cpu/mtrr/main.c
@@ -346,8 +346,6 @@ int mtrr_add_page(unsigned long base, un
error = -EINVAL;
replace = -1;

- /* No CPU hotplug when we change MTRR entries */
- lock_cpu_hotplug();
/* Search for existing MTRR */
mutex_lock(&mtrr_mutex);
for (i = 0; i < num_var_ranges; ++i) {
@@ -403,7 +401,6 @@ int mtrr_add_page(unsigned long base, un
error = i;
out:
mutex_unlock(&mtrr_mutex);
- unlock_cpu_hotplug();
return error;
}

@@ -492,8 +489,6 @@ int mtrr_del_page(int reg, unsigned long
return -ENXIO;

max = num_var_ranges;
- /* No CPU hotplug when we change MTRR entries */
- lock_cpu_hotplug();
mutex_lock(&mtrr_mutex);
if (reg < 0) {
/* Search for existing MTRR */
@@ -534,7 +529,6 @@ int mtrr_del_page(int reg, unsigned long
error = reg;
out:
mutex_unlock(&mtrr_mutex);
- unlock_cpu_hotplug();
return error;
}
/**
Index: linux-2.6.21-rc4/arch/i386/kernel/microcode.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/i386/kernel/microcode.c
+++ linux-2.6.21-rc4/arch/i386/kernel/microcode.c
@@ -435,7 +435,6 @@ static ssize_t microcode_write (struct f
return -EINVAL;
}

- lock_cpu_hotplug();
mutex_lock(&microcode_mutex);

user_buffer = (void __user *) buf;
@@ -446,7 +445,6 @@ static ssize_t microcode_write (struct f
ret = (ssize_t)len;

mutex_unlock(&microcode_mutex);
- unlock_cpu_hotplug();

return ret;
}
@@ -609,14 +607,12 @@ static ssize_t reload_store(struct sys_d

old = current->cpus_allowed;

- lock_cpu_hotplug();
set_cpus_allowed(current, cpumask_of_cpu(cpu));

mutex_lock(&microcode_mutex);
if (uci->valid)
err = cpu_request_microcode(cpu);
mutex_unlock(&microcode_mutex);
- unlock_cpu_hotplug();
set_cpus_allowed(current, old);
}
if (err)
@@ -740,9 +736,7 @@ static int __init microcode_init (void)
return PTR_ERR(microcode_pdev);
}

- lock_cpu_hotplug();
error = sysdev_driver_register(&cpu_sysdev_class, &mc_sysdev_driver);
- unlock_cpu_hotplug();
if (error) {
microcode_dev_exit();
platform_device_unregister(microcode_pdev);
@@ -762,9 +756,7 @@ static void __exit microcode_exit (void)

unregister_hotcpu_notifier(&mc_cpu_notifier);

- lock_cpu_hotplug();
sysdev_driver_unregister(&cpu_sysdev_class, &mc_sysdev_driver);
- unlock_cpu_hotplug();

platform_device_unregister(microcode_pdev);
}
Index: linux-2.6.21-rc4/arch/mips/kernel/mips-mt.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/mips/kernel/mips-mt.c
+++ linux-2.6.21-rc4/arch/mips/kernel/mips-mt.c
@@ -73,13 +73,11 @@ asmlinkage long mipsmt_sys_sched_setaffi
if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
return -EFAULT;

- lock_cpu_hotplug();
read_lock(&tasklist_lock);

p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
- unlock_cpu_hotplug();
return -ESRCH;
}

@@ -121,7 +119,6 @@ asmlinkage long mipsmt_sys_sched_setaffi

out_unlock:
put_task_struct(p);
- unlock_cpu_hotplug();
return retval;
}

@@ -140,7 +137,6 @@ asmlinkage long mipsmt_sys_sched_getaffi
if (len < real_len)
return -EINVAL;

- lock_cpu_hotplug();
read_lock(&tasklist_lock);

retval = -ESRCH;
@@ -155,7 +151,6 @@ asmlinkage long mipsmt_sys_sched_getaffi

out_unlock:
read_unlock(&tasklist_lock);
- unlock_cpu_hotplug();
if (retval)
return retval;
if (copy_to_user(user_mask_ptr, &mask, real_len))
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hotplug-cpu.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -151,8 +151,6 @@ static int pseries_add_processor(struct
for (i = 0; i < nthreads; i++)
cpu_set(i, tmp);

- lock_cpu_hotplug();
-
BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));

/* Get a bitmap of unoccupied slots. */
@@ -188,7 +186,6 @@ static int pseries_add_processor(struct
}
err = 0;
out_unlock:
- unlock_cpu_hotplug();
return err;
}

@@ -209,7 +206,6 @@ static void pseries_remove_processor(str

nthreads = len / sizeof(u32);

- lock_cpu_hotplug();
for (i = 0; i < nthreads; i++) {
for_each_present_cpu(cpu) {
if (get_hard_smp_processor_id(cpu) != intserv[i])
@@ -223,7 +219,6 @@ static void pseries_remove_processor(str
printk(KERN_WARNING "Could not find cpu to remove "
"with physical id 0x%x\n", intserv[i]);
}
- unlock_cpu_hotplug();
}

static int pseries_smp_notifier(struct notifier_block *nb,
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/rtasd.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/rtasd.c
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/rtasd.c
@@ -404,7 +404,6 @@ static void do_event_scan_all_cpus(long
{
int cpu;

- lock_cpu_hotplug();
cpu = first_cpu(cpu_online_map);
for (;;) {
set_cpus_allowed(current, cpumask_of_cpu(cpu));
@@ -412,15 +411,12 @@ static void do_event_scan_all_cpus(long
set_cpus_allowed(current, CPU_MASK_ALL);

/* Drop hotplug lock, and sleep for the specified delay */
- unlock_cpu_hotplug();
msleep_interruptible(delay);
- lock_cpu_hotplug();

cpu = next_cpu(cpu, cpu_online_map);
if (cpu == NR_CPUS)
break;
}
- unlock_cpu_hotplug();
}

static int rtasd(void *unused)
Index: linux-2.6.21-rc4/kernel/rcutorture.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/rcutorture.c
+++ linux-2.6.21-rc4/kernel/rcutorture.c
@@ -733,11 +733,9 @@ static void rcu_torture_shuffle_tasks(vo
cpumask_t tmp_mask = CPU_MASK_ALL;
int i;

- lock_cpu_hotplug();

/* No point in shuffling if there is only one online CPU (ex: UP) */
if (num_online_cpus() == 1) {
- unlock_cpu_hotplug();
return;
}

@@ -769,7 +767,6 @@ static void rcu_torture_shuffle_tasks(vo
else
rcu_idle_cpu--;

- unlock_cpu_hotplug();
}

/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
Index: linux-2.6.21-rc4/kernel/stop_machine.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/stop_machine.c
+++ linux-2.6.21-rc4/kernel/stop_machine.c
@@ -198,14 +198,11 @@ int stop_machine_run(int (*fn)(void *),
struct task_struct *p;
int ret;

- /* No CPUs can come up or down during this. */
- lock_cpu_hotplug();
p = __stop_machine_run(fn, data, cpu);
if (!IS_ERR(p))
ret = kthread_stop(p);
else
ret = PTR_ERR(p);
- unlock_cpu_hotplug();

return ret;
}
Index: linux-2.6.21-rc4/net/core/flow.c
===================================================================
--- linux-2.6.21-rc4.orig/net/core/flow.c
+++ linux-2.6.21-rc4/net/core/flow.c
@@ -296,7 +296,6 @@ void flow_cache_flush(void)
static DEFINE_MUTEX(flow_flush_sem);

/* Don't want cpus going down or up during this. */
- lock_cpu_hotplug();
mutex_lock(&flow_flush_sem);
atomic_set(&info.cpuleft, num_online_cpus());
init_completion(&info.completion);
@@ -308,7 +307,6 @@ void flow_cache_flush(void)

wait_for_completion(&info.completion);
mutex_unlock(&flow_flush_sem);
- unlock_cpu_hotplug();
}

static void __devinit flow_cache_cpu_prepare(int cpu)
--
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
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