[GIT PULL] core/locking changes for v3.1

[GIT PULL] core/locking changes for v3.1

[Ingo Molnar]

Linus,

Please pull the latest core-locking-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core-locking-for-linus

 Thanks,

	Ingo

------------------>
Anton Blanchard (1):
      lockup detector: Fix reference to the non-existent CONFIG_DETECT_SOFTLOCKUP option

Dima Zavin (1):
      plist: Remove the need to supply locks to plist heads

Jean Delvare (1):
      mutex: Make mutex_destroy() an inline function

Peter Zijlstra (1):
      lockdep: Fix lockdep_no_validate against IRQ states


 include/linux/mutex.h   |    2 +-
 include/linux/plist.h   |   55 ++--------------------------------------------
 include/linux/rtmutex.h |    4 +-
 kernel/fork.c           |    2 +-
 kernel/futex.c          |    2 +-
 kernel/lockdep.c        |    3 ++
 kernel/pm_qos_params.c  |    6 ++--
 kernel/rtmutex.c        |    2 +-
 kernel/sched.c          |    4 +-
 lib/Kconfig.debug       |    4 +-
 lib/plist.c             |    7 +-----
 11 files changed, 20 insertions(+), 71 deletions(-)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index a940fe4..7f87217 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -92,7 +92,7 @@ do {							\
 							\
 	__mutex_init((mutex), #mutex, &__key);		\
 } while (0)
-# define mutex_destroy(mutex)				do { } while (0)
+static inline void mutex_destroy(struct mutex *lock) {}
 #endif
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
diff --git a/include/linux/plist.h b/include/linux/plist.h
index c9b9f32..aa0fb39 100644
--- a/include/linux/plist.h
+++ b/include/linux/plist.h
@@ -77,14 +77,9 @@
 
 #include <linux/kernel.h>
 #include <linux/list.h>
-#include <linux/spinlock_types.h>
 
 struct plist_head {
 	struct list_head node_list;
-#ifdef CONFIG_DEBUG_PI_LIST
-	raw_spinlock_t *rawlock;
-	spinlock_t *spinlock;
-#endif
 };
 
 struct plist_node {
@@ -93,37 +88,13 @@ struct plist_node {
 	struct list_head	node_list;
 };
 
-#ifdef CONFIG_DEBUG_PI_LIST
-# define PLIST_HEAD_LOCK_INIT(_lock)		.spinlock = _lock
-# define PLIST_HEAD_LOCK_INIT_RAW(_lock)	.rawlock = _lock
-#else
-# define PLIST_HEAD_LOCK_INIT(_lock)
-# define PLIST_HEAD_LOCK_INIT_RAW(_lock)
-#endif
-
-#define _PLIST_HEAD_INIT(head)				\
-	.node_list = LIST_HEAD_INIT((head).node_list)
-
 /**
  * PLIST_HEAD_INIT - static struct plist_head initializer
  * @head:	struct plist_head variable name
- * @_lock:	lock to initialize for this list
- */
-#define PLIST_HEAD_INIT(head, _lock)			\
-{							\
-	_PLIST_HEAD_INIT(head),				\
-	PLIST_HEAD_LOCK_INIT(&(_lock))			\
-}
-
-/**
- * PLIST_HEAD_INIT_RAW - static struct plist_head initializer
- * @head:	struct plist_head variable name
- * @_lock:	lock to initialize for this list
  */
-#define PLIST_HEAD_INIT_RAW(head, _lock)		\
+#define PLIST_HEAD_INIT(head)				\
 {							\
-	_PLIST_HEAD_INIT(head),				\
-	PLIST_HEAD_LOCK_INIT_RAW(&(_lock))		\
+	.node_list = LIST_HEAD_INIT((head).node_list)	\
 }
 
 /**
@@ -141,31 +112,11 @@ struct plist_node {
 /**
  * plist_head_init - dynamic struct plist_head initializer
  * @head:	&struct plist_head pointer
- * @lock:	spinlock protecting the list (debugging)
  */
 static inline void
-plist_head_init(struct plist_head *head, spinlock_t *lock)
+plist_head_init(struct plist_head *head)
 {
 	INIT_LIST_HEAD(&head->node_list);
-#ifdef CONFIG_DEBUG_PI_LIST
-	head->spinlock = lock;
-	head->rawlock = NULL;
-#endif
-}
-
-/**
- * plist_head_init_raw - dynamic struct plist_head initializer
- * @head:	&struct plist_head pointer
- * @lock:	raw_spinlock protecting the list (debugging)
- */
-static inline void
-plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
-{
-	INIT_LIST_HEAD(&head->node_list);
-#ifdef CONFIG_DEBUG_PI_LIST
-	head->rawlock = lock;
-	head->spinlock = NULL;
-#endif
 }
 
 /**
diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index 8d522ff..de17134 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -66,7 +66,7 @@ struct hrtimer_sleeper;
 
 #define __RT_MUTEX_INITIALIZER(mutexname) \
 	{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
-	, .wait_list = PLIST_HEAD_INIT_RAW(mutexname.wait_list, mutexname.wait_lock) \
+	, .wait_list = PLIST_HEAD_INIT(mutexname.wait_list) \
 	, .owner = NULL \
 	__DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
 
@@ -100,7 +100,7 @@ extern void rt_mutex_unlock(struct rt_mutex *lock);
 
 #ifdef CONFIG_RT_MUTEXES
 # define INIT_RT_MUTEXES(tsk)						\
-	.pi_waiters	= PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock),	\
+	.pi_waiters	= PLIST_HEAD_INIT(tsk.pi_waiters),	\
 	INIT_RT_MUTEX_DEBUG(tsk)
 #else
 # define INIT_RT_MUTEXES(tsk)
diff --git a/kernel/fork.c b/kernel/fork.c
index 0276c30..7517a53 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1013,7 +1013,7 @@ static void rt_mutex_init_task(struct task_struct *p)
 {
 	raw_spin_lock_init(&p->pi_lock);
 #ifdef CONFIG_RT_MUTEXES
-	plist_head_init_raw(&p->pi_waiters, &p->pi_lock);
+	plist_head_init(&p->pi_waiters);
 	p->pi_blocked_on = NULL;
 #endif
 }
diff --git a/kernel/futex.c b/kernel/futex.c
index fe28dc2..3fbc76c 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2697,7 +2697,7 @@ static int __init futex_init(void)
 		futex_cmpxchg_enabled = 1;
 
 	for (i = 0; i < ARRAY_SIZE(futex_queues); i++) {
-		plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock);
+		plist_head_init(&futex_queues[i].chain);
 		spin_lock_init(&futex_queues[i].lock);
 	}
 
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 298c927..628276d 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2468,6 +2468,9 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
 
 		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
 
+		if (hlock_class(hlock)->key == &__lockdep_no_validate__)
+			continue;
+
 		if (!mark_lock(curr, hlock, usage_bit))
 			return 0;
 	}
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index 6824ca7..37f05d0 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -74,7 +74,7 @@ static DEFINE_SPINLOCK(pm_qos_lock);
 static struct pm_qos_object null_pm_qos;
 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
 static struct pm_qos_object cpu_dma_pm_qos = {
-	.requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
+	.requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests),
 	.notifiers = &cpu_dma_lat_notifier,
 	.name = "cpu_dma_latency",
 	.target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
@@ -84,7 +84,7 @@ static struct pm_qos_object cpu_dma_pm_qos = {
 
 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
 static struct pm_qos_object network_lat_pm_qos = {
-	.requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
+	.requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests),
 	.notifiers = &network_lat_notifier,
 	.name = "network_latency",
 	.target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
@@ -95,7 +95,7 @@ static struct pm_qos_object network_lat_pm_qos = {
 
 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
 static struct pm_qos_object network_throughput_pm_qos = {
-	.requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
+	.requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests),
 	.notifiers = &network_throughput_notifier,
 	.name = "network_throughput",
 	.target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index ab44911..255e166 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -890,7 +890,7 @@ void __rt_mutex_init(struct rt_mutex *lock, const char *name)
 {
 	lock->owner = NULL;
 	raw_spin_lock_init(&lock->wait_lock);
-	plist_head_init_raw(&lock->wait_list, &lock->wait_lock);
+	plist_head_init(&lock->wait_list);
 
 	debug_rt_mutex_init(lock, name);
 }
diff --git a/kernel/sched.c b/kernel/sched.c
index 3f2e502..71bc127 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7781,7 +7781,7 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
 #ifdef CONFIG_SMP
 	rt_rq->rt_nr_migratory = 0;
 	rt_rq->overloaded = 0;
-	plist_head_init_raw(&rt_rq->pushable_tasks, &rq->lock);
+	plist_head_init(&rt_rq->pushable_tasks);
 #endif
 
 	rt_rq->rt_time = 0;
@@ -7986,7 +7986,7 @@ void __init sched_init(void)
 #endif
 
 #ifdef CONFIG_RT_MUTEXES
-	plist_head_init_raw(&init_task.pi_waiters, &init_task.pi_lock);
+	plist_head_init(&init_task.pi_waiters);
 #endif
 
 	/*
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index dd373c8..9c28fa4 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -227,7 +227,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 config DETECT_HUNG_TASK
 	bool "Detect Hung Tasks"
 	depends on DEBUG_KERNEL
-	default DETECT_SOFTLOCKUP
+	default LOCKUP_DETECTOR
 	help
 	  Say Y here to enable the kernel to detect "hung tasks",
 	  which are bugs that cause the task to be stuck in
@@ -866,7 +866,7 @@ config BOOT_PRINTK_DELAY
 	  system, and then set "lpj=M" before setting "boot_delay=N".
 	  NOTE:  Using this option may adversely affect SMP systems.
 	  I.e., processors other than the first one may not boot up.
-	  BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
+	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 	  what it believes to be lockup conditions.
 
 config RCU_TORTURE_TEST
diff --git a/lib/plist.c b/lib/plist.c
index 0ae7e64..a0a4da4 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -56,11 +56,6 @@ static void plist_check_list(struct list_head *top)
 
 static void plist_check_head(struct plist_head *head)
 {
-	WARN_ON(head != &test_head && !head->rawlock && !head->spinlock);
-	if (head->rawlock)
-		WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
-	if (head->spinlock)
-		WARN_ON_SMP(!spin_is_locked(head->spinlock));
 	if (!plist_head_empty(head))
 		plist_check_list(&plist_first(head)->prio_list);
 	plist_check_list(&head->node_list);
@@ -180,7 +175,7 @@ static int  __init plist_test(void)
 	unsigned int r = local_clock();
 
 	printk(KERN_INFO "start plist test\n");
-	plist_head_init(&test_head, NULL);
+	plist_head_init(&test_head);
 	for (i = 0; i < ARRAY_SIZE(test_node); i++)
 		plist_node_init(test_node + i, 0);
 

Re: [GIT PULL] core/locking changes for v3.1

[Arnaud Lacombe]

Hi,

On Fri, Jul 22, 2011 at 8:52 AM, Ingo Molnar <mingo@elte.hu> wrote:
> Linus,
>
> Please pull the latest core-locking-for-linus git tree from:
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core-locking-for-linus
>
>  Thanks,
>
>        Ingo
>
> ------------------>
> Anton Blanchard (1):
>      lockup detector: Fix reference to the non-existent CONFIG_DETECT_SOFTLOCKUP option
>
> Dima Zavin (1):
>      plist: Remove the need to supply locks to plist heads
>
> Jean Delvare (1):
>      mutex: Make mutex_destroy() an inline function
>
> Peter Zijlstra (1):
>      lockdep: Fix lockdep_no_validate against IRQ states
>
from today's master, this last commit triggers:

/src/linux/linux/kernel/lockdep.c: In function 'mark_held_locks':
/src/linux/linux/kernel/lockdep.c:2471:31: warning: comparison of
distinct pointer types lacks a cast

I'm not sure if both struct member and variable's type are correct nor
the comparability between `struct lockdep_subclass_key *' and `struct
lock_class_key *'. So I'll let you fix this.

 - Arnaud

>
>  include/linux/mutex.h   |    2 +-
>  include/linux/plist.h   |   55 ++--------------------------------------------
>  include/linux/rtmutex.h |    4 +-
>  kernel/fork.c           |    2 +-
>  kernel/futex.c          |    2 +-
>  kernel/lockdep.c        |    3 ++
>  kernel/pm_qos_params.c  |    6 ++--
>  kernel/rtmutex.c        |    2 +-
>  kernel/sched.c          |    4 +-
>  lib/Kconfig.debug       |    4 +-
>  lib/plist.c             |    7 +-----
>  11 files changed, 20 insertions(+), 71 deletions(-)
>
> diff --git a/include/linux/mutex.h b/include/linux/mutex.h
> index a940fe4..7f87217 100644
> --- a/include/linux/mutex.h
> +++ b/include/linux/mutex.h
> @@ -92,7 +92,7 @@ do {                                                  \
>                                                        \
>        __mutex_init((mutex), #mutex, &__key);          \
>  } while (0)
> -# define mutex_destroy(mutex)                          do { } while (0)
> +static inline void mutex_destroy(struct mutex *lock) {}
>  #endif
>
>  #ifdef CONFIG_DEBUG_LOCK_ALLOC
> diff --git a/include/linux/plist.h b/include/linux/plist.h
> index c9b9f32..aa0fb39 100644
> --- a/include/linux/plist.h
> +++ b/include/linux/plist.h
> @@ -77,14 +77,9 @@
>
>  #include <linux/kernel.h>
>  #include <linux/list.h>
> -#include <linux/spinlock_types.h>
>
>  struct plist_head {
>        struct list_head node_list;
> -#ifdef CONFIG_DEBUG_PI_LIST
> -       raw_spinlock_t *rawlock;
> -       spinlock_t *spinlock;
> -#endif
>  };
>
>  struct plist_node {
> @@ -93,37 +88,13 @@ struct plist_node {
>        struct list_head        node_list;
>  };
>
> -#ifdef CONFIG_DEBUG_PI_LIST
> -# define PLIST_HEAD_LOCK_INIT(_lock)           .spinlock = _lock
> -# define PLIST_HEAD_LOCK_INIT_RAW(_lock)       .rawlock = _lock
> -#else
> -# define PLIST_HEAD_LOCK_INIT(_lock)
> -# define PLIST_HEAD_LOCK_INIT_RAW(_lock)
> -#endif
> -
> -#define _PLIST_HEAD_INIT(head)                         \
> -       .node_list = LIST_HEAD_INIT((head).node_list)
> -
>  /**
>  * PLIST_HEAD_INIT - static struct plist_head initializer
>  * @head:      struct plist_head variable name
> - * @_lock:     lock to initialize for this list
> - */
> -#define PLIST_HEAD_INIT(head, _lock)                   \
> -{                                                      \
> -       _PLIST_HEAD_INIT(head),                         \
> -       PLIST_HEAD_LOCK_INIT(&(_lock))                  \
> -}
> -
> -/**
> - * PLIST_HEAD_INIT_RAW - static struct plist_head initializer
> - * @head:      struct plist_head variable name
> - * @_lock:     lock to initialize for this list
>  */
> -#define PLIST_HEAD_INIT_RAW(head, _lock)               \
> +#define PLIST_HEAD_INIT(head)                          \
>  {                                                      \
> -       _PLIST_HEAD_INIT(head),                         \
> -       PLIST_HEAD_LOCK_INIT_RAW(&(_lock))              \
> +       .node_list = LIST_HEAD_INIT((head).node_list)   \
>  }
>
>  /**
> @@ -141,31 +112,11 @@ struct plist_node {
>  /**
>  * plist_head_init - dynamic struct plist_head initializer
>  * @head:      &struct plist_head pointer
> - * @lock:      spinlock protecting the list (debugging)
>  */
>  static inline void
> -plist_head_init(struct plist_head *head, spinlock_t *lock)
> +plist_head_init(struct plist_head *head)
>  {
>        INIT_LIST_HEAD(&head->node_list);
> -#ifdef CONFIG_DEBUG_PI_LIST
> -       head->spinlock = lock;
> -       head->rawlock = NULL;
> -#endif
> -}
> -
> -/**
> - * plist_head_init_raw - dynamic struct plist_head initializer
> - * @head:      &struct plist_head pointer
> - * @lock:      raw_spinlock protecting the list (debugging)
> - */
> -static inline void
> -plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
> -{
> -       INIT_LIST_HEAD(&head->node_list);
> -#ifdef CONFIG_DEBUG_PI_LIST
> -       head->rawlock = lock;
> -       head->spinlock = NULL;
> -#endif
>  }
>
>  /**
> diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
> index 8d522ff..de17134 100644
> --- a/include/linux/rtmutex.h
> +++ b/include/linux/rtmutex.h
> @@ -66,7 +66,7 @@ struct hrtimer_sleeper;
>
>  #define __RT_MUTEX_INITIALIZER(mutexname) \
>        { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
> -       , .wait_list = PLIST_HEAD_INIT_RAW(mutexname.wait_list, mutexname.wait_lock) \
> +       , .wait_list = PLIST_HEAD_INIT(mutexname.wait_list) \
>        , .owner = NULL \
>        __DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
>
> @@ -100,7 +100,7 @@ extern void rt_mutex_unlock(struct rt_mutex *lock);
>
>  #ifdef CONFIG_RT_MUTEXES
>  # define INIT_RT_MUTEXES(tsk)                                          \
> -       .pi_waiters     = PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock), \
> +       .pi_waiters     = PLIST_HEAD_INIT(tsk.pi_waiters),      \
>        INIT_RT_MUTEX_DEBUG(tsk)
>  #else
>  # define INIT_RT_MUTEXES(tsk)
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 0276c30..7517a53 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1013,7 +1013,7 @@ static void rt_mutex_init_task(struct task_struct *p)
>  {
>        raw_spin_lock_init(&p->pi_lock);
>  #ifdef CONFIG_RT_MUTEXES
> -       plist_head_init_raw(&p->pi_waiters, &p->pi_lock);
> +       plist_head_init(&p->pi_waiters);
>        p->pi_blocked_on = NULL;
>  #endif
>  }
> diff --git a/kernel/futex.c b/kernel/futex.c
> index fe28dc2..3fbc76c 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -2697,7 +2697,7 @@ static int __init futex_init(void)
>                futex_cmpxchg_enabled = 1;
>
>        for (i = 0; i < ARRAY_SIZE(futex_queues); i++) {
> -               plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock);
> +               plist_head_init(&futex_queues[i].chain);
>                spin_lock_init(&futex_queues[i].lock);
>        }
>
> diff --git a/kernel/lockdep.c b/kernel/lockdep.c
> index 298c927..628276d 100644
> --- a/kernel/lockdep.c
> +++ b/kernel/lockdep.c
> @@ -2468,6 +2468,9 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
>
>                BUG_ON(usage_bit >= LOCK_USAGE_STATES);
>
> +               if (hlock_class(hlock)->key == &__lockdep_no_validate__)
> +                       continue;
> +
>                if (!mark_lock(curr, hlock, usage_bit))
>                        return 0;
>        }
> diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
> index 6824ca7..37f05d0 100644
> --- a/kernel/pm_qos_params.c
> +++ b/kernel/pm_qos_params.c
> @@ -74,7 +74,7 @@ static DEFINE_SPINLOCK(pm_qos_lock);
>  static struct pm_qos_object null_pm_qos;
>  static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
>  static struct pm_qos_object cpu_dma_pm_qos = {
> -       .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
> +       .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests),
>        .notifiers = &cpu_dma_lat_notifier,
>        .name = "cpu_dma_latency",
>        .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
> @@ -84,7 +84,7 @@ static struct pm_qos_object cpu_dma_pm_qos = {
>
>  static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
>  static struct pm_qos_object network_lat_pm_qos = {
> -       .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
> +       .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests),
>        .notifiers = &network_lat_notifier,
>        .name = "network_latency",
>        .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
> @@ -95,7 +95,7 @@ static struct pm_qos_object network_lat_pm_qos = {
>
>  static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
>  static struct pm_qos_object network_throughput_pm_qos = {
> -       .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
> +       .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests),
>        .notifiers = &network_throughput_notifier,
>        .name = "network_throughput",
>        .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
> diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
> index ab44911..255e166 100644
> --- a/kernel/rtmutex.c
> +++ b/kernel/rtmutex.c
> @@ -890,7 +890,7 @@ void __rt_mutex_init(struct rt_mutex *lock, const char *name)
>  {
>        lock->owner = NULL;
>        raw_spin_lock_init(&lock->wait_lock);
> -       plist_head_init_raw(&lock->wait_list, &lock->wait_lock);
> +       plist_head_init(&lock->wait_list);
>
>        debug_rt_mutex_init(lock, name);
>  }
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 3f2e502..71bc127 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -7781,7 +7781,7 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
>  #ifdef CONFIG_SMP
>        rt_rq->rt_nr_migratory = 0;
>        rt_rq->overloaded = 0;
> -       plist_head_init_raw(&rt_rq->pushable_tasks, &rq->lock);
> +       plist_head_init(&rt_rq->pushable_tasks);
>  #endif
>
>        rt_rq->rt_time = 0;
> @@ -7986,7 +7986,7 @@ void __init sched_init(void)
>  #endif
>
>  #ifdef CONFIG_RT_MUTEXES
> -       plist_head_init_raw(&init_task.pi_waiters, &init_task.pi_lock);
> +       plist_head_init(&init_task.pi_waiters);
>  #endif
>
>        /*
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index dd373c8..9c28fa4 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -227,7 +227,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
>  config DETECT_HUNG_TASK
>        bool "Detect Hung Tasks"
>        depends on DEBUG_KERNEL
> -       default DETECT_SOFTLOCKUP
> +       default LOCKUP_DETECTOR
>        help
>          Say Y here to enable the kernel to detect "hung tasks",
>          which are bugs that cause the task to be stuck in
> @@ -866,7 +866,7 @@ config BOOT_PRINTK_DELAY
>          system, and then set "lpj=M" before setting "boot_delay=N".
>          NOTE:  Using this option may adversely affect SMP systems.
>          I.e., processors other than the first one may not boot up.
> -         BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
> +         BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
>          what it believes to be lockup conditions.
>
>  config RCU_TORTURE_TEST
> diff --git a/lib/plist.c b/lib/plist.c
> index 0ae7e64..a0a4da4 100644
> --- a/lib/plist.c
> +++ b/lib/plist.c
> @@ -56,11 +56,6 @@ static void plist_check_list(struct list_head *top)
>
>  static void plist_check_head(struct plist_head *head)
>  {
> -       WARN_ON(head != &test_head && !head->rawlock && !head->spinlock);
> -       if (head->rawlock)
> -               WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
> -       if (head->spinlock)
> -               WARN_ON_SMP(!spin_is_locked(head->spinlock));
>        if (!plist_head_empty(head))
>                plist_check_list(&plist_first(head)->prio_list);
>        plist_check_list(&head->node_list);
> @@ -180,7 +175,7 @@ static int  __init plist_test(void)
>        unsigned int r = local_clock();
>
>        printk(KERN_INFO "start plist test\n");
> -       plist_head_init(&test_head, NULL);
> +       plist_head_init(&test_head);
>        for (i = 0; i < ARRAY_SIZE(test_node); i++)
>                plist_node_init(test_node + i, 0);
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

Re: [GIT PULL] core/locking changes for v3.1

[Peter Zijlstra]

On Sun, 2011-07-24 at 21:06 -0400, Arnaud Lacombe wrote:
> > Peter Zijlstra (1):
> >      lockdep: Fix lockdep_no_validate against IRQ states
> >
> from today's master, this last commit triggers:
> 
> /src/linux/linux/kernel/lockdep.c: In function 'mark_held_locks':
> /src/linux/linux/kernel/lockdep.c:2471:31: warning: comparison of
> distinct pointer types lacks a cast
> 
> I'm not sure if both struct member and variable's type are correct nor
> the comparability between `struct lockdep_subclass_key *' and `struct
> lock_class_key *'. So I'll let you fix this. 

Argh, I really need -Werror to even see warnings, compiler output just
flies by waaaaaay too fast.

The warning is harmless in this case, but the below makes it go away.

---
 kernel/lockdep.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 3956f51..99906aa 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2468,7 +2468,7 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
 
 		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
 
-		if (hlock_class(hlock)->key == &__lockdep_no_validate__)
+		if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
 			continue;
 
 		if (!mark_lock(curr, hlock, usage_bit))

Re: [GIT PULL] core/locking changes for v3.1

[Linus Torvalds]

On Mon, Jul 25, 2011 at 3:09 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> Argh, I really need -Werror to even see warnings, compiler output just
> flies by waaaaaay too fast.

Do what I do:

  make -j32 > ../makes

that way the only thing you see is the warnings (and the final link report).

That pattern was one reason why I wanted me default compile to be
warning-clean. Of course, then gcc started adding more warnings, and
it's not clean any more ("warning: statement with no effect" from the
fact that we just define many functions to '(0)' when they are
disabled) but my current personal compile config only gets four
warnings.

I realize there are *many* more warnings once you start enabling more
special code - as usual, the core code tends to be better quality, and
the further away from that base you get, the worse things get.

But it would definitely be good if most kernel developers did the
above. Do it for just your personal config - at least you'll see the
warnings in code you write (because presumably your personal config
will have that code enabled ;)

                    Linus

Re: [GIT PULL] core/locking changes for v3.1

[Ingo Molnar]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Jul 25, 2011 at 3:09 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> >
> > Argh, I really need -Werror to even see warnings, compiler output just
> > flies by waaaaaay too fast.
> 
> Do what I do:
> 
>   make -j32 > ../makes
> 
> that way the only thing you see is the warnings (and the final link report).
> 
> That pattern was one reason why I wanted me default compile to be 
> warning-clean. Of course, then gcc started adding more warnings, 
> and it's not clean any more ("warning: statement with no effect" 
> from the fact that we just define many functions to '(0)' when they 
> are disabled) but my current personal compile config only gets four 
> warnings.
> 
> I realize there are *many* more warnings once you start enabling 
> more special code - as usual, the core code tends to be better 
> quality, and the further away from that base you get, the worse 
> things get.
> 
> But it would definitely be good if most kernel developers did the 
> above. Do it for just your personal config - at least you'll see 
> the warnings in code you write (because presumably your personal 
> config will have that code enabled ;)

Here is what i see on 'make defconfig' (which enables common core and 
common drivers):

sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_init’:
sound/pci/hda/patch_sigmatel.c:4385:3: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_resume’:
sound/pci/hda/patch_sigmatel.c:4925:3: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc_init’:
sound/pci/hda/patch_realtek.c:4176:2: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc_resume’:
sound/pci/hda/patch_realtek.c:4558:2: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc269_resume’:
sound/pci/hda/patch_realtek.c:14878:2: warning: statement with no 
effect [-Wunused-value]
net/sched/sch_generic.c: In function ‘dev_graft_qdisc’:
net/sched/sch_generic.c:678:2: warning: the comparison will always 
evaluate as ‘true’ for the address of ‘noop_qdisc’ will never be NULL 
[-Waddress]
net/netfilter/nf_conntrack_core.c: In function ‘nf_conntrack_init’:
net/netfilter/nf_conntrack_core.c:1579:3: warning: the comparison 
will always evaluate as ‘true’ for the address of 
‘nf_conntrack_attach’ will never be NULL [-Waddress]
net/netfilter/nf_conntrack_core.c:1580:3: warning: the comparison 
will always evaluate as ‘true’ for the address of ‘destroy_conntrack’ 
will never be NULL [-Waddress]
sound/pci/hda/hda_codec.c: In function 
‘snd_hda_mixer_amp_switch_put’:
sound/pci/hda/hda_codec.c:2320:2: warning: statement with no effect 
[-Wunused-value]
net/netfilter/nf_conntrack_proto.c: In function 
‘nf_conntrack_l3proto_unregister’:
net/netfilter/nf_conntrack_proto.c:210:2: warning: the comparison 
will always evaluate as ‘true’ for the address of 
‘nf_conntrack_l3proto_generic’ will never be NULL [-Waddress]
net/netfilter/nf_conntrack_proto.c: In function 
‘nf_conntrack_l4proto_unregister’:
net/netfilter/nf_conntrack_proto.c:345:2: warning: the comparison 
will always evaluate as ‘true’ for the address of 
‘nf_conntrack_l4proto_generic’ will never be NULL [-Waddress]
net/netfilter/nf_conntrack_proto.c: In function 
‘nf_conntrack_proto_init’:
net/netfilter/nf_conntrack_proto.c:370:3: warning: the comparison 
will always evaluate as ‘true’ for the address of 
‘nf_conntrack_l3proto_generic’ will never be NULL [-Waddress]
drivers/md/dm.c: In function ‘split_bvec’:
drivers/md/dm.c:1052:3: warning: statement with no effect 
[-Wunused-value]
drivers/md/dm.c: In function ‘clone_bio’:
drivers/md/dm.c:1079:3: warning: statement with no effect 
[-Wunused-value]
drivers/md/dm-table.c: In function ‘dm_table_set_integrity’:
drivers/md/dm-table.c:1193:2: warning: statement with no effect 
[-Wunused-value]
net/ipv4/netfilter/nf_nat_standalone.c: In function 
‘nf_nat_standalone_init’:
net/ipv4/netfilter/nf_nat_standalone.c:287:2: warning: the comparison 
will always evaluate as ‘true’ for the address of 
‘nat_decode_session’ will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c: In function 
‘nf_nat_protocol_unregister’:
net/ipv4/netfilter/nf_nat_core.c:528:2: warning: the comparison will 
always evaluate as ‘true’ for the address of 
‘nf_nat_unknown_protocol’ will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c: In function ‘nf_nat_init’:
net/ipv4/netfilter/nf_nat_core.c:739:3: warning: the comparison will 
always evaluate as ‘true’ for the address of 
‘nf_nat_unknown_protocol’ will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:740:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_protocol_tcp’ 
will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:741:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_protocol_udp’ 
will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:742:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_protocol_icmp’ 
will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:751:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_seq_adjust’ will 
never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:753:2: warning: the comparison will 
always evaluate as ‘true’ for the address of 
‘nfnetlink_parse_nat_setup’ will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_core.c:756:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_get_offset’ will 
never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_ftp.c: In function ‘nf_nat_ftp_init’:
net/ipv4/netfilter/nf_nat_ftp.c:123:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘nf_nat_ftp’ will never 
be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_irc.c: In function ‘nf_nat_irc_init’:
net/ipv4/netfilter/nf_nat_irc.c:85:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘help’ will never be 
NULL [-Waddress]
In file included from drivers/usb/host/ohci-hcd.c:101:0:
drivers/usb/host/ohci-dbg.c: In function ‘fill_registers_buffer’:
drivers/usb/host/ohci-dbg.c:642:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘next’ will never be 
NULL [-Waddress]
drivers/usb/host/ohci-dbg.c:661:3: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘next’ will never be 
NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c: In function ‘nf_nat_sip_init’:
net/ipv4/netfilter/nf_nat_sip.c:550:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sip’ will never 
be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:551:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sip_seq_adjust’ 
will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:552:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sip_expect’ will 
never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:553:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sdp_addr’ will 
never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:554:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sdp_port’ will 
never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:555:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sdp_session’ 
will never be NULL [-Waddress]
net/ipv4/netfilter/nf_nat_sip.c:556:2: warning: the comparison will 
always evaluate as ‘true’ for the address of ‘ip_nat_sdp_media’ will 
never be NULL [-Waddress]
Setup is 15260 bytes (padded to 15360 bytes).
System is 4654 kB
CRC 43bdb86

Not pretty :-/

Thanks,

	Ingo

Re: [GIT PULL] core/locking changes for v3.1

[Linus Torvalds]

On Mon, Jul 25, 2011 at 12:04 PM, Ingo Molnar <mingo@elte.hu> wrote:
> ..
> net/netfilter/nf_conntrack_core.c: In function ‘nf_conntrack_init’:
> net/netfilter/nf_conntrack_core.c:1579:3: warning: the comparison
> will always evaluate as ‘true’ for the address of
> ‘nf_conntrack_attach’ will never be NULL [-Waddress]

These all seem to be essentially compiler bugs.

We have macros that do generic things (in this case
"rcu_assign_pointer()" and tests their values. The fact that the tests
sometimes end up being statically true (or false) is not something the
compiler should complain about - it should use it to optimize the
code.

Sad.

We can make a compiler bug-report, or disable -Waddress. Or maybe we
can write the tests in a way that doesn't trigger the compiler bug.

This same issue is why I hated -Wsign-compare. Some of the things gcc
complained about were just technically moronic. So compiler warnings
are not always a good thing.

                  Linus

Re: [GIT PULL] core/locking changes for v3.1

[Ingo Molnar]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Jul 25, 2011 at 12:04 PM, Ingo Molnar <mingo@elte.hu> wrote:
> > ..
> > net/netfilter/nf_conntrack_core.c: In function ‘nf_conntrack_init’:
> > net/netfilter/nf_conntrack_core.c:1579:3: warning: the comparison
> > will always evaluate as ‘true’ for the address of
> > ‘nf_conntrack_attach’ will never be NULL [-Waddress]
> 
> These all seem to be essentially compiler bugs.
> 
> We have macros that do generic things (in this case
> "rcu_assign_pointer()" and tests their values. The fact that the tests
> sometimes end up being statically true (or false) is not something the
> compiler should complain about - it should use it to optimize the
> code.
> 
> Sad.
> 
> We can make a compiler bug-report, or disable -Waddress. Or maybe we
> can write the tests in a way that doesn't trigger the compiler bug.
> 
> This same issue is why I hated -Wsign-compare. Some of the things 
> gcc complained about were just technically moronic. So compiler 
> warnings are not always a good thing.

With -Wno-address added (see the first patch below) it looks a lot 
more useful:

aldebaran:~/linux/linux> make -j32 >e
sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_init’:
sound/pci/hda/patch_sigmatel.c:4385:3: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_resume’:
sound/pci/hda/patch_sigmatel.c:4925:3: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc_init’:
sound/pci/hda/patch_realtek.c:4176:2: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc_resume’:
sound/pci/hda/patch_realtek.c:4558:2: warning: statement with no 
effect [-Wunused-value]
sound/pci/hda/hda_codec.c: In function 
‘snd_hda_mixer_amp_switch_put’:
sound/pci/hda/hda_codec.c:2320:2: warning: statement with no effect 
[-Wunused-value]
sound/pci/hda/patch_realtek.c: In function ‘alc269_resume’:
sound/pci/hda/patch_realtek.c:14878:2: warning: statement with no 
effect [-Wunused-value]
drivers/md/dm.c: In function ‘split_bvec’:
drivers/md/dm.c:1052:3: warning: statement with no effect 
[-Wunused-value]
drivers/md/dm.c: In function ‘clone_bio’:
drivers/md/dm.c:1079:3: warning: statement with no effect 
[-Wunused-value]
drivers/md/dm-table.c: In function ‘dm_table_set_integrity’:
drivers/md/dm-table.c:1193:2: warning: statement with no effect 
[-Wunused-value]
Setup is 15260 bytes (padded to 15360 bytes).
System is 4654 kB
CRC 6d1b94ea

those unused-x warnings seem legit and should be fixed. For example 
the second patch below fixed the dm.c warnings.

That's with:

  gcc version 4.6.0 20110509 (Red Hat 4.6.0-7) (GCC)

so a reasonably recent GCC. I think we should kill -Waddress.

Thanks,

	Ingo

diff --git a/Makefile b/Makefile
index d018956..e651294 100644
--- a/Makefile
+++ b/Makefile
@@ -559,9 +559,9 @@ endif # $(dot-config)
 all: vmlinux
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-KBUILD_CFLAGS	+= -Os
+KBUILD_CFLAGS	+= -Os -Wno-address
 else
-KBUILD_CFLAGS	+= -O2
+KBUILD_CFLAGS	+= -O2 -Wno-address
 endif
 
 include $(srctree)/arch/$(SRCARCH)/Makefile

diff --git a/include/linux/bio.h b/include/linux/bio.h
index ce33e68..283250a 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -527,7 +527,7 @@ extern void bio_integrity_init(void);
 #define bioset_integrity_create(a, b)	(0)
 #define bio_integrity_prep(a)		(0)
 #define bio_integrity_enabled(a)	(0)
-#define bio_integrity_clone(a, b, c, d)	(0)
+#define bio_integrity_clone(a, b, c, d)	({0;})
 #define bioset_integrity_free(a)	do { } while (0)
 #define bio_integrity_free(a, b)	do { } while (0)
 #define bio_integrity_endio(a, b)	do { } while (0)

Re: [GIT PULL] core/locking changes for v3.1

[Arnaud Lacombe]

Hi,

On Mon, Jul 25, 2011 at 4:02 PM, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
>> On Mon, Jul 25, 2011 at 12:04 PM, Ingo Molnar <mingo@elte.hu> wrote:
>> > ..
>> > net/netfilter/nf_conntrack_core.c: In function ‘nf_conntrack_init’:
>> > net/netfilter/nf_conntrack_core.c:1579:3: warning: the comparison
>> > will always evaluate as ‘true’ for the address of
>> > ‘nf_conntrack_attach’ will never be NULL [-Waddress]
>>
>> These all seem to be essentially compiler bugs.
>>
>> We have macros that do generic things (in this case
>> "rcu_assign_pointer()" and tests their values. The fact that the tests
>> sometimes end up being statically true (or false) is not something the
>> compiler should complain about - it should use it to optimize the
>> code.
>>
>> Sad.
>>
>> We can make a compiler bug-report, or disable -Waddress. Or maybe we
>> can write the tests in a way that doesn't trigger the compiler bug.
>>
>> This same issue is why I hated -Wsign-compare. Some of the things
>> gcc complained about were just technically moronic. So compiler
>> warnings are not always a good thing.
>
> With -Wno-address added (see the first patch below) it looks a lot
> more useful:
>
> aldebaran:~/linux/linux> make -j32 >e
> sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_init’:
> sound/pci/hda/patch_sigmatel.c:4385:3: warning: statement with no
> effect [-Wunused-value]
> sound/pci/hda/patch_sigmatel.c: In function ‘stac92xx_resume’:
> sound/pci/hda/patch_sigmatel.c:4925:3: warning: statement with no
> effect [-Wunused-value]
> sound/pci/hda/patch_realtek.c: In function ‘alc_init’:
> sound/pci/hda/patch_realtek.c:4176:2: warning: statement with no
> effect [-Wunused-value]
> sound/pci/hda/patch_realtek.c: In function ‘alc_resume’:
> sound/pci/hda/patch_realtek.c:4558:2: warning: statement with no
> effect [-Wunused-value]
> sound/pci/hda/hda_codec.c: In function
> ‘snd_hda_mixer_amp_switch_put’:
> sound/pci/hda/hda_codec.c:2320:2: warning: statement with no effect
> [-Wunused-value]
> sound/pci/hda/patch_realtek.c: In function ‘alc269_resume’:
> sound/pci/hda/patch_realtek.c:14878:2: warning: statement with no
> effect [-Wunused-value]
> drivers/md/dm.c: In function ‘split_bvec’:
> drivers/md/dm.c:1052:3: warning: statement with no effect
> [-Wunused-value]
> drivers/md/dm.c: In function ‘clone_bio’:
> drivers/md/dm.c:1079:3: warning: statement with no effect
> [-Wunused-value]
> drivers/md/dm-table.c: In function ‘dm_table_set_integrity’:
> drivers/md/dm-table.c:1193:2: warning: statement with no effect
> [-Wunused-value]
> Setup is 15260 bytes (padded to 15360 bytes).
> System is 4654 kB
> CRC 6d1b94ea
>
> those unused-x warnings seem legit and should be fixed. For example
> the second patch below fixed the dm.c warnings.
>
> That's with:
>
>  gcc version 4.6.0 20110509 (Red Hat 4.6.0-7) (GCC)
>
> so a reasonably recent GCC. I think we should kill -Waddress.
>
> Thanks,
>
>        Ingo
>
> diff --git a/Makefile b/Makefile
> index d018956..e651294 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -559,9 +559,9 @@ endif # $(dot-config)
>  all: vmlinux
>
>  ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
> -KBUILD_CFLAGS  += -Os
> +KBUILD_CFLAGS  += -Os -Wno-address
>  else
> -KBUILD_CFLAGS  += -O2
> +KBUILD_CFLAGS  += -O2 -Wno-address
>  endif
>
did you submit this to linux-kbuild@ ?

>  include $(srctree)/arch/$(SRCARCH)/Makefile
>
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index ce33e68..283250a 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -527,7 +527,7 @@ extern void bio_integrity_init(void);
>  #define bioset_integrity_create(a, b)  (0)
>  #define bio_integrity_prep(a)          (0)
>  #define bio_integrity_enabled(a)       (0)
> -#define bio_integrity_clone(a, b, c, d)        (0)
> +#define bio_integrity_clone(a, b, c, d)        ({0;})
>  #define bioset_integrity_free(a)       do { } while (0)
>  #define bio_integrity_free(a, b)       do { } while (0)
>  #define bio_integrity_endio(a, b)      do { } while (0)
>
likewise, but to the maintainer of `include/linux/bio.h' ?

Re: [GIT PULL] core/locking changes for v3.1

[Arnaud Lacombe]

Hi,

On Mon, Jul 25, 2011 at 3:48 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Mon, Jul 25, 2011 at 12:04 PM, Ingo Molnar <mingo@elte.hu> wrote:
>> ..
>> net/netfilter/nf_conntrack_core.c: In function ‘nf_conntrack_init’:
>> net/netfilter/nf_conntrack_core.c:1579:3: warning: the comparison
>> will always evaluate as ‘true’ for the address of
>> ‘nf_conntrack_attach’ will never be NULL [-Waddress]
>
> These all seem to be essentially compiler bugs.
>
> We have macros that do generic things (in this case
> "rcu_assign_pointer()" and tests their values. The fact that the tests
> sometimes end up being statically true (or false) is not something the
> compiler should complain about - it should use it to optimize the
> code.
>
> Sad.
>
I'm not sure that it is the compiler fault, or a limitation of the C
language which has no notion of templates and obliges people to do
convoluted hack mixing __typeof__ and macros.

I'd have been interested to use the 'auto' keyword in generic static
inlines declaration. Instead, we have to deal with __typeof__ and
macros, which have no real signification for the compiler itself, so
it cannot make the difference between a conditional in a macros, there
for genericity, and "real" code, where such a warning would be useful.

my 0.2 c.
 - Arnaud

> We can make a compiler bug-report, or disable -Waddress. Or maybe we
> can write the tests in a way that doesn't trigger the compiler bug.
>
> This same issue is why I hated -Wsign-compare. Some of the things gcc
> complained about were just technically moronic. So compiler warnings
> are not always a good thing.
>
>                  Linus
>

[tip:core/urgent] lockdep: Fix up warning

[tip-bot for Peter Zijlstra]

Commit-ID:  70a0686a72c7a7e554b404ca11406ceec709d425
Gitweb:     http://git.kernel.org/tip/70a0686a72c7a7e554b404ca11406ceec709d425
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Mon, 25 Jul 2011 12:09:59 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 4 Aug 2011 10:17:41 +0200

lockdep: Fix up warning

On Sun, 2011-07-24 at 21:06 -0400, Arnaud Lacombe wrote:

> /src/linux/linux/kernel/lockdep.c: In function 'mark_held_locks':
> /src/linux/linux/kernel/lockdep.c:2471:31: warning: comparison of
> distinct pointer types lacks a cast

The warning is harmless in this case, but the below makes it go away.

Reported-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311588599.2617.56.camel@laptop
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/lockdep.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 74ca247..5903586 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2468,7 +2468,7 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
 
 		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
 
-		if (hlock_class(hlock)->key == &__lockdep_no_validate__)
+		if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
 			continue;
 
 		if (!mark_lock(curr, hlock, usage_bit))