If you don't know what to do here, say N.
+CONFIG_PREEMPT
+ This option reduces the latency of the kernel when reacting to
+ real-time or interactive events by allowing a low priority process to
+ be preempted even if it is in kernel mode executing a system call.
+ This allows applications to run more reliably even when the system is
+ under load.
+
+ Say Y here if you are building a kernel for a desktop, embedded
+ or real-time system. Say N if you are unsure.
+
CONFIG_X86
This is Linux's home port. Linux was originally native to the Intel
386, and runs on all the later x86 processors including the Intel
bool 'Math emulation' CONFIG_MATH_EMULATION
bool 'MTRR (Memory Type Range Register) support' CONFIG_MTRR
bool 'Symmetric multi-processing support' CONFIG_SMP
+bool 'Preemptible Kernel' CONFIG_PREEMPT
if [ "$CONFIG_SMP" != "y" ]; then
bool 'Local APIC support on uniprocessors' CONFIG_X86_UP_APIC
dep_bool 'IO-APIC support on uniprocessors' CONFIG_X86_UP_IOAPIC $CONFIG_X86_UP_APIC
bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
fi
-if [ "$CONFIG_SMP" = "y" -a "$CONFIG_X86_CMPXCHG" = "y" ]; then
- define_bool CONFIG_HAVE_DEC_LOCK y
+if [ "$CONFIG_SMP" = "y" -o "$CONFIG_PREEMPT" = "y" ]; then
+ if [ "$CONFIG_X86_CMPXCHG" = "y" ]; then
+ define_bool CONFIG_HAVE_DEC_LOCK y
+ fi
fi
+
endmenu
mainmenu_option next_comment
NT_MASK = 0x00004000
VM_MASK = 0x00020000
+/* These are offsets into the irq_stat structure
+ * There is one per cpu and it is aligned to 32
+ * byte boundry (we put that here as a shift count)
+ */
+irq_array_shift = CONFIG_X86_L1_CACHE_SHIFT
+irq_stat_local_irq_count = 4
+irq_stat_local_bh_count = 8
+
+#ifdef CONFIG_SMP
+#define GET_CPU_INDX movl TI_CPU(%ebx),%eax; \
+ shll $irq_array_shift,%eax
+#define GET_CURRENT_CPU_INDX GET_THREAD_INFO(%ebx); \
+ GET_CPU_INDX
+#define CPU_INDX (,%eax)
+#else
+#define GET_CPU_INDX
+#define GET_CURRENT_CPU_INDX GET_THREAD_INFO(%ebx)
+#define CPU_INDX
+#endif
+
+#ifdef CONFIG_PREEMPT
+#define preempt_stop cli
+#define init_ret_intr \
+ cli; \
+ decl TI_PRE_COUNT(%ebx);
+#else
+#define preempt_stop
+#define init_ret_intr
+#define resume_kernel restore_all
+#endif
+
#define SAVE_ALL \
cld; \
pushl %es; \
ALIGN
ENTRY(ret_from_intr)
GET_THREAD_INFO(%ebx)
+ init_ret_intr
ret_from_exception:
movl EFLAGS(%esp),%eax # mix EFLAGS and CS
movb CS(%esp),%al
testl $(VM_MASK | 3),%eax
- jz restore_all # returning to kernel-space or vm86-space
+ jz resume_kernel # returning to kernel or vm86-space
ENTRY(resume_userspace)
cli # make sure we don't miss an interrupt setting need_resched
# or sigpending between sampling and the iret
jne work_pending
jmp restore_all
+#ifdef CONFIG_PREEMPT
+ENTRY(resume_kernel)
+ cmpl $0,TI_PRE_COUNT(%ebx)
+ jnz restore_all
+ movl TI_FLAGS(%ebx),%ecx
+ testb $_TIF_NEED_RESCHED,%cl
+ jz restore_all
+ movl SYMBOL_NAME(irq_stat)+irq_stat_local_bh_count CPU_INDX,%ecx
+ addl SYMBOL_NAME(irq_stat)+irq_stat_local_irq_count CPU_INDX,%ecx
+ jnz restore_all
+ incl TI_PRE_COUNT(%ebx)
+ sti
+ call SYMBOL_NAME(preempt_schedule)
+ jmp ret_from_intr
+#endif
+
# system call handler stub
ALIGN
ENTRY(system_call)
GET_THREAD_INFO(%ebx)
call *%edi
addl $8,%esp
+ preempt_stop
jmp ret_from_exception
ENTRY(coprocessor_error)
movl %cr0,%eax
testl $0x4,%eax # EM (math emulation bit)
jne device_not_available_emulate
+ preempt_stop
call SYMBOL_NAME(math_state_restore)
jmp ret_from_exception
device_not_available_emulate:
pushl $0 # temporary storage for ORIG_EIP
call SYMBOL_NAME(math_emulate)
addl $4,%esp
+ preempt_stop
jmp ret_from_exception
ENTRY(debug)
#include <linux/config.h>
#include <linux/sched.h>
+#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/math_emu.h>
void kernel_fpu_begin(void)
{
+ preempt_disable();
if (test_thread_flag(TIF_USEDFPU)) {
__save_init_fpu(current);
return;
/*
* The target CPU will unlock the migration spinlock:
*/
- spin_lock(&migration_lock);
+ _raw_spin_lock(&migration_lock);
new_task = p;
send_IPI_mask(1 << cpu, TASK_MIGRATION_VECTOR);
}
ack_APIC_irq();
p = new_task;
- spin_unlock(&migration_lock);
+ _raw_spin_unlock(&migration_lock);
sched_task_migrated(p);
}
/*
*
* Careful.. There are problems with IBM-designed IRQ13 behaviour.
* Don't touch unless you *really* know how it works.
+ *
+ * Must be called with kernel preemption disabled.
*/
asmlinkage void math_state_restore(struct pt_regs regs)
{
active_mm = current->active_mm;
current->mm = mm;
current->active_mm = mm;
- task_unlock(current);
activate_mm(active_mm, mm);
+ task_unlock(current);
mm_release();
if (old_mm) {
if (active_mm != old_mm) BUG();
#define synchronize_irq() barrier()
+#define release_irqlock(cpu) do { } while (0)
+
#else
#include <asm/atomic.h>
enum fixed_addresses idx;
unsigned long vaddr;
+ preempt_disable();
if (page < highmem_start_page)
return page_address(page);
unsigned long vaddr = (unsigned long) kvaddr;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
- if (vaddr < FIXADDR_START) // FIXME
+ if (vaddr < FIXADDR_START) { // FIXME
+ preempt_enable();
return;
+ }
if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
BUG();
pte_clear(kmap_pte-idx);
__flush_tlb_one(vaddr);
#endif
+
+ preempt_enable();
}
#endif /* __KERNEL__ */
#define __STR(x) #x
#define STR(x) __STR(x)
+#define GET_THREAD_INFO \
+ "movl $-8192, %ebx\n\t" \
+ "andl %esp, %ebx\n\t"
+
+#ifdef CONFIG_PREEMPT
+#define BUMP_LOCK_COUNT \
+ GET_THREAD_INFO \
+ "incl 16(%ebx)\n\t"
+#else
+#define BUMP_LOCK_COUNT
+#endif
+
#define SAVE_ALL \
"cld\n\t" \
"pushl %es\n\t" \
"pushl %ebx\n\t" \
"movl $" STR(__KERNEL_DS) ",%edx\n\t" \
"movl %edx,%ds\n\t" \
- "movl %edx,%es\n\t"
+ "movl %edx,%es\n\t" \
+ BUMP_LOCK_COUNT
#define IRQ_NAME2(nr) nr##_interrupt(void)
#define IRQ_NAME(nr) IRQ_NAME2(IRQ##nr)
#define __ASM_I386_I387_H
#include <linux/sched.h>
+#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>
#include <asm/user.h>
extern void restore_fpu( struct task_struct *tsk );
extern void kernel_fpu_begin(void);
-#define kernel_fpu_end() stts()
+#define kernel_fpu_end() do { stts(); preempt_enable(); } while(0)
#define unlazy_fpu( tsk ) do { \
{
unsigned long *ret;
+ preempt_disable();
if ((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)(*ret);
ret[0] = 0;
pgtable_cache_size--;
- } else
+ preempt_enable();
+ } else {
+ preempt_enable();
ret = (unsigned long *)get_pgd_slow();
+ }
return (pgd_t *)ret;
}
static inline void free_pgd_fast(pgd_t *pgd)
{
+ preempt_disable();
*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
+ preempt_enable();
}
static inline void free_pgd_slow(pgd_t *pgd)
{
unsigned long *ret;
+ preempt_disable();
if ((ret = (unsigned long *)pte_quicklist) != NULL) {
pte_quicklist = (unsigned long *)(*ret);
ret[0] = ret[1];
pgtable_cache_size--;
}
+ preempt_enable();
return (pte_t *)ret;
}
static inline void pte_free_fast(pte_t *pte)
{
+ preempt_disable();
*(unsigned long *)pte = (unsigned long) pte_quicklist;
pte_quicklist = (unsigned long *) pte;
pgtable_cache_size++;
+ preempt_enable();
}
static __inline__ void pte_free_slow(pte_t *pte)
extern spinlock_t kernel_flag;
+#ifdef CONFIG_SMP
#define kernel_locked() spin_is_locked(&kernel_flag)
+#else
+#ifdef CONFIG_PREEMPT
+#define kernel_locked() preempt_get_count()
+#else
+#define kernel_locked() 1
+#endif
+#endif
/*
* Release global kernel lock and global interrupt lock
*/
static __inline__ void lock_kernel(void)
{
+#ifdef CONFIG_PREEMPT
+ if (current->lock_depth == -1)
+ spin_lock(&kernel_flag);
+ ++current->lock_depth;
+#else
#if 1
if (!++current->lock_depth)
spin_lock(&kernel_flag);
:"=m" (__dummy_lock(&kernel_flag)),
"=m" (current->lock_depth));
#endif
+#endif
}
static __inline__ void unlock_kernel(void)
#include <asm/hardirq.h>
#define __cpu_bh_enable(cpu) \
- do { barrier(); local_bh_count(cpu)--; } while (0)
+ do { barrier(); local_bh_count(cpu)--; preempt_enable(); } while (0)
#define cpu_bh_disable(cpu) \
- do { local_bh_count(cpu)++; barrier(); } while (0)
+ do { preempt_disable(); local_bh_count(cpu)++; barrier(); } while (0)
#define local_bh_disable() cpu_bh_disable(smp_processor_id())
#define __local_bh_enable() __cpu_bh_enable(smp_processor_id())
* If you change the offsets in irq_stat then you have to
* update this code as well.
*/
-#define local_bh_enable() \
+#define _local_bh_enable() \
do { \
unsigned int *ptr = &local_bh_count(smp_processor_id()); \
\
/* no registers clobbered */ ); \
} while (0)
+#define local_bh_enable() do { _local_bh_enable(); preempt_enable(); } while (0)
+
#endif /* __ASM_SOFTIRQ_H */
:"=m" (lock->lock) : : "memory"
-static inline void spin_unlock(spinlock_t *lock)
+static inline void _raw_spin_unlock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
if (lock->magic != SPINLOCK_MAGIC)
:"=q" (oldval), "=m" (lock->lock) \
:"0" (oldval) : "memory"
-static inline void spin_unlock(spinlock_t *lock)
+static inline void _raw_spin_unlock(spinlock_t *lock)
{
char oldval = 1;
#if SPINLOCK_DEBUG
#endif
-static inline int spin_trylock(spinlock_t *lock)
+static inline int _raw_spin_trylock(spinlock_t *lock)
{
char oldval;
__asm__ __volatile__(
return oldval > 0;
}
-static inline void spin_lock(spinlock_t *lock)
+static inline void _raw_spin_lock(spinlock_t *lock)
{
#if SPINLOCK_DEBUG
__label__ here;
*/
/* the spinlock helpers are in arch/i386/kernel/semaphore.c */
-static inline void read_lock(rwlock_t *rw)
+static inline void _raw_read_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
__build_read_lock(rw, "__read_lock_failed");
}
-static inline void write_lock(rwlock_t *rw)
+static inline void _raw_write_lock(rwlock_t *rw)
{
#if SPINLOCK_DEBUG
if (rw->magic != RWLOCK_MAGIC)
__build_write_lock(rw, "__write_lock_failed");
}
-#define read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
-#define write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
+#define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
+#define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
-static inline int write_trylock(rwlock_t *lock)
+static inline int _raw_write_trylock(rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;
if (atomic_sub_and_test(RW_LOCK_BIAS, count))
struct exec_domain *exec_domain; /* execution domain */
__u32 flags; /* low level flags */
__u32 cpu; /* current CPU */
+ __s32 preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
#define TI_EXEC_DOMAIN 0x00000004
#define TI_FLAGS 0x00000008
#define TI_CPU 0x0000000C
-#define TI_ADDR_LIMIT 0x00000010
+#define TI_PRE_COUNT 0x00000010
+#define TI_ADDR_LIMIT 0x00000014
#endif
}
#else
-# define br_read_lock(idx) ((void)(idx))
-# define br_read_unlock(idx) ((void)(idx))
-# define br_write_lock(idx) ((void)(idx))
-# define br_write_unlock(idx) ((void)(idx))
-#endif
+# define br_read_lock(idx) ({ (void)(idx); preempt_disable(); })
+# define br_read_unlock(idx) ({ (void)(idx); preempt_enable(); })
+# define br_write_lock(idx) ({ (void)(idx); preempt_disable(); })
+# define br_write_unlock(idx) ({ (void)(idx); preempt_enable(); })
+#endif /* CONFIG_SMP */
/*
* Now enumerate all of the possible sw/hw IRQ protected
#define TASK_UNINTERRUPTIBLE 2
#define TASK_ZOMBIE 4
#define TASK_STOPPED 8
+#define PREEMPT_ACTIVE 0x4000000
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
#define smp_processor_id() 0
#define hard_smp_processor_id() 0
#define smp_threads_ready 1
+#ifndef CONFIG_PREEMPT
#define kernel_lock()
+#endif
#define cpu_logical_map(cpu) 0
#define cpu_number_map(cpu) 0
#define smp_call_function(func,info,retry,wait) ({ 0; })
#include <linux/config.h>
-#ifndef CONFIG_SMP
+#if !defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT)
#define lock_kernel() do { } while(0)
#define unlock_kernel() do { } while(0)
#define __LINUX_SPINLOCK_H
#include <linux/config.h>
+#include <linux/linkage.h>
+#include <linux/compiler.h>
+#include <linux/thread_info.h>
+#include <linux/kernel.h>
/*
* These are the generic versions of the spinlocks and read-write
#if (DEBUG_SPINLOCKS < 1)
+#ifndef CONFIG_PREEMPT
#define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
#define ATOMIC_DEC_AND_LOCK
+#endif
/*
* Your basic spinlocks, allowing only a single CPU anywhere
#endif
#define spin_lock_init(lock) do { } while(0)
-#define spin_lock(lock) (void)(lock) /* Not "unused variable". */
+#define _raw_spin_lock(lock) (void)(lock) /* Not "unused variable". */
#define spin_is_locked(lock) (0)
-#define spin_trylock(lock) ({1; })
+#define _raw_spin_trylock(lock) ({1; })
#define spin_unlock_wait(lock) do { } while(0)
-#define spin_unlock(lock) do { } while(0)
+#define _raw_spin_unlock(lock) do { } while(0)
#elif (DEBUG_SPINLOCKS < 2)
#endif
#define rwlock_init(lock) do { } while(0)
-#define read_lock(lock) (void)(lock) /* Not "unused variable". */
-#define read_unlock(lock) do { } while(0)
-#define write_lock(lock) (void)(lock) /* Not "unused variable". */
-#define write_unlock(lock) do { } while(0)
+#define _raw_read_lock(lock) (void)(lock) /* Not "unused variable". */
+#define _raw_read_unlock(lock) do { } while(0)
+#define _raw_write_lock(lock) (void)(lock) /* Not "unused variable". */
+#define _raw_write_unlock(lock) do { } while(0)
#endif /* !SMP */
+#ifdef CONFIG_PREEMPT
+
+asmlinkage void preempt_schedule(void);
+
+#define preempt_get_count() (current_thread_info()->preempt_count)
+
+#define preempt_disable() \
+do { \
+ ++current_thread_info()->preempt_count; \
+ barrier(); \
+} while (0)
+
+#define preempt_enable_no_resched() \
+do { \
+ --current_thread_info()->preempt_count; \
+ barrier(); \
+} while (0)
+
+#define preempt_enable() \
+do { \
+ --current_thread_info()->preempt_count; \
+ barrier(); \
+ if (unlikely(!(current_thread_info()->preempt_count) && \
+ test_thread_flag(TIF_NEED_RESCHED))) \
+ preempt_schedule(); \
+} while (0)
+
+#define spin_lock(lock) \
+do { \
+ preempt_disable(); \
+ _raw_spin_lock(lock); \
+} while(0)
+
+#define spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
+ 1 : ({preempt_enable(); 0;});})
+#define spin_unlock(lock) \
+do { \
+ _raw_spin_unlock(lock); \
+ preempt_enable(); \
+} while (0)
+
+#define read_lock(lock) ({preempt_disable(); _raw_read_lock(lock);})
+#define read_unlock(lock) ({_raw_read_unlock(lock); preempt_enable();})
+#define write_lock(lock) ({preempt_disable(); _raw_write_lock(lock);})
+#define write_unlock(lock) ({_raw_write_unlock(lock); preempt_enable();})
+#define write_trylock(lock) ({preempt_disable();_raw_write_trylock(lock) ? \
+ 1 : ({preempt_enable(); 0;});})
+
+#else
+
+#define preempt_get_count() do { } while (0)
+#define preempt_disable() do { } while (0)
+#define preempt_enable_no_resched() do {} while(0)
+#define preempt_enable() do { } while (0)
+
+#define spin_lock(lock) _raw_spin_lock(lock)
+#define spin_trylock(lock) _raw_spin_trylock(lock)
+#define spin_unlock(lock) _raw_spin_unlock(lock)
+
+#define read_lock(lock) _raw_read_lock(lock)
+#define read_unlock(lock) _raw_read_unlock(lock)
+#define write_lock(lock) _raw_write_lock(lock)
+#define write_unlock(lock) _raw_write_unlock(lock)
+#define write_trylock(lock) _raw_write_trylock(lock)
+#endif
+
/* "lock on reference count zero" */
#ifndef ATOMIC_DEC_AND_LOCK
#include <asm/atomic.h>
/* more a memory barrier than a real lock */
task_lock(tsk);
tsk->mm = NULL;
- task_unlock(tsk);
enter_lazy_tlb(mm, current, smp_processor_id());
+ task_unlock(tsk);
mmput(mm);
}
}
if (p->binfmt && p->binfmt->module)
__MOD_INC_USE_COUNT(p->binfmt->module);
+#ifdef CONFIG_PREEMPT
+ /*
+ * schedule_tail drops this_rq()->lock so we compensate with a count
+ * of 1. Also, we want to start with kernel preemption disabled.
+ */
+ p->thread_info->preempt_count = 1;
+#endif
p->did_exec = 0;
p->swappable = 0;
p->state = TASK_UNINTERRUPTIBLE;
EXPORT_SYMBOL(interruptible_sleep_on);
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
EXPORT_SYMBOL(schedule);
+#ifdef CONFIG_PREEMPT
+EXPORT_SYMBOL(preempt_schedule);
+#endif
EXPORT_SYMBOL(schedule_timeout);
EXPORT_SYMBOL(sys_sched_yield);
EXPORT_SYMBOL(set_user_nice);
struct runqueue *__rq;
repeat_lock_task:
+ preempt_disable();
__rq = task_rq(p);
spin_lock_irqsave(&__rq->lock, *flags);
if (unlikely(__rq != task_rq(p))) {
spin_unlock_irqrestore(&__rq->lock, *flags);
+ preempt_enable();
goto repeat_lock_task;
}
return __rq;
static inline void unlock_task_rq(runqueue_t *rq, unsigned long *flags)
{
spin_unlock_irqrestore(&rq->lock, *flags);
+ preempt_enable();
}
/*
* Adding/removing a task to/from a priority array:
#ifdef CONFIG_SMP
int need_resched, nrpolling;
+ preempt_disable();
/* minimise the chance of sending an interrupt to poll_idle() */
nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
if (!need_resched && !nrpolling && (p->thread_info->cpu != smp_processor_id()))
smp_send_reschedule(p->thread_info->cpu);
+ preempt_enable();
#else
set_tsk_need_resched(p);
#endif
runqueue_t *rq;
repeat:
+ preempt_disable();
rq = task_rq(p);
while (unlikely(rq->curr == p)) {
cpu_relax();
rq = lock_task_rq(p, &flags);
if (unlikely(rq->curr == p)) {
unlock_task_rq(rq, &flags);
+ preempt_enable();
goto repeat;
}
unlock_task_rq(rq, &flags);
+ preempt_enable();
}
/*
void wake_up_forked_process(task_t * p)
{
- runqueue_t *rq = this_rq();
+ runqueue_t *rq;
+
+ preempt_disable();
+ rq = this_rq();
p->state = TASK_RUNNING;
if (!rt_task(p)) {
p->thread_info->cpu = smp_processor_id();
activate_task(p, rq);
spin_unlock_irq(&rq->lock);
+ preempt_enable();
}
asmlinkage void schedule_tail(task_t *prev)
*/
asmlinkage void schedule(void)
{
- task_t *prev = current, *next;
- runqueue_t *rq = this_rq();
+ task_t *prev, *next;
+ runqueue_t *rq;
prio_array_t *array;
list_t *queue;
int idx;
if (unlikely(in_interrupt()))
BUG();
+
+ preempt_disable();
+ prev = current;
+ rq = this_rq();
+
release_kernel_lock(prev, smp_processor_id());
spin_lock_irq(&rq->lock);
+#ifdef CONFIG_PREEMPT
+ /*
+ * if entering from preempt_schedule, off a kernel preemption,
+ * go straight to picking the next task.
+ */
+ if (unlikely(preempt_get_count() & PREEMPT_ACTIVE))
+ goto pick_next_task;
+#endif
+
switch (prev->state) {
case TASK_RUNNING:
prev->sleep_timestamp = jiffies;
default:
deactivate_task(prev, rq);
}
-#if CONFIG_SMP
+#if CONFIG_SMP || CONFIG_PREEMPT
pick_next_task:
#endif
if (unlikely(!rq->nr_running)) {
spin_unlock_irq(&rq->lock);
reacquire_kernel_lock(current);
+ preempt_enable_no_resched();
return;
}
+#ifdef CONFIG_PREEMPT
+/*
+ * this is is the entry point to schedule() from in-kernel preemption.
+ */
+asmlinkage void preempt_schedule(void)
+{
+ do {
+ current_thread_info()->preempt_count += PREEMPT_ACTIVE;
+ schedule();
+ current_thread_info()->preempt_count -= PREEMPT_ACTIVE;
+ barrier();
+ } while (test_thread_flag(TIF_NEED_RESCHED));
+}
+#endif /* CONFIG_PREEMPT */
+
/*
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
asmlinkage long sys_sched_yield(void)
{
- runqueue_t *rq = this_rq();
+ runqueue_t *rq;
prio_array_t *array;
+ preempt_disable();
+ rq = this_rq();
+
/*
* Decrease the yielding task's priority by one, to avoid
* livelocks. This priority loss is temporary, it's recovered
__set_bit(current->prio, array->bitmap);
}
spin_unlock(&rq->lock);
+ preempt_enable_no_resched();
schedule();
static struct net_proto_family *net_families[NPROTO];
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
static atomic_t net_family_lockct = ATOMIC_INIT(0);
static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED;
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