/* endless idle loop with no priority at all */
while (1) {
while (!need_resched()) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ /*
+ * Mark this as an RCU critical section so that
+ * synchronize_kernel() in the unload path waits
+ * for our completion.
+ */
+ rcu_read_lock();
+ idle = pm_idle;
if (!idle)
idle = default_idle;
irq_stat[smp_processor_id()].idle_timestamp = jiffies;
idle();
+ rcu_read_unlock();
}
schedule();
}
printk("monitor/mwait feature present.\n");
/*
* Skip, if setup has overridden idle.
- * Also, take care of system with asymmetric CPUs.
- * Use, mwait_idle only if all cpus support it.
- * If not, we fallback to default_idle()
+ * One CPU supports mwait => All CPUs supports mwait
*/
if (!pm_idle) {
printk("using mwait in idle threads.\n");
pm_idle = mwait_idle;
}
- return;
}
- pm_idle = default_idle;
- return;
}
static int __init idle_setup (char *str)
void exit_thread(void)
{
struct task_struct *tsk = current;
+ struct thread_struct *t = &tsk->thread;
/* The process may have allocated an io port bitmap... nuke it. */
- if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) {
+ if (unlikely(NULL != t->io_bitmap_ptr)) {
int cpu = get_cpu();
- struct tss_struct *tss = init_tss + cpu;
- kfree(tsk->thread.io_bitmap_ptr);
- tsk->thread.io_bitmap_ptr = NULL;
+ struct tss_struct *tss = &per_cpu(init_tss, cpu);
+
+ kfree(t->io_bitmap_ptr);
+ t->io_bitmap_ptr = NULL;
+ /*
+ * Careful, clear this in the TSS too:
+ */
+ memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
+ t->io_bitmap_max = 0;
+ tss->io_bitmap_owner = NULL;
+ tss->io_bitmap_max = 0;
tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
put_cpu();
}
tsk = current;
if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) {
p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
- if (!p->thread.io_bitmap_ptr)
+ if (!p->thread.io_bitmap_ptr) {
+ p->thread.io_bitmap_max = 0;
return -ENOMEM;
+ }
memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr,
IO_BITMAP_BYTES);
}
err = 0;
out:
- if (err && p->thread.io_bitmap_ptr)
+ if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
+ p->thread.io_bitmap_max = 0;
+ }
return err;
}
return 1;
}
+static inline void
+handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss)
+{
+ if (!next->io_bitmap_ptr) {
+ /*
+ * Disable the bitmap via an invalid offset. We still cache
+ * the previous bitmap owner and the IO bitmap contents:
+ */
+ tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
+ return;
+ }
+ if (likely(next == tss->io_bitmap_owner)) {
+ /*
+ * Previous owner of the bitmap (hence the bitmap content)
+ * matches the next task, we dont have to do anything but
+ * to set a valid offset in the TSS:
+ */
+ tss->io_bitmap_base = IO_BITMAP_OFFSET;
+ return;
+ }
+ /*
+ * Lazy TSS's I/O bitmap copy. We set an invalid offset here
+ * and we let the task to get a GPF in case an I/O instruction
+ * is performed. The handler of the GPF will verify that the
+ * faulting task has a valid I/O bitmap and, it true, does the
+ * real copy and restart the instruction. This will save us
+ * redundant copies when the currently switched task does not
+ * perform any I/O during its timeslice.
+ */
+ tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+}
/*
* This special macro can be used to load a debugging register
*/
struct thread_struct *prev = &prev_p->thread,
*next = &next_p->thread;
int cpu = smp_processor_id();
- struct tss_struct *tss = init_tss + cpu;
+ struct tss_struct *tss = &per_cpu(init_tss, cpu);
/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
loaddebug(next, 7);
}
- if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
- if (next->io_bitmap_ptr) {
- /*
- * 4 cachelines copy ... not good, but not that
- * bad either. Anyone got something better?
- * This only affects processes which use ioperm().
- * [Putting the TSSs into 4k-tlb mapped regions
- * and playing VM tricks to switch the IO bitmap
- * is not really acceptable.]
- */
- memcpy(tss->io_bitmap, next->io_bitmap_ptr,
- IO_BITMAP_BYTES);
- tss->io_bitmap_base = IO_BITMAP_OFFSET;
- } else
- /*
- * a bitmap offset pointing outside of the TSS limit
- * causes a nicely controllable SIGSEGV if a process
- * tries to use a port IO instruction. The first
- * sys_ioperm() call sets up the bitmap properly.
- */
- tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
- }
+ if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr))
+ handle_io_bitmap(next, tss);
+
return prev_p;
}
child_tidptr = (int __user *)regs.edi;
if (!newsp)
newsp = regs.esp;
- return do_fork(clone_flags & ~CLONE_IDLETASK, newsp, ®s, 0, parent_tidptr, child_tidptr);
+ return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
}
/*
git://git.onelab.eu / linux-2.6.git / blobdiff