xfs: remove nr_to_write writeback windup.

[safe/jmp/linux-2.6] / kernel / trace / trace_stack.c

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index e644af9..f4bc9b2 100644 (file)
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -27,8 +27,8 @@ static struct stack_trace max_stack_trace = {
 };
 
 static unsigned long max_stack_size;
-static raw_spinlock_t max_stack_lock =
-       (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+static arch_spinlock_t max_stack_lock =
+       (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
 static int stack_trace_disabled __read_mostly;
 static DEFINE_PER_CPU(int, trace_active);
@@ -54,7 +54,7 @@ static inline void check_stack(void)
                return;
 
        local_irq_save(flags);
-       __raw_spin_lock(&max_stack_lock);
+       arch_spin_lock(&max_stack_lock);
 
        /* a race could have already updated it */
        if (this_size <= max_stack_size)
@@ -103,7 +103,7 @@ static inline void check_stack(void)
        }
 
  out:
-       __raw_spin_unlock(&max_stack_lock);
+       arch_spin_unlock(&max_stack_lock);
        local_irq_restore(flags);
 }
 
@@ -157,6 +157,7 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
        unsigned long val, flags;
        char buf[64];
        int ret;
+       int cpu;
 
        if (count >= sizeof(buf))
                return -EINVAL;
@@ -171,9 +172,20 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
                return ret;
 
        local_irq_save(flags);
-       __raw_spin_lock(&max_stack_lock);
+
+       /*
+        * In case we trace inside arch_spin_lock() or after (NMI),
+        * we will cause circular lock, so we also need to increase
+        * the percpu trace_active here.
+        */
+       cpu = smp_processor_id();
+       per_cpu(trace_active, cpu)++;
+
+       arch_spin_lock(&max_stack_lock);
        *ptr = val;
-       __raw_spin_unlock(&max_stack_lock);
+       arch_spin_unlock(&max_stack_lock);
+
+       per_cpu(trace_active, cpu)--;
        local_irq_restore(flags);
 
        return count;
@@ -186,63 +198,58 @@ static const struct file_operations stack_max_size_fops = {
 };
 
 static void *
-t_next(struct seq_file *m, void *v, loff_t *pos)
+__next(struct seq_file *m, loff_t *pos)
 {
-       long i;
+       long n = *pos - 1;
 
-       (*pos)++;
-
-       if (v == SEQ_START_TOKEN)
-               i = 0;
-       else {
-               i = *(long *)v;
-               i++;
-       }
-
-       if (i >= max_stack_trace.nr_entries ||
-           stack_dump_trace[i] == ULONG_MAX)
+       if (n >= max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX)
                return NULL;
 
-       m->private = (void *)i;
-
+       m->private = (void *)n;
        return &m->private;
 }
 
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+       (*pos)++;
+       return __next(m, pos);
+}
+
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
-       void *t = SEQ_START_TOKEN;
-       loff_t l = 0;
+       int cpu;
 
        local_irq_disable();
-       __raw_spin_lock(&max_stack_lock);
+
+       cpu = smp_processor_id();
+       per_cpu(trace_active, cpu)++;
+
+       arch_spin_lock(&max_stack_lock);
 
        if (*pos == 0)
                return SEQ_START_TOKEN;
 
-       for (; t && l < *pos; t = t_next(m, t, &l))
-               ;
-
-       return t;
+       return __next(m, pos);
 }
 
 static void t_stop(struct seq_file *m, void *p)
 {
-       __raw_spin_unlock(&max_stack_lock);
+       int cpu;
+
+       arch_spin_unlock(&max_stack_lock);
+
+       cpu = smp_processor_id();
+       per_cpu(trace_active, cpu)--;
+
        local_irq_enable();
 }
 
 static int trace_lookup_stack(struct seq_file *m, long i)
 {
        unsigned long addr = stack_dump_trace[i];
-#ifdef CONFIG_KALLSYMS
-       char str[KSYM_SYMBOL_LEN];
-
-       sprint_symbol(str, addr);
 
-       return seq_printf(m, "%s\n", str);
-#else
-       return seq_printf(m, "%p\n", (void*)addr);
-#endif
+       return seq_printf(m, "%pF\n", (void *)addr);
 }
 
 static void print_disabled(struct seq_file *m)
@@ -301,29 +308,26 @@ static const struct seq_operations stack_trace_seq_ops = {
 
 static int stack_trace_open(struct inode *inode, struct file *file)
 {
-       int ret;
-
-       ret = seq_open(file, &stack_trace_seq_ops);
-
-       return ret;
+       return seq_open(file, &stack_trace_seq_ops);
 }
 
 static const struct file_operations stack_trace_fops = {
        .open           = stack_trace_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
+       .release        = seq_release,
 };
 
 int
 stack_trace_sysctl(struct ctl_table *table, int write,
-                  struct file *file, void __user *buffer, size_t *lenp,
+                  void __user *buffer, size_t *lenp,
                   loff_t *ppos)
 {
        int ret;
 
        mutex_lock(&stack_sysctl_mutex);
 
-       ret = proc_dointvec(table, write, file, buffer, lenp, ppos);
+       ret = proc_dointvec(table, write, buffer, lenp, ppos);
 
        if (ret || !write ||
            (last_stack_tracer_enabled == !!stack_tracer_enabled))