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oprofile: disable write access to oprofilefs while profiler is running

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Oprofile counters are setup when profiling is disabled. Thus, writing
to oprofilefs has no immediate effect. Changes are updated only after
oprofile is reenabled.

To keep userland and kernel states synchronized, we now allow
configuration of oprofile only if profiling is disabled.  In this case
it checks if the profiler is running and then disables write access to
oprofilefs by returning -EBUSY. The change should be backward
compatible with current oprofile userland daemon.

Acked-by: Maynard Johnson <maynardj@us.ibm.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
This commit is contained in:
Robert Richter 2010-10-04 21:09:36 +02:00
parent 0361e02342
commit 7df01d96b2
4 changed files with 19 additions and 21 deletions
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21
drivers/oprofile/oprof.c
View file

@ -225,26 +225,17 @@ void oprofile_shutdown(void)
mutex_unlock(&start_mutex);
}
int oprofile_set_backtrace(unsigned long val)
int oprofile_set_ulong(unsigned long *addr, unsigned long val)
{
int err = 0;
int err = -EBUSY;
mutex_lock(&start_mutex);
if (oprofile_started) {
err = -EBUSY;
goto out;
if (!oprofile_started) {
*addr = val;
err = 0;
}
if (!oprofile_ops.backtrace) {
err = -EINVAL;
goto out;
}
oprofile_backtrace_depth = val;
out:
mutex_unlock(&start_mutex);
return err;
}

2
drivers/oprofile/oprof.h
View file

@ -37,7 +37,7 @@ void oprofile_create_files(struct super_block *sb, struct dentry *root);
int oprofile_timer_init(struct oprofile_operations *ops);
void oprofile_timer_exit(void);
int oprofile_set_backtrace(unsigned long depth);
int oprofile_set_ulong(unsigned long *addr, unsigned long val);
int oprofile_set_timeout(unsigned long time);
#endif /* OPROF_H */

7
drivers/oprofile/oprofile_files.c
View file

@ -79,14 +79,17 @@ static ssize_t depth_write(struct file *file, char const __user *buf, size_t cou
if (*offset)
return -EINVAL;
if (!oprofile_ops.backtrace)
return -EINVAL;
retval = oprofilefs_ulong_from_user(&val, buf, count);
if (retval)
return retval;
retval = oprofile_set_backtrace(val);
retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
if (retval)
return retval;
return count;
}

10
drivers/oprofile/oprofilefs.c
View file

@ -91,16 +91,20 @@ static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count
static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
{
unsigned long *value = file->private_data;
unsigned long value;
int retval;
if (*offset)
return -EINVAL;
retval = oprofilefs_ulong_from_user(value, buf, count);
retval = oprofilefs_ulong_from_user(&value, buf, count);
if (retval)
return retval;
retval = oprofile_set_ulong(file->private_data, value);
if (retval)
return retval;
return count;
}