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intel_th: msu: Add a sysfs attribute to trigger window switch

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Now that we have the means to trigger a window switch for the MSU trace
store, add a sysfs file to allow triggering it from userspace.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Shishkin 2019-05-03 11:44:50 +03:00 committed by Greg Kroah-Hartman
parent 4840572d3d
commit 6cac7866c2
2 changed files with 36 additions and 0 deletions
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8
Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc
View File

@ -30,4 +30,12 @@ Description: (RW) Configure MSC buffer size for "single" or "multi" modes.
there are no active users and tracing is not enabled) and then there are no active users and tracing is not enabled) and then
allocates a new one. allocates a new one.
What: /sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/win_switch
Date: May 2019
KernelVersion: 5.2
Contact: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Description: (RW) Trigger window switch for the MSC's buffer, in
multi-window mode. In "multi" mode, accepts writes of "1", thereby
triggering a window switch for the buffer. Returns an error in any
other operating mode or attempts to write something other than "1".

28
drivers/hwtracing/intel_th/msu.c
View File

@ -1572,10 +1572,38 @@ free_win:
static DEVICE_ATTR_RW(nr_pages); static DEVICE_ATTR_RW(nr_pages);
static ssize_t
win_switch_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t size)
{
struct msc *msc = dev_get_drvdata(dev);
unsigned long val;
int ret;
ret = kstrtoul(buf, 10, &val);
if (ret)
return ret;
if (val != 1)
return -EINVAL;
mutex_lock(&msc->buf_mutex);
if (msc->mode != MSC_MODE_MULTI)
ret = -ENOTSUPP;
else
ret = intel_th_trace_switch(msc->thdev);
mutex_unlock(&msc->buf_mutex);
return ret ? ret : size;
}
static DEVICE_ATTR_WO(win_switch);
static struct attribute *msc_output_attrs[] = { static struct attribute *msc_output_attrs[] = {
&dev_attr_wrap.attr, &dev_attr_wrap.attr,
&dev_attr_mode.attr, &dev_attr_mode.attr,
&dev_attr_nr_pages.attr, &dev_attr_nr_pages.attr,
&dev_attr_win_switch.attr,
NULL, NULL,
}; };