Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 351 insertions, 0 deletions

diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c
new file mode 100644
index 000000000..4ab05e105
--- /dev/null
+++ b/drivers/rtc/sysfs.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RTC subsystem, sysfs interface
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ */
+
+#include <linux/kstrtox.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+
+#include "rtc-core.h"
+
+/* device attributes */
+
+/*
+ * NOTE:  RTC times displayed in sysfs use the RTC's timezone.  That's
+ * ideally UTC.  However, PCs that also boot to MS-Windows normally use
+ * the local time and change to match daylight savings time.  That affects
+ * attributes including date, time, since_epoch, and wakealarm.
+ */
+
+static ssize_t
+name_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%s %s\n", dev_driver_string(dev->parent),
+			  dev_name(dev->parent));
+}
+static DEVICE_ATTR_RO(name);
+
+static ssize_t
+date_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	ssize_t retval;
+	struct rtc_time tm;
+
+	retval = rtc_read_time(to_rtc_device(dev), &tm);
+	if (retval)
+		return retval;
+
+	return sysfs_emit(buf, "%ptRd\n", &tm);
+}
+static DEVICE_ATTR_RO(date);
+
+static ssize_t
+time_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	ssize_t retval;
+	struct rtc_time tm;
+
+	retval = rtc_read_time(to_rtc_device(dev), &tm);
+	if (retval)
+		return retval;
+
+	return sysfs_emit(buf, "%ptRt\n", &tm);
+}
+static DEVICE_ATTR_RO(time);
+
+static ssize_t
+since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	ssize_t retval;
+	struct rtc_time tm;
+
+	retval = rtc_read_time(to_rtc_device(dev), &tm);
+	if (retval)
+		return retval;
+
+	return sysfs_emit(buf, "%lld\n", rtc_tm_to_time64(&tm));
+}
+static DEVICE_ATTR_RO(since_epoch);
+
+static ssize_t
+max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
+}
+
+static ssize_t
+max_user_freq_store(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t n)
+{
+	struct rtc_device *rtc = to_rtc_device(dev);
+	unsigned long val;
+	int err;
+
+	err = kstrtoul(buf, 0, &val);
+	if (err)
+		return err;
+
+	if (val >= 4096 || val == 0)
+		return -EINVAL;
+
+	rtc->max_user_freq = (int)val;
+
+	return n;
+}
+static DEVICE_ATTR_RW(max_user_freq);
+
+/**
+ * hctosys_show - indicate if the given RTC set the system time
+ * @dev: The device that the attribute belongs to.
+ * @attr: The attribute being read.
+ * @buf: The result buffer.
+ *
+ * buf is "1" if the system clock was set by this RTC at the last
+ * boot or resume event.
+ */
+static ssize_t
+hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+#ifdef CONFIG_RTC_HCTOSYS_DEVICE
+	if (rtc_hctosys_ret == 0 &&
+	    strcmp(dev_name(&to_rtc_device(dev)->dev),
+		   CONFIG_RTC_HCTOSYS_DEVICE) == 0)
+		return sysfs_emit(buf, "1\n");
+#endif
+	return sysfs_emit(buf, "0\n");
+}
+static DEVICE_ATTR_RO(hctosys);
+
+static ssize_t
+wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	ssize_t retval;
+	struct rtc_wkalrm alm;
+
+	/* Don't show disabled alarms.  For uniformity, RTC alarms are
+	 * conceptually one-shot, even though some common RTCs (on PCs)
+	 * don't actually work that way.
+	 *
+	 * NOTE: RTC implementations where the alarm doesn't match an
+	 * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
+	 * alarms after they trigger, to ensure one-shot semantics.
+	 */
+	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
+	if (retval)
+		return retval;
+
+	if (alm.enabled)
+		return sysfs_emit(buf, "%lld\n", rtc_tm_to_time64(&alm.time));
+
+	return 0;
+}
+
+static ssize_t
+wakealarm_store(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t n)
+{
+	ssize_t retval;
+	time64_t now, alarm;
+	time64_t push = 0;
+	struct rtc_wkalrm alm;
+	struct rtc_device *rtc = to_rtc_device(dev);
+	const char *buf_ptr;
+	int adjust = 0;
+
+	/* Only request alarms that trigger in the future.  Disable them
+	 * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
+	 */
+	retval = rtc_read_time(rtc, &alm.time);
+	if (retval < 0)
+		return retval;
+	now = rtc_tm_to_time64(&alm.time);
+
+	buf_ptr = buf;
+	if (*buf_ptr == '+') {
+		buf_ptr++;
+		if (*buf_ptr == '=') {
+			buf_ptr++;
+			push = 1;
+		} else {
+			adjust = 1;
+		}
+	}
+	retval = kstrtos64(buf_ptr, 0, &alarm);
+	if (retval)
+		return retval;
+	if (adjust)
+		alarm += now;
+	if (alarm > now || push) {
+		/* Avoid accidentally clobbering active alarms; we can't
+		 * entirely prevent that here, without even the minimal
+		 * locking from the /dev/rtcN api.
+		 */
+		retval = rtc_read_alarm(rtc, &alm);
+		if (retval < 0)
+			return retval;
+		if (alm.enabled) {
+			if (push) {
+				push = rtc_tm_to_time64(&alm.time);
+				alarm += push;
+			} else
+				return -EBUSY;
+		} else if (push)
+			return -EINVAL;
+		alm.enabled = 1;
+	} else {
+		alm.enabled = 0;
+
+		/* Provide a valid future alarm time.  Linux isn't EFI,
+		 * this time won't be ignored when disabling the alarm.
+		 */
+		alarm = now + 300;
+	}
+	rtc_time64_to_tm(alarm, &alm.time);
+
+	retval = rtc_set_alarm(rtc, &alm);
+	return (retval < 0) ? retval : n;
+}
+static DEVICE_ATTR_RW(wakealarm);
+
+static ssize_t
+offset_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	ssize_t retval;
+	long offset;
+
+	retval = rtc_read_offset(to_rtc_device(dev), &offset);
+	if (retval)
+		return retval;
+
+	return sysfs_emit(buf, "%ld\n", offset);
+}
+
+static ssize_t
+offset_store(struct device *dev, struct device_attribute *attr,
+	     const char *buf, size_t n)
+{
+	ssize_t retval;
+	long offset;
+
+	retval = kstrtol(buf, 10, &offset);
+	if (retval == 0)
+		retval = rtc_set_offset(to_rtc_device(dev), offset);
+
+	return (retval < 0) ? retval : n;
+}
+static DEVICE_ATTR_RW(offset);
+
+static ssize_t
+range_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
+			  to_rtc_device(dev)->range_max);
+}
+static DEVICE_ATTR_RO(range);
+
+static struct attribute *rtc_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_date.attr,
+	&dev_attr_time.attr,
+	&dev_attr_since_epoch.attr,
+	&dev_attr_max_user_freq.attr,
+	&dev_attr_hctosys.attr,
+	&dev_attr_wakealarm.attr,
+	&dev_attr_offset.attr,
+	&dev_attr_range.attr,
+	NULL,
+};
+
+/* The reason to trigger an alarm with no process watching it (via sysfs)
+ * is its side effect:  waking from a system state like suspend-to-RAM or
+ * suspend-to-disk.  So: no attribute unless that side effect is possible.
+ * (Userspace may disable that mechanism later.)
+ */
+static bool rtc_does_wakealarm(struct rtc_device *rtc)
+{
+	if (!device_can_wakeup(rtc->dev.parent))
+		return false;
+
+	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);
+}
+
+static umode_t rtc_attr_is_visible(struct kobject *kobj,
+				   struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct rtc_device *rtc = to_rtc_device(dev);
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_wakealarm.attr) {
+		if (!rtc_does_wakealarm(rtc))
+			mode = 0;
+	} else if (attr == &dev_attr_offset.attr) {
+		if (!rtc->ops->set_offset)
+			mode = 0;
+	} else if (attr == &dev_attr_range.attr) {
+		if (!(rtc->range_max - rtc->range_min))
+			mode = 0;
+	}
+
+	return mode;
+}
+
+static struct attribute_group rtc_attr_group = {
+	.is_visible	= rtc_attr_is_visible,
+	.attrs		= rtc_attrs,
+};
+__ATTRIBUTE_GROUPS(rtc_attr);
+
+const struct attribute_group **rtc_get_dev_attribute_groups(void)
+{
+	return rtc_attr_groups;
+}
+
+int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)
+{
+	size_t old_cnt = 0, add_cnt = 0, new_cnt;
+	const struct attribute_group **groups, **old;
+
+	if (grps) {
+		for (groups = grps; *groups; groups++)
+			add_cnt++;
+		/* No need to modify current groups if nothing new is provided */
+		if (add_cnt == 0)
+			return 0;
+	} else {
+		return -EINVAL;
+	}
+
+	groups = rtc->dev.groups;
+	if (groups)
+		for (; *groups; groups++)
+			old_cnt++;
+
+	new_cnt = old_cnt + add_cnt + 1;
+	groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);
+	if (!groups)
+		return -ENOMEM;
+	memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));
+	memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));
+	groups[old_cnt + add_cnt] = NULL;
+
+	old = rtc->dev.groups;
+	rtc->dev.groups = groups;
+	if (old && old != rtc_attr_groups)
+		devm_kfree(&rtc->dev, old);
+
+	return 0;
+}
+EXPORT_SYMBOL(rtc_add_groups);
+
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+	const struct attribute_group *groups[] = { grp, NULL };
+
+	return rtc_add_groups(rtc, groups);
+}
+EXPORT_SYMBOL(rtc_add_group);