Revision f17a5194859a82afe4164e938b92035b86c55794 authored by Steven Rostedt (Red Hat) on 31 May 2013, 01:10:37 UTC, committed by Steven Rostedt on 06 June 2013, 16:35:30 UTC
The irqsoff tracer records the max time that interrupts are disabled. There are hooks in the assembly code that calls back into the tracer when interrupts are disabled or enabled. When they are enabled, the tracer checks if the amount of time they were disabled is larger than the previous recorded max interrupts off time. If it is, it creates a snapshot of the currently running trace to store where the last largest interrupts off time was held and how it happened. During testing, this RCU lockdep dump appeared: [ 1257.829021] =============================== [ 1257.829021] [ INFO: suspicious RCU usage. ] [ 1257.829021] 3.10.0-rc1-test+ #171 Tainted: G W [ 1257.829021] ------------------------------- [ 1257.829021] /home/rostedt/work/git/linux-trace.git/include/linux/rcupdate.h:780 rcu_read_lock() used illegally while idle! [ 1257.829021] [ 1257.829021] other info that might help us debug this: [ 1257.829021] [ 1257.829021] [ 1257.829021] RCU used illegally from idle CPU! [ 1257.829021] rcu_scheduler_active = 1, debug_locks = 0 [ 1257.829021] RCU used illegally from extended quiescent state! [ 1257.829021] 2 locks held by trace-cmd/4831: [ 1257.829021] #0: (max_trace_lock){......}, at: [<ffffffff810e2b77>] stop_critical_timing+0x1a3/0x209 [ 1257.829021] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff810dae5a>] __update_max_tr+0x88/0x1ee [ 1257.829021] [ 1257.829021] stack backtrace: [ 1257.829021] CPU: 3 PID: 4831 Comm: trace-cmd Tainted: G W 3.10.0-rc1-test+ #171 [ 1257.829021] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 [ 1257.829021] 0000000000000001 ffff880065f49da8 ffffffff8153dd2b ffff880065f49dd8 [ 1257.829021] ffffffff81092a00 ffff88006bd78680 ffff88007add7500 0000000000000003 [ 1257.829021] ffff88006bd78680 ffff880065f49e18 ffffffff810daebf ffffffff810dae5a [ 1257.829021] Call Trace: [ 1257.829021] [<ffffffff8153dd2b>] dump_stack+0x19/0x1b [ 1257.829021] [<ffffffff81092a00>] lockdep_rcu_suspicious+0x109/0x112 [ 1257.829021] [<ffffffff810daebf>] __update_max_tr+0xed/0x1ee [ 1257.829021] [<ffffffff810dae5a>] ? __update_max_tr+0x88/0x1ee [ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107 [ 1257.829021] [<ffffffff810dbf85>] update_max_tr_single+0x11d/0x12d [ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107 [ 1257.829021] [<ffffffff810e2b15>] stop_critical_timing+0x141/0x209 [ 1257.829021] [<ffffffff8109569a>] ? trace_hardirqs_on+0xd/0xf [ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107 [ 1257.829021] [<ffffffff810e3057>] time_hardirqs_on+0x2a/0x2f [ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107 [ 1257.829021] [<ffffffff8109550c>] trace_hardirqs_on_caller+0x16/0x197 [ 1257.829021] [<ffffffff8109569a>] trace_hardirqs_on+0xd/0xf [ 1257.829021] [<ffffffff811002b9>] user_enter+0xfd/0x107 [ 1257.829021] [<ffffffff810029b4>] do_notify_resume+0x92/0x97 [ 1257.829021] [<ffffffff8154bdca>] int_signal+0x12/0x17 What happened was entering into the user code, the interrupts were enabled and a max interrupts off was recorded. The trace buffer was saved along with various information about the task: comm, pid, uid, priority, etc. The uid is recorded with task_uid(tsk). But this is a macro that uses rcu_read_lock() to retrieve the data, and this happened to happen where RCU is blind (user_enter). As only the preempt and irqs off tracers can have this happen, and they both only have the tsk == current, if tsk == current, use current_uid() instead of task_uid(), as current_uid() does not use RCU as only current can change its uid. This fixes the RCU suspicious splat. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 parent 0184d50
qconf.h
/*
* Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
* Released under the terms of the GNU GPL v2.0.
*/
#if QT_VERSION < 0x040000
#include <qlistview.h>
#else
#include <q3listview.h>
#endif
#include <qsettings.h>
#if QT_VERSION < 0x040000
#define Q3ValueList QValueList
#define Q3PopupMenu QPopupMenu
#define Q3ListView QListView
#define Q3ListViewItem QListViewItem
#define Q3VBox QVBox
#define Q3TextBrowser QTextBrowser
#define Q3MainWindow QMainWindow
#define Q3Action QAction
#define Q3ToolBar QToolBar
#define Q3ListViewItemIterator QListViewItemIterator
#define Q3FileDialog QFileDialog
#endif
class ConfigView;
class ConfigList;
class ConfigItem;
class ConfigLineEdit;
class ConfigMainWindow;
class ConfigSettings : public QSettings {
public:
Q3ValueList<int> readSizes(const QString& key, bool *ok);
bool writeSizes(const QString& key, const Q3ValueList<int>& value);
};
enum colIdx {
promptColIdx, nameColIdx, noColIdx, modColIdx, yesColIdx, dataColIdx, colNr
};
enum listMode {
singleMode, menuMode, symbolMode, fullMode, listMode
};
enum optionMode {
normalOpt = 0, allOpt, promptOpt
};
class ConfigList : public Q3ListView {
Q_OBJECT
typedef class Q3ListView Parent;
public:
ConfigList(ConfigView* p, const char *name = 0);
void reinit(void);
ConfigView* parent(void) const
{
return (ConfigView*)Parent::parent();
}
ConfigItem* findConfigItem(struct menu *);
protected:
void keyPressEvent(QKeyEvent *e);
void contentsMousePressEvent(QMouseEvent *e);
void contentsMouseReleaseEvent(QMouseEvent *e);
void contentsMouseMoveEvent(QMouseEvent *e);
void contentsMouseDoubleClickEvent(QMouseEvent *e);
void focusInEvent(QFocusEvent *e);
void contextMenuEvent(QContextMenuEvent *e);
public slots:
void setRootMenu(struct menu *menu);
void updateList(ConfigItem *item);
void setValue(ConfigItem* item, tristate val);
void changeValue(ConfigItem* item);
void updateSelection(void);
void saveSettings(void);
signals:
void menuChanged(struct menu *menu);
void menuSelected(struct menu *menu);
void parentSelected(void);
void gotFocus(struct menu *);
public:
void updateListAll(void)
{
updateAll = true;
updateList(NULL);
updateAll = false;
}
ConfigList* listView()
{
return this;
}
ConfigItem* firstChild() const
{
return (ConfigItem *)Parent::firstChild();
}
int mapIdx(colIdx idx)
{
return colMap[idx];
}
void addColumn(colIdx idx, const QString& label)
{
colMap[idx] = Parent::addColumn(label);
colRevMap[colMap[idx]] = idx;
}
void removeColumn(colIdx idx)
{
int col = colMap[idx];
if (col >= 0) {
Parent::removeColumn(col);
colRevMap[col] = colMap[idx] = -1;
}
}
void setAllOpen(bool open);
void setParentMenu(void);
bool menuSkip(struct menu *);
template <class P>
void updateMenuList(P*, struct menu*);
bool updateAll;
QPixmap symbolYesPix, symbolModPix, symbolNoPix;
QPixmap choiceYesPix, choiceNoPix;
QPixmap menuPix, menuInvPix, menuBackPix, voidPix;
bool showName, showRange, showData;
enum listMode mode;
enum optionMode optMode;
struct menu *rootEntry;
QColorGroup disabledColorGroup;
QColorGroup inactivedColorGroup;
Q3PopupMenu* headerPopup;
private:
int colMap[colNr];
int colRevMap[colNr];
};
class ConfigItem : public Q3ListViewItem {
typedef class Q3ListViewItem Parent;
public:
ConfigItem(Q3ListView *parent, ConfigItem *after, struct menu *m, bool v)
: Parent(parent, after), menu(m), visible(v), goParent(false)
{
init();
}
ConfigItem(ConfigItem *parent, ConfigItem *after, struct menu *m, bool v)
: Parent(parent, after), menu(m), visible(v), goParent(false)
{
init();
}
ConfigItem(Q3ListView *parent, ConfigItem *after, bool v)
: Parent(parent, after), menu(0), visible(v), goParent(true)
{
init();
}
~ConfigItem(void);
void init(void);
void okRename(int col);
void updateMenu(void);
void testUpdateMenu(bool v);
ConfigList* listView() const
{
return (ConfigList*)Parent::listView();
}
ConfigItem* firstChild() const
{
return (ConfigItem *)Parent::firstChild();
}
ConfigItem* nextSibling() const
{
return (ConfigItem *)Parent::nextSibling();
}
void setText(colIdx idx, const QString& text)
{
Parent::setText(listView()->mapIdx(idx), text);
}
QString text(colIdx idx) const
{
return Parent::text(listView()->mapIdx(idx));
}
void setPixmap(colIdx idx, const QPixmap& pm)
{
Parent::setPixmap(listView()->mapIdx(idx), pm);
}
const QPixmap* pixmap(colIdx idx) const
{
return Parent::pixmap(listView()->mapIdx(idx));
}
void paintCell(QPainter* p, const QColorGroup& cg, int column, int width, int align);
ConfigItem* nextItem;
struct menu *menu;
bool visible;
bool goParent;
};
class ConfigLineEdit : public QLineEdit {
Q_OBJECT
typedef class QLineEdit Parent;
public:
ConfigLineEdit(ConfigView* parent);
ConfigView* parent(void) const
{
return (ConfigView*)Parent::parent();
}
void show(ConfigItem *i);
void keyPressEvent(QKeyEvent *e);
public:
ConfigItem *item;
};
class ConfigView : public Q3VBox {
Q_OBJECT
typedef class Q3VBox Parent;
public:
ConfigView(QWidget* parent, const char *name = 0);
~ConfigView(void);
static void updateList(ConfigItem* item);
static void updateListAll(void);
bool showName(void) const { return list->showName; }
bool showRange(void) const { return list->showRange; }
bool showData(void) const { return list->showData; }
public slots:
void setShowName(bool);
void setShowRange(bool);
void setShowData(bool);
void setOptionMode(QAction *);
signals:
void showNameChanged(bool);
void showRangeChanged(bool);
void showDataChanged(bool);
public:
ConfigList* list;
ConfigLineEdit* lineEdit;
static ConfigView* viewList;
ConfigView* nextView;
static QAction *showNormalAction;
static QAction *showAllAction;
static QAction *showPromptAction;
};
class ConfigInfoView : public Q3TextBrowser {
Q_OBJECT
typedef class Q3TextBrowser Parent;
public:
ConfigInfoView(QWidget* parent, const char *name = 0);
bool showDebug(void) const { return _showDebug; }
public slots:
void setInfo(struct menu *menu);
void saveSettings(void);
void setShowDebug(bool);
signals:
void showDebugChanged(bool);
void menuSelected(struct menu *);
protected:
void symbolInfo(void);
void menuInfo(void);
QString debug_info(struct symbol *sym);
static QString print_filter(const QString &str);
static void expr_print_help(void *data, struct symbol *sym, const char *str);
Q3PopupMenu* createPopupMenu(const QPoint& pos);
void contentsContextMenuEvent(QContextMenuEvent *e);
struct symbol *sym;
struct menu *_menu;
bool _showDebug;
};
class ConfigSearchWindow : public QDialog {
Q_OBJECT
typedef class QDialog Parent;
public:
ConfigSearchWindow(ConfigMainWindow* parent, const char *name = 0);
public slots:
void saveSettings(void);
void search(void);
protected:
QLineEdit* editField;
QPushButton* searchButton;
QSplitter* split;
ConfigView* list;
ConfigInfoView* info;
struct symbol **result;
};
class ConfigMainWindow : public Q3MainWindow {
Q_OBJECT
static Q3Action *saveAction;
static void conf_changed(void);
public:
ConfigMainWindow(void);
public slots:
void changeMenu(struct menu *);
void setMenuLink(struct menu *);
void listFocusChanged(void);
void goBack(void);
void loadConfig(void);
bool saveConfig(void);
void saveConfigAs(void);
void searchConfig(void);
void showSingleView(void);
void showSplitView(void);
void showFullView(void);
void showIntro(void);
void showAbout(void);
void saveSettings(void);
protected:
void closeEvent(QCloseEvent *e);
ConfigSearchWindow *searchWindow;
ConfigView *menuView;
ConfigList *menuList;
ConfigView *configView;
ConfigList *configList;
ConfigInfoView *helpText;
Q3ToolBar *toolBar;
Q3Action *backAction;
QSplitter* split1;
QSplitter* split2;
};
![swh spinner](/static/img/swh-spinner.gif)
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