- Hopefully fix bnc#664105:

Kernel segfault in kernel/timer.c - comm: stapio (process) - related to preloadtrace.ko

OBS-URL: https://build.opensuse.org/package/show/devel:tools/systemtap?expand=0&rev=20

systemtap.changes

@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Fri Jan 14 14:32:11 UTC 2011 - trenn@novell.com
+
+- Hopefully fix bnc#664105:
+  Kernel segfault in kernel/timer.c - comm: stapio (process) - related to preloadtrace.ko
+
 -------------------------------------------------------------------
 Mon Sep 13 11:25:26 UTC 2010 - coolo@novell.com
 

systemtap.spec

@@ -41,6 +41,8 @@ Source:         ftp://sources.redhat.com/pub/systemtap/snapshots/systemtap-%{pac
 Patch1:         systemtap-docdir-fix.diff
 Patch2:         systemtap-hppa.diff
 Patch3:         systemtap-support-2.6.36.diff
+Patch4:         systemtap_improve_gettimeofday_stability.patch
+Patch5:         systemtap_fix_mod_vs_del_timer_race.patch
 
 Requires:       libebl1
 Requires:       %{name}-runtime = %{version}-%{release}
@@ -104,6 +106,8 @@ This package contains the support tools for static probes.
 %patch1 -p1
 %patch2
 %patch3 -p1
+%patch4 -p1
+%patch5 -p1
 
 %build
 autoreconf -fi

systemtap_fix_mod_vs_del_timer_race.patch

@@ -0,0 +1,183 @@
+From: Frank Ch. Eigler <fche@elastic.org>
+Subject: PR10651 / RHBZ653286: mod_timer vs. del_timer_sync races
+References: bnc#664105
+Patch-Mainline: yes
+Git-commit: f2b610b6295628ae1fef744421c293883f1e4298
+Git-repo: git://sources.redhat.com/git/systemtap.git
+
+Signed-off-by: Thomas Renninger <trenn@suse.de>
+
+It appears possible for del_timer_sync (from outside) and mod_timer
+(from within a timer callback) to race.  Defeat this race by ensuring
+that the timer callback checks an atomic_t flag before rescheduling
+itself with mod_timer.
+
+* runtime/transport/relay_v2.c (transport_state): Turn into an atomic_t.
+  Update users.
+  (__stp_relay_wakeup_timer): Observe flag.
+  (_stp_transport_data_fs_{start,stop}): Update flag before timer manipulations.
+* runtime/transport/ring_buffer.c: Ditto for corresponding functions.
+
+diff --git a/runtime/transport/relay_v2.c b/runtime/transport/relay_v2.c
+index 974941d..33e198e 100644
+--- a/runtime/transport/relay_v2.c
++++ b/runtime/transport/relay_v2.c
+@@ -4,7 +4,7 @@
+  * code started as a proposed relayfs interface called 'utt'.  It has
+  * been modified and simplified for systemtap.
+  *
+- * Changes Copyright (C) 2009 Red Hat Inc.
++ * Changes Copyright (C) 2009-2010 Red Hat Inc.
+  *
+  * Original utt code by:
+  *   Copyright (C) 2006 Jens Axboe <axboe@suse.de>
+@@ -42,7 +42,7 @@
+  * to be changed. */
+ struct _stp_relay_data_type {
+ 	struct rchan *rchan;
+-	enum _stp_transport_state transport_state;
++	atomic_t /* enum _stp_transport_state */ transport_state;
+ 	struct dentry *dropped_file;
+ 	atomic_t dropped;
+ 	atomic_t wakeup;
+@@ -133,7 +133,10 @@ static void __stp_relay_wakeup_timer(unsigned long val)
+ #endif
+ 	}
+ 
+- 	mod_timer(&_stp_relay_data.timer, jiffies + STP_RELAY_TIMER_INTERVAL);
++	if (atomic_read(&_stp_relay_data.transport_state) == STP_TRANSPORT_RUNNING)
++        	mod_timer(&_stp_relay_data.timer, jiffies + STP_RELAY_TIMER_INTERVAL);
++        else
++		dbug_trans(0, "relay_v2 wakeup timer expiry\n");
+ }
+ 
+ static void __stp_relay_timer_init(void)
+@@ -149,7 +152,7 @@ static void __stp_relay_timer_init(void)
+ 
+ static enum _stp_transport_state _stp_transport_get_state(void)
+ {
+-	return _stp_relay_data.transport_state;
++	return atomic_read (&_stp_relay_data.transport_state);
+ }
+ 
+ static void _stp_transport_data_fs_overwrite(int overwrite)
+@@ -242,19 +245,19 @@ static struct rchan_callbacks __stp_relay_callbacks = {
+ 
+ static void _stp_transport_data_fs_start(void)
+ {
+-	if (_stp_relay_data.transport_state == STP_TRANSPORT_INITIALIZED) {
++	if (atomic_read (&_stp_relay_data.transport_state) == STP_TRANSPORT_INITIALIZED) {
++		atomic_set (&_stp_relay_data.transport_state, STP_TRANSPORT_RUNNING);
+ 		/* We're initialized.  Now start the timer. */
+ 		__stp_relay_timer_init();
+-		_stp_relay_data.transport_state = STP_TRANSPORT_RUNNING;
+ 	}
+ }
+ 
+ static void _stp_transport_data_fs_stop(void)
+ {
+-	if (_stp_relay_data.transport_state == STP_TRANSPORT_RUNNING) {
++	if (atomic_read (&_stp_relay_data.transport_state) == STP_TRANSPORT_RUNNING) {
++		atomic_set (&_stp_relay_data.transport_state, STP_TRANSPORT_STOPPED);
+ 		del_timer_sync(&_stp_relay_data.timer);
+ 		dbug_trans(0, "flushing...\n");
+-		_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
+ 		if (_stp_relay_data.rchan)
+ 			relay_flush(_stp_relay_data.rchan);
+ 	}
+@@ -277,7 +280,7 @@ static int _stp_transport_data_fs_init(void)
+ 	u64 npages;
+ 	struct sysinfo si;
+ 
+-	_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
++	atomic_set(&_stp_relay_data.transport_state, STP_TRANSPORT_STOPPED);
+ 	_stp_relay_data.overwrite_flag = 0;
+ 	atomic_set(&_stp_relay_data.dropped, 0);
+ 	_stp_relay_data.dropped_file = NULL;
+@@ -337,7 +340,7 @@ static int _stp_transport_data_fs_init(void)
+ 		goto err;
+ 	}
+ 	dbug_trans(1, "returning 0...\n");
+-	_stp_relay_data.transport_state = STP_TRANSPORT_INITIALIZED;
++	atomic_set (&_stp_relay_data.transport_state, STP_TRANSPORT_INITIALIZED);
+ 
+ 	return 0;
+ 
+diff --git a/runtime/transport/ring_buffer.c b/runtime/transport/ring_buffer.c
+index 6c327c0..232f099 100644
+--- a/runtime/transport/ring_buffer.c
++++ b/runtime/transport/ring_buffer.c
+@@ -55,7 +55,7 @@ struct _stp_iterator {
+ #endif
+ 
+ struct _stp_relay_data_type {
+-	enum _stp_transport_state transport_state;
++        atomic_t /* enum _stp_transport_state */ transport_state;
+ 	struct ring_buffer *rb;
+ 	struct _stp_iterator iter[NR_ITERS];
+ 	cpumask_var_t trace_reader_cpumask;
+@@ -649,10 +649,12 @@ static int _stp_data_write_commit(void *entry)
+ 
+ static void __stp_relay_wakeup_timer(unsigned long val)
+ {
+-	if (waitqueue_active(&_stp_poll_wait)
+-	    && ! _stp_ring_buffer_empty())
++	if (waitqueue_active(&_stp_poll_wait) && ! _stp_ring_buffer_empty())
+ 		wake_up_interruptible(&_stp_poll_wait);
+- 	mod_timer(&_stp_relay_data.timer, jiffies + STP_RELAY_TIMER_INTERVAL);
++	if (atomic_read(&_stp_relay_data.transport_state) == STP_TRANSPORT_RUNNING)
++        	mod_timer(&_stp_relay_data.timer, jiffies + STP_RELAY_TIMER_INTERVAL);
++        else
++		dbug_trans(0, "ring_buffer wakeup timer expiry\n");
+ }
+ 
+ static void __stp_relay_timer_start(void)
+@@ -677,7 +679,7 @@ static int _stp_transport_data_fs_init(void)
+ 	int rc;
+ 	int cpu, cpu2;
+ 
+-	_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
++	atomic_set (&_stp_relay_data.transport_state, STP_TRANSPORT_STOPPED);
+ 	_stp_relay_data.rb = NULL;
+ 
+ 	// allocate buffer
+@@ -738,23 +740,23 @@ static int _stp_transport_data_fs_init(void)
+ 	}
+ 
+ 	dbug_trans(1, "returning 0...\n");
+-	_stp_relay_data.transport_state = STP_TRANSPORT_INITIALIZED;
++	atomic_set (&_stp_relay_data.transport_state, STP_TRANSPORT_INITIALIZED);
+ 	return 0;
+ }
+ 
+ static void _stp_transport_data_fs_start(void)
+ {
+-	if (_stp_relay_data.transport_state == STP_TRANSPORT_INITIALIZED) {
+-		__stp_relay_timer_start();
+-		_stp_relay_data.transport_state = STP_TRANSPORT_RUNNING;
++	if (atomic_read(&_stp_relay_data.transport_state) == STP_TRANSPORT_INITIALIZED) {
++        	atomic_set(&_stp_relay_data.transport_state, STP_TRANSPORT_RUNNING);
++                __stp_relay_timer_start();
+ 	}
+ }
+ 
+ static void _stp_transport_data_fs_stop(void)
+ {
+-	if (_stp_relay_data.transport_state == STP_TRANSPORT_RUNNING) {
+-		__stp_relay_timer_stop();
+-		_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
++	if (atomic_read(&_stp_relay_data.transport_state) == STP_TRANSPORT_RUNNING) {
++        	atomic_set(&_stp_relay_data.transport_state, STP_TRANSPORT_STOPPED);
++                __stp_relay_timer_stop();
+ 	}
+ }
+ 
+@@ -773,7 +775,7 @@ static void _stp_transport_data_fs_close(void)
+ 
+ static enum _stp_transport_state _stp_transport_get_state(void)
+ {
+-	return _stp_relay_data.transport_state;
++	return atomic_read (&_stp_relay_data.transport_state);
+ }
+ 
+ static void _stp_transport_data_fs_overwrite(int overwrite)

systemtap_improve_gettimeofday_stability.patch

@@ -0,0 +1,141 @@
+From: Josh Stone <jistone@redhat.com>
+Subject: Improve gettimeofday stability
+References: bnc#664105
+Patch-Mainline: yes
+Git-commit: 3fd1c4901e81e5f6b550bb988d612281e0fc231b
+Git-repo: git://sources.redhat.com/git/systemtap.git
+
+Signed-off-by: Thomas Renninger <trenn@suse.de>
+
+These are a few tweaks to improve the stability of our gettimeofday
+startup and shutdown.  Hopefully this helps with PR10651 and PR12182,
+but that's not been confirmed yet.
+
+* runtime/runtime.h: Don't include time.c here.
+* translate.cxx (c_unparser::emit_common_header): Include time.c here,
+  only if NEEDed (so we also ensure init/kill_time will be called).
+  (c_unparser::emit_module_init): Change to STAP_SESSION_STOPPED for the
+  final cleanup efforts, especially for time.c to wrap up.
+  (c_unparser::emit_module_exit): Ditto.
+* runtime/time.c (__stp_time_timer_callback): Use the session_state
+  instead of stp_timer_reregister, and continue until STOPPED.
+  (__stp_init_time): Don't add_timer from the IPI.
+  (_stp_init_time): Instead, add_timer_on each cpu here.
+
+diff --git a/runtime/runtime.h b/runtime/runtime.h
+index d4f41db..814d8ad 100644
+--- a/runtime/runtime.h
++++ b/runtime/runtime.h
+@@ -132,7 +132,6 @@ static struct
+ #include "copy.c"
+ #include "regs.c"
+ #include "regs-ia64.c"
+-#include "time.c"
+ 
+ #include "task_finder.c"
+ 
+diff --git a/runtime/time.c b/runtime/time.c
+index 0d13487..38a808a 100644
+--- a/runtime/time.c
++++ b/runtime/time.c
+@@ -56,9 +56,6 @@ typedef struct __stp_time_t {
+ 
+ static void *stp_time = NULL;
+ 
+-/* Flag to tell the timer callback whether to reregister */
+-static int stp_timer_reregister = 0;
+-
+ /* Try to estimate the number of CPU cycles in a millisecond - i.e. kHz.  This
+  * relies heavily on the accuracy of udelay.  By calling udelay twice, we
+  * attempt to account for overhead in the call.
+@@ -134,7 +131,7 @@ __stp_time_timer_callback(unsigned long val)
+        XXX: The worst that can probably happen is that we get
+ 	    two consecutive timer resets.  */
+ 
+-    if (likely(stp_timer_reregister))
++    if (likely(atomic_read(&session_state) != STAP_SESSION_STOPPED))
+         mod_timer(&time->timer, jiffies + 1);
+ }
+ 
+@@ -154,7 +151,6 @@ __stp_init_time(void *info)
+     init_timer(&time->timer);
+     time->timer.expires = jiffies + 1;
+     time->timer.function = __stp_time_timer_callback;
+-    add_timer(&time->timer);
+ }
+ 
+ #ifdef CONFIG_CPU_FREQ
+@@ -208,7 +204,6 @@ _stp_kill_time(void)
+ {
+     if (stp_time) {
+         int cpu;
+-        stp_timer_reregister = 0;
+         for_each_online_cpu(cpu) {
+             stp_time_t *time = per_cpu_ptr(stp_time, cpu);
+             del_timer_sync(&time->timer);
+@@ -229,20 +224,23 @@ _stp_kill_time(void)
+ static int
+ _stp_init_time(void)
+ {
+-    int ret = 0;
++    int cpu, ret = 0;
+ 
+     _stp_kill_time();
+ 
+     stp_time = _stp_alloc_percpu(sizeof(stp_time_t));
+     if (unlikely(stp_time == 0))
+ 	    return -1;
+-    
+-    stp_timer_reregister = 1;
++
+ #ifdef STAPCONF_ONEACHCPU_RETRY
+     ret = on_each_cpu(__stp_init_time, NULL, 0, 1);
+ #else
+     ret = on_each_cpu(__stp_init_time, NULL, 1);
+ #endif
++    for_each_online_cpu(cpu) {
++        stp_time_t *time = per_cpu_ptr(stp_time, cpu);
++        add_timer_on(&time->timer, cpu);
++    }
+ 
+ #ifdef CONFIG_CPU_FREQ
+     if (!ret && !__stp_constant_freq()) {
+@@ -250,7 +248,6 @@ _stp_init_time(void)
+                 CPUFREQ_TRANSITION_NOTIFIER);
+ 
+         if (!ret) {
+-            int cpu;
+             for_each_online_cpu(cpu) {
+                 unsigned long flags;
+                 int freq_khz = cpufreq_get(cpu);
+diff --git a/translate.cxx b/translate.cxx
+index f360940..4447a24 100644
+--- a/translate.cxx
++++ b/translate.cxx
+@@ -1085,6 +1085,10 @@ c_unparser::emit_common_header ()
+   if (!session->stat_decls.empty())
+     o->newline() << "#include \"stat.c\"\n";
+ 
++  o->newline() << "#ifdef STAP_NEED_GETTIMEOFDAY";
++  o->newline() << "#include \"time.c\"";  // Don't we all need more?
++  o->newline() << "#endif";
++
+   o->newline();
+ }
+ 
+@@ -1327,6 +1331,7 @@ c_unparser::emit_module_init ()
+     }
+ 
+   // For any partially registered/unregistered kernel facilities.
++  o->newline() << "atomic_set (&session_state, STAP_SESSION_STOPPED);";
+   o->newline() << "#ifdef STAPCONF_SYNCHRONIZE_SCHED";
+   o->newline() << "synchronize_sched();";
+   o->newline() << "#endif";
+@@ -1409,6 +1414,7 @@ c_unparser::emit_module_exit ()
+   o->newline(-2) << "} while (holdon);";
+ 
+   // cargo cult epilogue
++  o->newline() << "atomic_set (&session_state, STAP_SESSION_STOPPED);";
+   o->newline() << "#ifdef STAPCONF_SYNCHRONIZE_SCHED";
+   o->newline() << "synchronize_sched();";
+   o->newline() << "#endif";