---

yaml
---
r: 279695
b: refs/heads/master
c: e4e88f3
h: refs/heads/master
i:
  279693: a708155
  279691: cf452c7
  279687: d25aa2e
  279679: 5cbd587
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ef88e3911c0e0301e73fa3b3b2567aabdbe17cc4
+refs/heads/master: e4e88f31bcb5f05f24b9ae518d4ecb44e1a7774d

trunk/CREDITS

@@ -688,10 +688,13 @@ S: Oxfordshire, UK.
 
 N: Kees Cook
 E: kees@outflux.net
-W: http://outflux.net/
-P: 1024D/17063E6D 9FA3 C49C 23C9 D1BC 2E30  1975 1FFF 4BA9 1706 3E6D
-D: Minor updates to SCSI types, added /proc/pid/maps protection
+E: kees@ubuntu.com
+E: keescook@chromium.org
+W: http://outflux.net/blog/
+P: 4096R/DC6DC026 A5C3 F68F 229D D60F 723E  6E13 8972 F4DF DC6D C026
+D: Various security things, bug fixes, and documentation.
 S: (ask for current address)
+S: Portland, Oregon
 S: USA
 
 N: Robin Cornelius

trunk/Documentation/ABI/testing/sysfs-bus-rbd

@@ -57,13 +57,6 @@ create_snap
 
 	 $ echo <snap-name> > /sys/bus/rbd/devices/<dev-id>/snap_create
 
-rollback_snap
-
-	Rolls back data to the specified snapshot. This goes over the entire
-	list of rados blocks and sends a rollback command to each.
-
-	 $ echo <snap-name> > /sys/bus/rbd/devices/<dev-id>/snap_rollback
-
 snap_*
 
 	A directory per each snapshot

trunk/Documentation/DocBook/debugobjects.tmpl

@@ -96,6 +96,7 @@
 	<listitem><para>debug_object_deactivate</para></listitem>
 	<listitem><para>debug_object_destroy</para></listitem>
 	<listitem><para>debug_object_free</para></listitem>
+	<listitem><para>debug_object_assert_init</para></listitem>
       </itemizedlist>
       Each of these functions takes the address of the real object and
       a pointer to the object type specific debug description
@@ -273,6 +274,26 @@
 	debug checks.
       </para>
     </sect1>
+
+    <sect1 id="debug_object_assert_init">
+      <title>debug_object_assert_init</title>
+      <para>
+	This function is called to assert that an object has been
+	initialized.
+      </para>
+      <para>
+	When the real object is not tracked by debugobjects, it calls
+	fixup_assert_init of the object type description structure
+	provided by the caller, with the hardcoded object state
+	ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem
+	by calling debug_object_init and other specific initializing
+	functions.
+      </para>
+      <para>
+	When the real object is already tracked by debugobjects it is
+	ignored.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="fixupfunctions">
     <title>Fixup functions</title>
@@ -381,6 +402,35 @@
 	statistics.
       </para>
     </sect1>
+    <sect1 id="fixup_assert_init">
+      <title>fixup_assert_init</title>
+      <para>
+	This function is called from the debug code whenever a problem
+	in debug_object_assert_init is detected.
+      </para>
+      <para>
+	Called from debug_object_assert_init() with a hardcoded state
+	ODEBUG_STATE_NOTAVAILABLE when the object is not found in the
+	debug bucket.
+      </para>
+      <para>
+	The function returns 1 when the fixup was successful,
+	otherwise 0. The return value is used to update the
+	statistics.
+      </para>
+      <para>
+	Note, this function should make sure debug_object_init() is
+	called before returning.
+      </para>
+      <para>
+	The handling of statically initialized objects is a special
+	case. The fixup function should check if this is a legitimate
+	case of a statically initialized object or not. In this case only
+	debug_object_init() should be called to make the object known to
+	the tracker. Then the function should return 0 because this is not
+	a real fixup.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="bugs">
     <title>Known Bugs And Assumptions</title>

trunk/Documentation/RCU/checklist.txt

@@ -328,6 +328,12 @@ over a rather long period of time, but improvements are always welcome!
 	RCU rather than SRCU, because RCU is almost always faster and
 	easier to use than is SRCU.
 
+	If you need to enter your read-side critical section in a
+	hardirq or exception handler, and then exit that same read-side
+	critical section in the task that was interrupted, then you need
+	to srcu_read_lock_raw() and srcu_read_unlock_raw(), which avoid
+	the lockdep checking that would otherwise this practice illegal.
+
 	Also unlike other forms of RCU, explicit initialization
 	and cleanup is required via init_srcu_struct() and
 	cleanup_srcu_struct().	These are passed a "struct srcu_struct"

trunk/Documentation/RCU/rcu.txt

@@ -38,11 +38,11 @@ o	How can the updater tell when a grace period has completed
 
 	Preemptible variants of RCU (CONFIG_TREE_PREEMPT_RCU) get the
 	same effect, but require that the readers manipulate CPU-local
-	counters.  These counters allow limited types of blocking
-	within RCU read-side critical sections.  SRCU also uses
-	CPU-local counters, and permits general blocking within
-	RCU read-side critical sections.  These two variants of
-	RCU detect grace periods by sampling these counters.
+	counters.  These counters allow limited types of blocking within
+	RCU read-side critical sections.  SRCU also uses CPU-local
+	counters, and permits general blocking within RCU read-side
+	critical sections.  These variants of RCU detect grace periods
+	by sampling these counters.
 
 o	If I am running on a uniprocessor kernel, which can only do one
 	thing at a time, why should I wait for a grace period?

trunk/Documentation/RCU/stallwarn.txt

@@ -101,6 +101,11 @@ o	A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that
 	CONFIG_TREE_PREEMPT_RCU case, you might see stall-warning
 	messages.
 
+o	A hardware or software issue shuts off the scheduler-clock
+	interrupt on a CPU that is not in dyntick-idle mode.  This
+	problem really has happened, and seems to be most likely to
+	result in RCU CPU stall warnings for CONFIG_NO_HZ=n kernels.
+
 o	A bug in the RCU implementation.
 
 o	A hardware failure.  This is quite unlikely, but has occurred
@@ -109,12 +114,11 @@ o	A hardware failure.  This is quite unlikely, but has occurred
 	This resulted in a series of RCU CPU stall warnings, eventually
 	leading the realization that the CPU had failed.
 
-The RCU, RCU-sched, and RCU-bh implementations have CPU stall
-warning.  SRCU does not have its own CPU stall warnings, but its
-calls to synchronize_sched() will result in RCU-sched detecting
-RCU-sched-related CPU stalls.  Please note that RCU only detects
-CPU stalls when there is a grace period in progress.  No grace period,
-no CPU stall warnings.
+The RCU, RCU-sched, and RCU-bh implementations have CPU stall warning.
+SRCU does not have its own CPU stall warnings, but its calls to
+synchronize_sched() will result in RCU-sched detecting RCU-sched-related
+CPU stalls.  Please note that RCU only detects CPU stalls when there is
+a grace period in progress.  No grace period, no CPU stall warnings.
 
 To diagnose the cause of the stall, inspect the stack traces.
 The offending function will usually be near the top of the stack.

trunk/Documentation/RCU/torture.txt

@@ -61,11 +61,24 @@ nreaders	This is the number of RCU reading threads supported.
 		To properly exercise RCU implementations with preemptible
 		read-side critical sections.
 
+onoff_interval
+		The number of seconds between each attempt to execute a
+		randomly selected CPU-hotplug operation.  Defaults to
+		zero, which disables CPU hotplugging.  In HOTPLUG_CPU=n
+		kernels, rcutorture will silently refuse to do any
+		CPU-hotplug operations regardless of what value is
+		specified for onoff_interval.
+
 shuffle_interval
 		The number of seconds to keep the test threads affinitied
 		to a particular subset of the CPUs, defaults to 3 seconds.
 		Used in conjunction with test_no_idle_hz.
 
+shutdown_secs	The number of seconds to run the test before terminating
+		the test and powering off the system.  The default is
+		zero, which disables test termination and system shutdown.
+		This capability is useful for automated testing.
+
 stat_interval	The number of seconds between output of torture
 		statistics (via printk()).  Regardless of the interval,
 		statistics are printed when the module is unloaded.

trunk/Documentation/RCU/trace.txt

@@ -105,14 +105,10 @@ o	"dt" is the current value of the dyntick counter that is incremented
 	or one greater than the interrupt-nesting depth otherwise.
 	The number after the second "/" is the NMI nesting depth.
 
-	This field is displayed only for CONFIG_NO_HZ kernels.
-
 o	"df" is the number of times that some other CPU has forced a
 	quiescent state on behalf of this CPU due to this CPU being in
 	dynticks-idle state.
 
-	This field is displayed only for CONFIG_NO_HZ kernels.
-
 o	"of" is the number of times that some other CPU has forced a
 	quiescent state on behalf of this CPU due to this CPU being
 	offline.  In a perfect world, this might never happen, but it

trunk/Documentation/RCU/whatisRCU.txt

@@ -4,6 +4,7 @@ to start learning about RCU:
 1.	What is RCU, Fundamentally?  http://lwn.net/Articles/262464/
 2.	What is RCU? Part 2: Usage   http://lwn.net/Articles/263130/
 3.	RCU part 3: the RCU API      http://lwn.net/Articles/264090/
+4.	The RCU API, 2010 Edition    http://lwn.net/Articles/418853/
 
 
 What is RCU?
@@ -834,6 +835,8 @@ SRCU:	Critical sections	Grace period		Barrier
 
 	srcu_read_lock		synchronize_srcu	N/A
 	srcu_read_unlock	synchronize_srcu_expedited
+	srcu_read_lock_raw
+	srcu_read_unlock_raw
 	srcu_dereference
 
 SRCU:	Initialization/cleanup
@@ -855,27 +858,33 @@ list can be helpful:
 
 a.	Will readers need to block?  If so, you need SRCU.
 
-b.	What about the -rt patchset?  If readers would need to block
+b.	Is it necessary to start a read-side critical section in a
+	hardirq handler or exception handler, and then to complete
+	this read-side critical section in the task that was
+	interrupted?  If so, you need SRCU's srcu_read_lock_raw() and
+	srcu_read_unlock_raw() primitives.
+
+c.	What about the -rt patchset?  If readers would need to block
 	in an non-rt kernel, you need SRCU.  If readers would block
 	in a -rt kernel, but not in a non-rt kernel, SRCU is not
 	necessary.
 
-c.	Do you need to treat NMI handlers, hardirq handlers,
+d.	Do you need to treat NMI handlers, hardirq handlers,
 	and code segments with preemption disabled (whether
 	via preempt_disable(), local_irq_save(), local_bh_disable(),
 	or some other mechanism) as if they were explicit RCU readers?
 	If so, you need RCU-sched.
 
-d.	Do you need RCU grace periods to complete even in the face
+e.	Do you need RCU grace periods to complete even in the face
 	of softirq monopolization of one or more of the CPUs?  For
 	example, is your code subject to network-based denial-of-service
 	attacks?  If so, you need RCU-bh.
 
-e.	Is your workload too update-intensive for normal use of
+f.	Is your workload too update-intensive for normal use of
 	RCU, but inappropriate for other synchronization mechanisms?
 	If so, consider SLAB_DESTROY_BY_RCU.  But please be careful!
 
-f.	Otherwise, use RCU.
+g.	Otherwise, use RCU.
 
 Of course, this all assumes that you have determined that RCU is in fact
 the right tool for your job.

trunk/Documentation/atomic_ops.txt

@@ -84,6 +84,93 @@ compiler optimizes the section accessing atomic_t variables.
 
 *** YOU HAVE BEEN WARNED! ***
 
+Properly aligned pointers, longs, ints, and chars (and unsigned
+equivalents) may be atomically loaded from and stored to in the same
+sense as described for atomic_read() and atomic_set().  The ACCESS_ONCE()
+macro should be used to prevent the compiler from using optimizations
+that might otherwise optimize accesses out of existence on the one hand,
+or that might create unsolicited accesses on the other.
+
+For example consider the following code:
+
+	while (a > 0)
+		do_something();
+
+If the compiler can prove that do_something() does not store to the
+variable a, then the compiler is within its rights transforming this to
+the following:
+
+	tmp = a;
+	if (a > 0)
+		for (;;)
+			do_something();
+
+If you don't want the compiler to do this (and you probably don't), then
+you should use something like the following:
+
+	while (ACCESS_ONCE(a) < 0)
+		do_something();
+
+Alternatively, you could place a barrier() call in the loop.
+
+For another example, consider the following code:
+
+	tmp_a = a;
+	do_something_with(tmp_a);
+	do_something_else_with(tmp_a);
+
+If the compiler can prove that do_something_with() does not store to the
+variable a, then the compiler is within its rights to manufacture an
+additional load as follows:
+
+	tmp_a = a;
+	do_something_with(tmp_a);
+	tmp_a = a;
+	do_something_else_with(tmp_a);
+
+This could fatally confuse your code if it expected the same value
+to be passed to do_something_with() and do_something_else_with().
+
+The compiler would be likely to manufacture this additional load if
+do_something_with() was an inline function that made very heavy use
+of registers: reloading from variable a could save a flush to the
+stack and later reload.  To prevent the compiler from attacking your
+code in this manner, write the following:
+
+	tmp_a = ACCESS_ONCE(a);
+	do_something_with(tmp_a);
+	do_something_else_with(tmp_a);
+
+For a final example, consider the following code, assuming that the
+variable a is set at boot time before the second CPU is brought online
+and never changed later, so that memory barriers are not needed:
+
+	if (a)
+		b = 9;
+	else
+		b = 42;
+
+The compiler is within its rights to manufacture an additional store
+by transforming the above code into the following:
+
+	b = 42;
+	if (a)
+		b = 9;
+
+This could come as a fatal surprise to other code running concurrently
+that expected b to never have the value 42 if a was zero.  To prevent
+the compiler from doing this, write something like:
+
+	if (a)
+		ACCESS_ONCE(b) = 9;
+	else
+		ACCESS_ONCE(b) = 42;
+
+Don't even -think- about doing this without proper use of memory barriers,
+locks, or atomic operations if variable a can change at runtime!
+
+*** WARNING: ACCESS_ONCE() DOES NOT IMPLY A BARRIER! ***
+
 Now, we move onto the atomic operation interfaces typically implemented with
 the help of assembly code.