---

yaml
---
r: 94838
b: refs/heads/master
c: 1f43c53
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e90955c26d8af318658c45caadb1d330ac6a506c
+refs/heads/master: 1f43c5393033de90bac4410352b1d2a69dcbe7ef

trunk/Documentation/DMA-API.txt

@@ -145,7 +145,7 @@ Part Ic - DMA addressing limitations
 int
 dma_supported(struct device *dev, u64 mask)
 int
-pci_dma_supported(struct device *dev, u64 mask)
+pci_dma_supported(struct pci_dev *hwdev, u64 mask)
 
 Checks to see if the device can support DMA to the memory described by
 mask.
@@ -189,7 +189,7 @@ dma_addr_t
 dma_map_single(struct device *dev, void *cpu_addr, size_t size,
 		      enum dma_data_direction direction)
 dma_addr_t
-pci_map_single(struct device *dev, void *cpu_addr, size_t size,
+pci_map_single(struct pci_dev *hwdev, void *cpu_addr, size_t size,
 		      int direction)
 
 Maps a piece of processor virtual memory so it can be accessed by the
@@ -395,6 +395,71 @@ Notes:  You must do this:
 
 See also dma_map_single().
 
+dma_addr_t
+dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
+		     enum dma_data_direction dir,
+		     struct dma_attrs *attrs)
+
+void
+dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
+		       size_t size, enum dma_data_direction dir,
+		       struct dma_attrs *attrs)
+
+int
+dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+		 int nents, enum dma_data_direction dir,
+		 struct dma_attrs *attrs)
+
+void
+dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
+		   int nents, enum dma_data_direction dir,
+		   struct dma_attrs *attrs)
+
+The four functions above are just like the counterpart functions
+without the _attrs suffixes, except that they pass an optional
+struct dma_attrs*.
+
+struct dma_attrs encapsulates a set of "dma attributes". For the
+definition of struct dma_attrs see linux/dma-attrs.h.
+
+The interpretation of dma attributes is architecture-specific, and
+each attribute should be documented in Documentation/DMA-attributes.txt.
+
+If struct dma_attrs* is NULL, the semantics of each of these
+functions is identical to those of the corresponding function
+without the _attrs suffix. As a result dma_map_single_attrs()
+can generally replace dma_map_single(), etc.
+
+As an example of the use of the *_attrs functions, here's how
+you could pass an attribute DMA_ATTR_FOO when mapping memory
+for DMA:
+
+#include <linux/dma-attrs.h>
+/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and
+ * documented in Documentation/DMA-attributes.txt */
+...
+
+	DEFINE_DMA_ATTRS(attrs);
+	dma_set_attr(DMA_ATTR_FOO, &attrs);
+	....
+	n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr);
+	....
+
+Architectures that care about DMA_ATTR_FOO would check for its
+presence in their implementations of the mapping and unmapping
+routines, e.g.:
+
+void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
+			     size_t size, enum dma_data_direction dir,
+			     struct dma_attrs *attrs)
+{
+	....
+	int foo =  dma_get_attr(DMA_ATTR_FOO, attrs);
+	....
+	if (foo)
+		/* twizzle the frobnozzle */
+	....
+
 
 Part II - Advanced dma_ usage
 -----------------------------

trunk/Documentation/DMA-attributes.txt

@@ -0,0 +1,24 @@
+			DMA attributes
+			==============
+
+This document describes the semantics of the DMA attributes that are
+defined in linux/dma-attrs.h.
+
+DMA_ATTR_WRITE_BARRIER
+----------------------
+
+DMA_ATTR_WRITE_BARRIER is a (write) barrier attribute for DMA.  DMA
+to a memory region with the DMA_ATTR_WRITE_BARRIER attribute forces
+all pending DMA writes to complete, and thus provides a mechanism to
+strictly order DMA from a device across all intervening busses and
+bridges.  This barrier is not specific to a particular type of
+interconnect, it applies to the system as a whole, and so its
+implementation must account for the idiosyncracies of the system all
+the way from the DMA device to memory.
+
+As an example of a situation where DMA_ATTR_WRITE_BARRIER would be
+useful, suppose that a device does a DMA write to indicate that data is
+ready and available in memory.  The DMA of the "completion indication"
+could race with data DMA.  Mapping the memory used for completion
+indications with DMA_ATTR_WRITE_BARRIER would prevent the race.
+

trunk/Documentation/cgroups.txt

@@ -500,8 +500,7 @@ post-attachment activity that requires memory allocations or blocking.
 
 void fork(struct cgroup_subsy *ss, struct task_struct *task)
 
-Called when a task is forked into a cgroup. Also called during
-registration for all existing tasks.
+Called when a task is forked into a cgroup.
 
 void exit(struct cgroup_subsys *ss, struct task_struct *task)
 

trunk/Documentation/controllers/devices.txt

@@ -0,0 +1,48 @@
+Device Whitelist Controller
+
+1. Description:
+
+Implement a cgroup to track and enforce open and mknod restrictions
+on device files.  A device cgroup associates a device access
+whitelist with each cgroup.  A whitelist entry has 4 fields.
+'type' is a (all), c (char), or b (block).  'all' means it applies
+to all types and all major and minor numbers.  Major and minor are
+either an integer or * for all.  Access is a composition of r
+(read), w (write), and m (mknod).
+
+The root device cgroup starts with rwm to 'all'.  A child device
+cgroup gets a copy of the parent.  Administrators can then remove
+devices from the whitelist or add new entries.  A child cgroup can
+never receive a device access which is denied its parent.  However
+when a device access is removed from a parent it will not also be
+removed from the child(ren).
+
+2. User Interface
+
+An entry is added using devices.allow, and removed using
+devices.deny.  For instance
+
+	echo 'c 1:3 mr' > /cgroups/1/devices.allow
+
+allows cgroup 1 to read and mknod the device usually known as
+/dev/null.  Doing
+
+	echo a > /cgroups/1/devices.deny
+
+will remove the default 'a *:* mrw' entry.
+
+3. Security
+
+Any task can move itself between cgroups.  This clearly won't
+suffice, but we can decide the best way to adequately restrict
+movement as people get some experience with this.  We may just want
+to require CAP_SYS_ADMIN, which at least is a separate bit from
+CAP_MKNOD.  We may want to just refuse moving to a cgroup which
+isn't a descendent of the current one.  Or we may want to use
+CAP_MAC_ADMIN, since we really are trying to lock down root.
+
+CAP_SYS_ADMIN is needed to modify the whitelist or move another
+task to a new cgroup.  (Again we'll probably want to change that).
+
+A cgroup may not be granted more permissions than the cgroup's
+parent has.

trunk/Documentation/controllers/resource_counter.txt

@@ -0,0 +1,181 @@
+
+		The Resource Counter
+
+The resource counter, declared at include/linux/res_counter.h,
+is supposed to facilitate the resource management by controllers
+by providing common stuff for accounting.
+
+This "stuff" includes the res_counter structure and routines
+to work with it.
+
+
+
+1. Crucial parts of the res_counter structure
+
+ a. unsigned long long usage
+
+ 	The usage value shows the amount of a resource that is consumed
+	by a group at a given time. The units of measurement should be
+	determined by the controller that uses this counter. E.g. it can
+	be bytes, items or any other unit the controller operates on.
+
+ b. unsigned long long max_usage
+
+ 	The maximal value of the usage over time.
+
+ 	This value is useful when gathering statistical information about
+	the particular group, as it shows the actual resource requirements
+	for a particular group, not just some usage snapshot.
+
+ c. unsigned long long limit
+
+ 	The maximal allowed amount of resource to consume by the group. In
+	case the group requests for more resources, so that the usage value
+	would exceed the limit, the resource allocation is rejected (see
+	the next section).
+
+ d. unsigned long long failcnt
+
+ 	The failcnt stands for "failures counter". This is the number of
+	resource allocation attempts that failed.
+
+ c. spinlock_t lock
+
+ 	Protects changes of the above values.
+
+
+
+2. Basic accounting routines
+
+ a. void res_counter_init(struct res_counter *rc)
+
+ 	Initializes the resource counter. As usual, should be the first
+	routine called for a new counter.
+
+ b. int res_counter_charge[_locked]
+			(struct res_counter *rc, unsigned long val)
+
+	When a resource is about to be allocated it has to be accounted
+	with the appropriate resource counter (controller should determine
+	which one to use on its own). This operation is called "charging".
+
+	This is not very important which operation - resource allocation
+	or charging - is performed first, but
+	  * if the allocation is performed first, this may create a
+	    temporary resource over-usage by the time resource counter is
+	    charged;
+	  * if the charging is performed first, then it should be uncharged
+	    on error path (if the one is called).
+
+ c. void res_counter_uncharge[_locked]
+			(struct res_counter *rc, unsigned long val)
+
+	When a resource is released (freed) it should be de-accounted
+	from the resource counter it was accounted to.  This is called
+	"uncharging".
+
+    The _locked routines imply that the res_counter->lock is taken.
+
+
+ 2.1 Other accounting routines
+
+    There are more routines that may help you with common needs, like
+    checking whether the limit is reached or resetting the max_usage
+    value. They are all declared in include/linux/res_counter.h.
+
+
+
+3. Analyzing the resource counter registrations
+
+ a. If the failcnt value constantly grows, this means that the counter's
+    limit is too tight. Either the group is misbehaving and consumes too
+    many resources, or the configuration is not suitable for the group
+    and the limit should be increased.
+
+ b. The max_usage value can be used to quickly tune the group. One may
+    set the limits to maximal values and either load the container with
+    a common pattern or leave one for a while. After this the max_usage
+    value shows the amount of memory the container would require during
+    its common activity.
+
+    Setting the limit a bit above this value gives a pretty good
+    configuration that works in most of the cases.
+
+ c. If the max_usage is much less than the limit, but the failcnt value
+    is growing, then the group tries to allocate a big chunk of resource
+    at once.
+
+ d. If the max_usage is much less than the limit, but the failcnt value
+    is 0, then this group is given too high limit, that it does not
+    require. It is better to lower the limit a bit leaving more resource
+    for other groups.
+
+
+
+4. Communication with the control groups subsystem (cgroups)
+
+All the resource controllers that are using cgroups and resource counters
+should provide files (in the cgroup filesystem) to work with the resource
+counter fields. They are recommended to adhere to the following rules:
+
+ a. File names
+
+ 	Field name	File name
+	---------------------------------------------------
+	usage		usage_in_<unit_of_measurement>
+	max_usage	max_usage_in_<unit_of_measurement>
+	limit		limit_in_<unit_of_measurement>
+	failcnt		failcnt
+	lock		no file :)
+
+ b. Reading from file should show the corresponding field value in the
+    appropriate format.
+
+ c. Writing to file
+
+ 	Field		Expected behavior
+	----------------------------------
+	usage		prohibited
+	max_usage	reset to usage
+	limit		set the limit
+	failcnt		reset to zero
+
+
+
+5. Usage example
+
+ a. Declare a task group (take a look at cgroups subsystem for this) and
+    fold a res_counter into it
+
+	struct my_group {
+		struct res_counter res;
+
+		<other fields>
+	}
+
+ b. Put hooks in resource allocation/release paths
+
+ 	int alloc_something(...)
+	{
+		if (res_counter_charge(res_counter_ptr, amount) < 0)
+			return -ENOMEM;
+
+		<allocate the resource and return to the caller>
+	}
+
+	void release_something(...)
+	{
+		res_counter_uncharge(res_counter_ptr, amount);
+
+		<release the resource>
+	}
+
+    In order to keep the usage value self-consistent, both the
+    "res_counter_ptr" and the "amount" in release_something() should be
+    the same as they were in the alloc_something() when the releasing
+    resource was allocated.
+
+ c. Provide the way to read res_counter values and set them (the cgroups
+    still can help with it).
+
+ c. Compile and run :)

trunk/Documentation/cpu-freq/user-guide.txt

@@ -154,6 +154,11 @@ scaling_governor,		and by "echoing" the name of another
 				that some governors won't load - they only
 				work on some specific architectures or
 				processors.
+
+cpuinfo_cur_freq :		Current speed of the CPU, in KHz.
+
+scaling_available_frequencies : List of available frequencies, in KHz.
+
 scaling_min_freq and
 scaling_max_freq		show the current "policy limits" (in
 				kHz). By echoing new values into these
@@ -162,6 +167,15 @@ scaling_max_freq		show the current "policy limits" (in
 				first set scaling_max_freq, then
 				scaling_min_freq.
 
+affected_cpus :			List of CPUs that require software coordination
+				of frequency.
+
+related_cpus :			List of CPUs that need some sort of frequency
+				coordination, whether software or hardware.
+
+scaling_driver :		Hardware driver for cpufreq.
+
+scaling_cur_freq :		Current frequency of the CPU, in KHz.
 
 If you have selected the "userspace" governor which allows you to
 set the CPU operating frequency to a specific value, you can read out