---

yaml
---
r: 161356
b: refs/heads/master
c: f86054c
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 33f82d141c897f39cd8bce592d88cb3c5af58342
+refs/heads/master: f86054c24565d09d1997f03192761dabf6b8a9c9

trunk/Documentation/arm/Samsung-S3C24XX/CPUfreq.txt

@@ -0,0 +1,75 @@
+		S3C24XX CPUfreq support
+		=======================
+
+Introduction
+------------
+
+ The S3C24XX series support a number of power saving systems, such as
+ the ability to change the core, memory and peripheral operating
+ frequencies. The core control is exported via the CPUFreq driver
+ which has a number of different manual or automatic controls over the
+ rate the core is running at.
+
+ There are two forms of the driver depending on the specific CPU and
+ how the clocks are arranged. The first implementation used as single
+ PLL to feed the ARM, memory and peripherals via a series of dividers
+ and muxes and this is the implementation that is documented here. A
+ newer version where there is a seperate PLL and clock divider for the
+ ARM core is available as a seperate driver.
+
+
+Layout
+------
+
+ The code core manages the CPU specific drivers, any data that they
+ need to register and the interface to the generic drivers/cpufreq
+ system. Each CPU registers a driver to control the PLL, clock dividers
+ and anything else associated with it. Any board that wants to use this
+ framework needs to supply at least basic details of what is required.
+
+ The core registers with drivers/cpufreq at init time if all the data
+ necessary has been supplied.
+
+
+CPU support
+-----------
+
+ The support for each CPU depends on the facilities provided by the
+ SoC and the driver as each device has different PLL and clock chains
+ associated with it.
+
+
+Slow Mode
+---------
+
+ The SLOW mode where the PLL is turned off altogether and the
+ system is fed by the external crystal input is currently not
+ supported.
+
+
+sysfs
+-----
+
+ The core code exports extra information via sysfs in the directory
+ devices/system/cpu/cpu0/arch-freq.
+
+
+Board Support
+-------------
+
+ Each board that wants to use the cpufreq code must register some basic
+ information with the core driver to provide information about what the
+ board requires and any restrictions being placed on it.
+
+ The board needs to supply information about whether it needs the IO bank
+ timings changing, any maximum frequency limits and information about the
+ SDRAM refresh rate.
+
+
+
+
+Document Author
+---------------
+
+Ben Dooks, Copyright 2009 Simtec Electronics
+Licensed under GPLv2

trunk/Documentation/filesystems/gfs2-uevents.txt

@@ -0,0 +1,100 @@
+                              uevents and GFS2
+                             ==================
+
+During the lifetime of a GFS2 mount, a number of uevents are generated.
+This document explains what the events are and what they are used
+for (by gfs_controld in gfs2-utils).
+
+A list of GFS2 uevents
+-----------------------
+
+1. ADD
+
+The ADD event occurs at mount time. It will always be the first
+uevent generated by the newly created filesystem. If the mount
+is successful, an ONLINE uevent will follow.  If it is not successful
+then a REMOVE uevent will follow.
+
+The ADD uevent has two environment variables: SPECTATOR=[0|1]
+and RDONLY=[0|1] that specify the spectator status (a read-only mount
+with no journal assigned), and read-only (with journal assigned) status
+of the filesystem respectively.
+
+2. ONLINE
+
+The ONLINE uevent is generated after a successful mount or remount. It
+has the same environment variables as the ADD uevent. The ONLINE
+uevent, along with the two environment variables for spectator and
+RDONLY are a relatively recent addition (2.6.32-rc+) and will not
+be generated by older kernels.
+
+3. CHANGE
+
+The CHANGE uevent is used in two places. One is when reporting the
+successful mount of the filesystem by the first node (FIRSTMOUNT=Done).
+This is used as a signal by gfs_controld that it is then ok for other
+nodes in the cluster to mount the filesystem.
+
+The other CHANGE uevent is used to inform of the completion
+of journal recovery for one of the filesystems journals. It has
+two environment variables, JID= which specifies the journal id which
+has just been recovered, and RECOVERY=[Done|Failed] to indicate the
+success (or otherwise) of the operation. These uevents are generated
+for every journal recovered, whether it is during the initial mount
+process or as the result of gfs_controld requesting a specific journal
+recovery via the /sys/fs/gfs2/<fsname>/lock_module/recovery file.
+
+Because the CHANGE uevent was used (in early versions of gfs_controld)
+without checking the environment variables to discover the state, we
+cannot add any more functions to it without running the risk of
+someone using an older version of the user tools and breaking their
+cluster. For this reason the ONLINE uevent was used when adding a new
+uevent for a successful mount or remount.
+
+4. OFFLINE
+
+The OFFLINE uevent is only generated due to filesystem errors and is used
+as part of the "withdraw" mechanism. Currently this doesn't give any
+information about what the error is, which is something that needs to
+be fixed.
+
+5. REMOVE
+
+The REMOVE uevent is generated at the end of an unsuccessful mount
+or at the end of a umount of the filesystem. All REMOVE uevents will
+have been preceeded by at least an ADD uevent for the same fileystem,
+and unlike the other uevents is generated automatically by the kernel's
+kobject subsystem.
+
+
+Information common to all GFS2 uevents (uevent environment variables)
+----------------------------------------------------------------------
+
+1. LOCKTABLE=
+
+The LOCKTABLE is a string, as supplied on the mount command
+line (locktable=) or via fstab. It is used as a filesystem label
+as well as providing the information for a lock_dlm mount to be
+able to join the cluster.
+
+2. LOCKPROTO=
+
+The LOCKPROTO is a string, and its value depends on what is set
+on the mount command line, or via fstab. It will be either
+lock_nolock or lock_dlm. In the future other lock managers
+may be supported.
+
+3. JOURNALID=
+
+If a journal is in use by the filesystem (journals are not
+assigned for spectator mounts) then this will give the
+numeric journal id in all GFS2 uevents.
+
+4. UUID=
+
+With recent versions of gfs2-utils, mkfs.gfs2 writes a UUID
+into the filesystem superblock. If it exists, this will
+be included in every uevent relating to the filesystem.
+
+
+

trunk/Documentation/filesystems/seq_file.txt

@@ -46,7 +46,7 @@ better to do. The file is seekable, in that one can do something like the
 following:
 
     dd if=/proc/sequence of=out1 count=1
-    dd if=/proc/sequence skip=1 out=out2 count=1
+    dd if=/proc/sequence skip=1 of=out2 count=1
 
 Then concatenate the output files out1 and out2 and get the right
 result. Yes, it is a thoroughly useless module, but the point is to show

trunk/Documentation/flexible-arrays.txt

@@ -0,0 +1,99 @@
+Using flexible arrays in the kernel
+Last updated for 2.6.31
+Jonathan Corbet <corbet@lwn.net>
+
+Large contiguous memory allocations can be unreliable in the Linux kernel.
+Kernel programmers will sometimes respond to this problem by allocating
+pages with vmalloc().  This solution not ideal, though.  On 32-bit systems,
+memory from vmalloc() must be mapped into a relatively small address space;
+it's easy to run out.  On SMP systems, the page table changes required by
+vmalloc() allocations can require expensive cross-processor interrupts on
+all CPUs.  And, on all systems, use of space in the vmalloc() range
+increases pressure on the translation lookaside buffer (TLB), reducing the
+performance of the system.
+
+In many cases, the need for memory from vmalloc() can be eliminated by
+piecing together an array from smaller parts; the flexible array library
+exists to make this task easier.
+
+A flexible array holds an arbitrary (within limits) number of fixed-sized
+objects, accessed via an integer index.  Sparse arrays are handled
+reasonably well.  Only single-page allocations are made, so memory
+allocation failures should be relatively rare.  The down sides are that the
+arrays cannot be indexed directly, individual object size cannot exceed the
+system page size, and putting data into a flexible array requires a copy
+operation.  It's also worth noting that flexible arrays do no internal
+locking at all; if concurrent access to an array is possible, then the
+caller must arrange for appropriate mutual exclusion.
+
+The creation of a flexible array is done with:
+
+    #include <linux/flex_array.h>
+
+    struct flex_array *flex_array_alloc(int element_size,
+					unsigned int total,
+					gfp_t flags);
+
+The individual object size is provided by element_size, while total is the
+maximum number of objects which can be stored in the array.  The flags
+argument is passed directly to the internal memory allocation calls.  With
+the current code, using flags to ask for high memory is likely to lead to
+notably unpleasant side effects.
+
+Storing data into a flexible array is accomplished with a call to:
+
+    int flex_array_put(struct flex_array *array, unsigned int element_nr,
+    		       void *src, gfp_t flags);
+
+This call will copy the data from src into the array, in the position
+indicated by element_nr (which must be less than the maximum specified when
+the array was created).  If any memory allocations must be performed, flags
+will be used.  The return value is zero on success, a negative error code
+otherwise.
+
+There might possibly be a need to store data into a flexible array while
+running in some sort of atomic context; in this situation, sleeping in the
+memory allocator would be a bad thing.  That can be avoided by using
+GFP_ATOMIC for the flags value, but, often, there is a better way.  The
+trick is to ensure that any needed memory allocations are done before
+entering atomic context, using:
+
+    int flex_array_prealloc(struct flex_array *array, unsigned int start,
+			    unsigned int end, gfp_t flags);
+
+This function will ensure that memory for the elements indexed in the range
+defined by start and end has been allocated.  Thereafter, a
+flex_array_put() call on an element in that range is guaranteed not to
+block.
+
+Getting data back out of the array is done with:
+
+    void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
+
+The return value is a pointer to the data element, or NULL if that
+particular element has never been allocated.
+
+Note that it is possible to get back a valid pointer for an element which
+has never been stored in the array.  Memory for array elements is allocated
+one page at a time; a single allocation could provide memory for several
+adjacent elements.  The flexible array code does not know if a specific
+element has been written; it only knows if the associated memory is
+present.  So a flex_array_get() call on an element which was never stored
+in the array has the potential to return a pointer to random data.  If the
+caller does not have a separate way to know which elements were actually
+stored, it might be wise, at least, to add GFP_ZERO to the flags argument
+to ensure that all elements are zeroed.
+
+There is no way to remove a single element from the array.  It is possible,
+though, to remove all elements with a call to:
+
+    void flex_array_free_parts(struct flex_array *array);
+
+This call frees all elements, but leaves the array itself in place.
+Freeing the entire array is done with:
+
+    void flex_array_free(struct flex_array *array);
+
+As of this writing, there are no users of flexible arrays in the mainline
+kernel.  The functions described here are also not exported to modules;
+that will probably be fixed when somebody comes up with a need for it.