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authorArnd Bergmann <arnd@arndb.de>2012-05-14 15:23:13 +0200
committerArnd Bergmann <arnd@arndb.de>2012-05-14 15:23:13 +0200
commit6b204283f2802a92cf91fc14c2c1b04e7295761b (patch)
treee323818ac7f159c13f646fdf75bf0f016d7ae368 /Documentation
parentffc505c0b99d6caf5b10d813f9a0ce3576f68996 (diff)
parenta0f5e3631b07cabf624e7d818df76d47d9d21017 (diff)
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Merge branch 'imx/pinctrl' into imx/dt
Conflicts: drivers/mmc/host/sdhci-esdhc-imx.c drivers/net/ethernet/freescale/fec.c drivers/spi/spi-imx.c drivers/tty/serial/imx.c This resolves some simply but annoying conflicts. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-hsi19
-rw-r--r--Documentation/power/freezing-of-tasks.txt37
-rw-r--r--Documentation/security/keys.txt14
3 files changed, 51 insertions, 19 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-hsi b/Documentation/ABI/testing/sysfs-bus-hsi
new file mode 100644
index 000000000000..1b1b282a99e1
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-hsi
@@ -0,0 +1,19 @@
+What: /sys/bus/hsi
+Date: April 2012
+KernelVersion: 3.4
+Contact: Carlos Chinea <carlos.chinea@nokia.com>
+Description:
+ High Speed Synchronous Serial Interface (HSI) is a
+ serial interface mainly used for connecting application
+ engines (APE) with cellular modem engines (CMT) in cellular
+ handsets.
+ The bus will be populated with devices (hsi_clients) representing
+ the protocols available in the system. Bus drivers implement
+ those protocols.
+
+What: /sys/bus/hsi/devices/.../modalias
+Date: April 2012
+KernelVersion: 3.4
+Contact: Carlos Chinea <carlos.chinea@nokia.com>
+Description: Stores the same MODALIAS value emitted by uevent
+ Format: hsi:<hsi_client device name>
diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt
index ec715cd78fbb..6ec291ea1c78 100644
--- a/Documentation/power/freezing-of-tasks.txt
+++ b/Documentation/power/freezing-of-tasks.txt
@@ -9,7 +9,7 @@ architectures).
II. How does it work?
-There are four per-task flags used for that, PF_NOFREEZE, PF_FROZEN, TIF_FREEZE
+There are three per-task flags used for that, PF_NOFREEZE, PF_FROZEN
and PF_FREEZER_SKIP (the last one is auxiliary). The tasks that have
PF_NOFREEZE unset (all user space processes and some kernel threads) are
regarded as 'freezable' and treated in a special way before the system enters a
@@ -17,30 +17,31 @@ suspend state as well as before a hibernation image is created (in what follows
we only consider hibernation, but the description also applies to suspend).
Namely, as the first step of the hibernation procedure the function
-freeze_processes() (defined in kernel/power/process.c) is called. It executes
-try_to_freeze_tasks() that sets TIF_FREEZE for all of the freezable tasks and
-either wakes them up, if they are kernel threads, or sends fake signals to them,
-if they are user space processes. A task that has TIF_FREEZE set, should react
-to it by calling the function called __refrigerator() (defined in
-kernel/freezer.c), which sets the task's PF_FROZEN flag, changes its state
-to TASK_UNINTERRUPTIBLE and makes it loop until PF_FROZEN is cleared for it.
-Then, we say that the task is 'frozen' and therefore the set of functions
-handling this mechanism is referred to as 'the freezer' (these functions are
-defined in kernel/power/process.c, kernel/freezer.c & include/linux/freezer.h).
-User space processes are generally frozen before kernel threads.
+freeze_processes() (defined in kernel/power/process.c) is called. A system-wide
+variable system_freezing_cnt (as opposed to a per-task flag) is used to indicate
+whether the system is to undergo a freezing operation. And freeze_processes()
+sets this variable. After this, it executes try_to_freeze_tasks() that sends a
+fake signal to all user space processes, and wakes up all the kernel threads.
+All freezable tasks must react to that by calling try_to_freeze(), which
+results in a call to __refrigerator() (defined in kernel/freezer.c), which sets
+the task's PF_FROZEN flag, changes its state to TASK_UNINTERRUPTIBLE and makes
+it loop until PF_FROZEN is cleared for it. Then, we say that the task is
+'frozen' and therefore the set of functions handling this mechanism is referred
+to as 'the freezer' (these functions are defined in kernel/power/process.c,
+kernel/freezer.c & include/linux/freezer.h). User space processes are generally
+frozen before kernel threads.
__refrigerator() must not be called directly. Instead, use the
try_to_freeze() function (defined in include/linux/freezer.h), that checks
-the task's TIF_FREEZE flag and makes the task enter __refrigerator() if the
-flag is set.
+if the task is to be frozen and makes the task enter __refrigerator().
For user space processes try_to_freeze() is called automatically from the
signal-handling code, but the freezable kernel threads need to call it
explicitly in suitable places or use the wait_event_freezable() or
wait_event_freezable_timeout() macros (defined in include/linux/freezer.h)
-that combine interruptible sleep with checking if TIF_FREEZE is set and calling
-try_to_freeze(). The main loop of a freezable kernel thread may look like the
-following one:
+that combine interruptible sleep with checking if the task is to be frozen and
+calling try_to_freeze(). The main loop of a freezable kernel thread may look
+like the following one:
set_freezable();
do {
@@ -53,7 +54,7 @@ following one:
(from drivers/usb/core/hub.c::hub_thread()).
If a freezable kernel thread fails to call try_to_freeze() after the freezer has
-set TIF_FREEZE for it, the freezing of tasks will fail and the entire
+initiated a freezing operation, the freezing of tasks will fail and the entire
hibernation operation will be cancelled. For this reason, freezable kernel
threads must call try_to_freeze() somewhere or use one of the
wait_event_freezable() and wait_event_freezable_timeout() macros.
diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt
index 787717091421..d389acd31e19 100644
--- a/Documentation/security/keys.txt
+++ b/Documentation/security/keys.txt
@@ -123,7 +123,7 @@ KEY SERVICE OVERVIEW
The key service provides a number of features besides keys:
- (*) The key service defines two special key types:
+ (*) The key service defines three special key types:
(+) "keyring"
@@ -137,6 +137,18 @@ The key service provides a number of features besides keys:
blobs of data. These can be created, updated and read by userspace,
and aren't intended for use by kernel services.
+ (+) "logon"
+
+ Like a "user" key, a "logon" key has a payload that is an arbitrary
+ blob of data. It is intended as a place to store secrets which are
+ accessible to the kernel but not to userspace programs.
+
+ The description can be arbitrary, but must be prefixed with a non-zero
+ length string that describes the key "subclass". The subclass is
+ separated from the rest of the description by a ':'. "logon" keys can
+ be created and updated from userspace, but the payload is only
+ readable from kernel space.
+
(*) Each process subscribes to three keyrings: a thread-specific keyring, a
process-specific keyring, and a session-specific keyring.