From 24b7099af71232b7568acd74770e6eb8f174f5d6 Mon Sep 17 00:00:00 2001 From: Carlos Chinea Date: Fri, 13 Apr 2012 15:55:13 +0300 Subject: HSI: Add HSI ABI documentation Adds sysfs HSI framework documentation Signed-off-by: Carlos Chinea Acked-by: Greg Kroah-Hartman Acked-by: Linus Walleij --- Documentation/ABI/testing/sysfs-bus-hsi | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-hsi (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-bus-hsi b/Documentation/ABI/testing/sysfs-bus-hsi new file mode 100644 index 0000000..1b1b282 --- /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 +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 +Description: Stores the same MODALIAS value emitted by uevent + Format: hsi: -- cgit v1.1 From a05a4830a32ef9f89e7bd372a7bae9b96b1ac266 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 25 Apr 2012 12:46:50 -0400 Subject: keys: update the documentation with info about "logon" keys Acked-by: David Howells Signed-off-by: Jeff Layton --- Documentation/security/keys.txt | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt index 7877170..d389acd 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. -- cgit v1.1 From 26e0f90fded422f309deb6169dfbccb204435698 Mon Sep 17 00:00:00 2001 From: Marcos Paulo de Souza Date: Sun, 29 Apr 2012 22:29:30 +0200 Subject: PM / Freezer / Docs: Update documentation about freezing of tasks The file Documentation/power/freezing-of-tasks.txt was still referencing the TIF_FREEZE flag, that was removed by the commit d88e4cb67197d007fb778d62fe17360e970d5bfa(freezer: remove now unused TIF_FREEZE). This patch removes all the references of TIF_FREEZE that were left behind. Signed-off-by: Marcos Paulo de Souza Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- Documentation/power/freezing-of-tasks.txt | 37 ++++++++++++++++--------------- 1 file changed, 19 insertions(+), 18 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt index ec715cd..6ec291e 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. -- cgit v1.1