path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 18:10:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 18:10:18 -0700
commit08615d7d85e5aa02c05bf6c4dde87d940e7f85f6 (patch)
tree18906149d313d25914160aca21cedf54b3a7e818 /Documentation
parentMerge branch 'drm-prime-vmap' of git://people.freedesktop.org/~airlied/linux (diff)
parentkconfig: update compression algorithm info (diff)
Merge branch 'akpm' (Andrew's patch-bomb)
Merge misc patches from Andrew Morton: - the "misc" tree - stuff from all over the map - checkpatch updates - fatfs - kmod changes - procfs - cpumask - UML - kexec - mqueue - rapidio - pidns - some checkpoint-restore feature work. Reluctantly. Most of it delayed a release. I'm still rather worried that we don't have a clear roadmap to completion for this work. * emailed from Andrew Morton <akpm@linux-foundation.org>: (78 patches) kconfig: update compression algorithm info c/r: prctl: add ability to set new mm_struct::exe_file c/r: prctl: extend PR_SET_MM to set up more mm_struct entries c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat syscalls, x86: add __NR_kcmp syscall fs, proc: introduce /proc/<pid>/task/<tid>/children entry sysctl: make kernel.ns_last_pid control dependent on CHECKPOINT_RESTORE aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() eventfd: change int to __u64 in eventfd_signal() fs/nls: add Apple NLS pidns: make killed children autoreap pidns: use task_active_pid_ns in do_notify_parent rapidio/tsi721: add DMA engine support rapidio: add DMA engine support for RIO data transfers ipc/mqueue: add rbtree node caching support tools/selftests: add mq_perf_tests ipc/mqueue: strengthen checks on mqueue creation ipc/mqueue: correct mq_attr_ok test ipc/mqueue: improve performance of send/recv selftests: add mq_open_tests ...
Diffstat (limited to 'Documentation')
4 files changed, 45 insertions, 3 deletions
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index c58b236bbe04..cb9258b8fd35 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -671,8 +671,9 @@ ones already enabled by DEBUG.
Chapter 14: Allocating memory
The kernel provides the following general purpose memory allocators:
-kmalloc(), kzalloc(), kcalloc(), vmalloc(), and vzalloc(). Please refer to
-the API documentation for further information about them.
+kmalloc(), kzalloc(), kmalloc_array(), kcalloc(), vmalloc(), and
+vzalloc(). Please refer to the API documentation for further information
+about them.
The preferred form for passing a size of a struct is the following:
@@ -686,6 +687,17 @@ Casting the return value which is a void pointer is redundant. The conversion
from void pointer to any other pointer type is guaranteed by the C programming
+The preferred form for allocating an array is the following:
+ p = kmalloc_array(n, sizeof(...), ...);
+The preferred form for allocating a zeroed array is the following:
+ p = kcalloc(n, sizeof(...), ...);
+Both forms check for overflow on the allocation size n * sizeof(...),
+and return NULL if that occurred.
Chapter 15: The inline disease
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 912af6ce5626..fb0a6aeb936c 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -40,6 +40,7 @@ Table of Contents
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
3.5 /proc/<pid>/mountinfo - Information about mounts
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
+ 3.7 /proc/<pid>/task/<tid>/children - Information about task children
4 Configuring procfs
4.1 Mount options
@@ -310,6 +311,11 @@ Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
start_data address above which program data+bss is placed
end_data address below which program data+bss is placed
start_brk address above which program heap can be expanded with brk()
+ arg_start address above which program command line is placed
+ arg_end address below which program command line is placed
+ env_start address above which program environment is placed
+ env_end address below which program environment is placed
+ exit_code the thread's exit_code in the form reported by the waitpid system call
The /proc/PID/maps file containing the currently mapped memory regions and
@@ -1578,6 +1584,23 @@ then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
comm value.
+3.7 /proc/<pid>/task/<tid>/children - Information about task children
+This file provides a fast way to retrieve first level children pids
+of a task pointed by <pid>/<tid> pair. The format is a space separated
+stream of pids.
+Note the "first level" here -- if a child has own children they will
+not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children
+to obtain the descendants.
+Since this interface is intended to be fast and cheap it doesn't
+guarantee to provide precise results and some children might be
+skipped, especially if they've exited right after we printed their
+pids, so one need to either stop or freeze processes being inspected
+if precise results are needed.
Configuring procfs
diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index 88fd7f5c8dcd..13d6166d7a27 100644
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -225,6 +225,13 @@ a queue must be less or equal then msg_max.
maximum message size value (it is every message queue's attribute set during
its creation).
+/proc/sys/fs/mqueue/msg_default is a read/write file for setting/getting the
+default number of messages in a queue value if attr parameter of mq_open(2) is
+NULL. If it exceed msg_max, the default value is initialized msg_max.
+/proc/sys/fs/mqueue/msgsize_default is a read/write file for setting/getting
+the default message size value if attr parameter of mq_open(2) is NULL. If it
+exceed msgsize_max, the default value is initialized msgsize_max.
4. /proc/sys/fs/epoll - Configuration options for the epoll interface
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index 4600cbe3d6be..7587493c67f1 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -16,7 +16,7 @@ There are three components to pagemap:
* Bits 0-4 swap type if swapped
* Bits 5-54 swap offset if swapped
* Bits 55-60 page shift (page size = 1<<page shift)
- * Bit 61 reserved for future use
+ * Bit 61 page is file-page or shared-anon
* Bit 62 page swapped
* Bit 63 page present