From 818411616baf46ceba0cff6f05af3a9b294734f7 Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Thu, 31 May 2012 16:26:43 -0700 Subject: fs, proc: introduce /proc//task//children entry When we do checkpoint of a task we need to know the list of children the task, has but there is no easy and fast way to generate reverse parent->children chain from arbitrary (while a parent pid is provided in "PPid" field of /proc//status). So instead of walking over all pids in the system (creating one big process tree in memory, just to figure out which children a task has) -- we add explicit /proc//task//children entry, because the kernel already has this kind of information but it is not yet exported. This is a first level children, not the whole process tree. Signed-off-by: Cyrill Gorcunov Reviewed-by: Oleg Nesterov Reviewed-by: Kees Cook Cc: Pavel Emelyanov Cc: Serge Hallyn Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 912af6ce5626..d8d3f9a8e5a3 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -40,6 +40,7 @@ Table of Contents 3.4 /proc//coredump_filter - Core dump filtering settings 3.5 /proc//mountinfo - Information about mounts 3.6 /proc//comm & /proc//task//comm + 3.7 /proc//task//children - Information about task children 4 Configuring procfs 4.1 Mount options @@ -1578,6 +1579,23 @@ then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated comm value. +3.7 /proc//task//children - Information about task children +------------------------------------------------------------------------- +This file provides a fast way to retrieve first level children pids +of a task pointed by / 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//task//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 ------------------------------------------------------------------------------ -- cgit v1.2.3 From 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Thu, 31 May 2012 16:26:44 -0700 Subject: c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat We would like to have an ability to restore command line arguments and program environment pointers but first we need to obtain them somehow. Thus we put these values into /proc/$pid/stat. The exit_code is needed to restore zombie tasks. Signed-off-by: Cyrill Gorcunov Acked-by: Kees Cook Cc: Pavel Emelyanov Cc: Serge Hallyn Cc: KAMEZAWA Hiroyuki Cc: Alexey Dobriyan Cc: Tejun Heo Cc: Andrew Vagin Cc: Vasiliy Kulikov Cc: Alexey Dobriyan Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 5 +++++ fs/proc/array.c | 20 +++++++++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index d8d3f9a8e5a3..fb0a6aeb936c 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -311,6 +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 diff --git a/fs/proc/array.c b/fs/proc/array.c index 62887e39a2de..c1c207c36cae 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -517,9 +517,23 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task)); seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime)); seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime)); - seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_data : 0); - seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->end_data : 0); - seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_brk : 0); + + if (mm && permitted) { + seq_put_decimal_ull(m, ' ', mm->start_data); + seq_put_decimal_ull(m, ' ', mm->end_data); + seq_put_decimal_ull(m, ' ', mm->start_brk); + seq_put_decimal_ull(m, ' ', mm->arg_start); + seq_put_decimal_ull(m, ' ', mm->arg_end); + seq_put_decimal_ull(m, ' ', mm->env_start); + seq_put_decimal_ull(m, ' ', mm->env_end); + } else + seq_printf(m, " 0 0 0 0 0 0 0"); + + if (permitted) + seq_put_decimal_ll(m, ' ', task->exit_code); + else + seq_put_decimal_ll(m, ' ', 0); + seq_putc(m, '\n'); if (mm) mmput(mm); -- cgit v1.2.3