linux-toradex.git/kernel/sys.c, branch v2.6.25-rc2

Pidns: make full use of xxx_vnr() calls

2008-02-08T17:22:29+00:00

Some time ago the xxx_vnr() calls (e.g.  pid_vnr or find_task_by_vpid) were
_all_ converted to operate on the current pid namespace.  After this each call
like xxx_nr_ns(foo, current->nsproxy->pid_ns) is nothing but a xxx_vnr(foo)
one.

Switch all the xxx_nr_ns() callers to use the xxx_vnr() calls where
appropriate.

Signed-off-by: Pavel Emelyanov 
Reviewed-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sys_getsid: don't use ->nsproxy directly

2008-02-08T17:22:28+00:00

With the new semantics of find_vpid() we don't need to play with ->nsproxy
explicitely, _vxx() do the right things.

Also s/tasklist/rcu/.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sys_setsid: remove now unneeded session != 1 check

2008-02-08T17:22:27+00:00

Eric's "fix clone(CLONE_NEWPID)" eliminated the last reason for this hack.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

start the global /sbin/init with 0,0 special pids

2008-02-08T17:22:27+00:00

As Eric pointed out, there is no problem with init starting with sid == pgid
== 0, and this was historical linux behavior changed in 2.6.18.

Remove kernel_init()->__set_special_pids(), this is unneeded and complicates
the rules for sys_setsid().

This change and the previous change in daemonize() mean that /sbin/init does
not need the special "session != 1" hack in sys_setsid() any longer. We can't
remove this check yet, we should cleanup copy_process(CLONE_NEWPID) first, so
update the comment only.

Signed-off-by: Oleg Nesterov 
Acked-by: "Eric W. Biederman" 
Cc: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

teach set_special_pids() to use struct pid

2008-02-08T17:22:27+00:00

Change set_special_pids() to work with struct pid, not pid_t from global name
space. This again speedups and imho cleanups the code, also a preparation for
the next patch.

Signed-off-by: Oleg Nesterov 
Acked-by: "Eric W. Biederman" 
Acked-by: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fix setsid() for sub-namespace /sbin/init

2008-02-08T17:22:27+00:00

sys_setsid() still deals with pid_t's from the global namespace. This means
that the "session > 1" check can't help for sub-namespace init, setsid() can't
succeed because copy_process(CLONE_NEWPID) populates PIDTYPE_PGID/SID links.

Remove the usage of task_struct->pid and convert the code to use "struct pid".
This also simplifies and speedups the code, saves one find_pid().

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Acked-by: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sys_setpgid(): simplify pid/ns interaction

2008-02-08T17:22:27+00:00

sys_setpgid() does unneeded conversions from pid_t to "struct pid" and vice
versa.  Use "struct pid" more consistently.  Saves one find_vpid() and
eliminates the explicit usage of ->nsproxy->pid_ns.  Imho, cleanups the
code.

Also use the same_thread_group() helper.

Signed-off-by: Oleg Nesterov 
Acked-by: Pavel Emelyanov 
Acked-by: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/sys.c: get rid of expensive divides in groups_sort()

2008-02-06T18:41:09+00:00

groups_sort() can be quite long if user loads a large gid table.

This is because GROUP_AT(group_info, some_integer) uses an integer divide.
So having to do XXX thousand divides during one syscall can lead to very
high latencies.  (NGROUPS_MAX=65536)

In the past (25 Mar 2006), an analog problem was found in groups_search()
(commit d74beb9f33a5f16d2965f11b275e401f225c949d ) and at that time I
changed some variables to unsigned int.

I believe that a more generic fix is to make sure NGROUPS_PER_BLOCK is
unsigned.

Signed-off-by: Eric Dumazet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

get rid of NR_OPEN and introduce a sysctl_nr_open

2008-02-06T18:41:06+00:00

NR_OPEN (historically set to 1024*1024) actually forbids processes to open
more than 1024*1024 handles.

Unfortunatly some production servers hit the not so 'ridiculously high
value' of 1024*1024 file descriptors per process.

Changing NR_OPEN is not considered safe because of vmalloc space potential
exhaust.

This patch introduces a new sysctl (/proc/sys/fs/nr_open) wich defaults to
1024*1024, so that admins can decide to change this limit if their workload
needs it.

[akpm@linux-foundation.org: export it for sparc64]
Signed-off-by: Eric Dumazet 
Cc: Alan Cox 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: "David S. Miller" 
Cc: Ralf Baechle 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

make kernel_shutdown_prepare() static

2008-02-05T17:44:22+00:00

kernel_shutdown_prepare() can now become static.

Signed-off-by: Adrian Bunk 
Acked-by: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds