linux-toradex.git/kernel/exit.c, branch tegra-10.9.9

connector: fix regression introduced by sid connector

2009-10-29T14:39:25+00:00

Since commit 02b51df1b07b4e9ca823c89284e704cadb323cd1 (proc connector: add
event for process becoming session leader) we have the following warning:

Badness at kernel/softirq.c:143
[...]
Krnl PSW : 0404c00180000000 00000000001481d4 (local_bh_enable+0xb0/0xe0)
[...]
Call Trace:
([<000000013fe04100>] 0x13fe04100)
 [<000000000048a946>] sk_filter+0x9a/0xd0
 [<000000000049d938>] netlink_broadcast+0x2c0/0x53c
 [<00000000003ba9ae>] cn_netlink_send+0x272/0x2b0
 [<00000000003baef0>] proc_sid_connector+0xc4/0xd4
 [<0000000000142604>] __set_special_pids+0x58/0x90
 [<0000000000159938>] sys_setsid+0xb4/0xd8
 [<00000000001187fe>] sysc_noemu+0x10/0x16
 [<00000041616cb266>] 0x41616cb266

The warning is
--->    WARN_ON_ONCE(in_irq() || irqs_disabled());

The network code must not be called with disabled interrupts but
sys_setsid holds the tasklist_lock with spinlock_irq while calling the
connector.

After a discussion we agreed that we can move proc_sid_connector from
__set_special_pids to sys_setsid.

We also agreed that it is sufficient to change the check from
task_session(curr) != pid into err > 0, since if we don't change the
session, this means we were already the leader and return -EPERM.

One last thing:
There is also daemonize(), and some people might want to get a
notification in that case. Since daemonize() is only needed if a user
space does kernel_thread this does not look important (and there seems
to be no consensus if this connector should be called in daemonize). If
we really want this, we can add proc_sid_connector to daemonize() in an
additional patch (Scott?)

Signed-off-by: Christian Borntraeger 
Cc: Scott James Remnant 
Cc: Matt Helsley 
Cc: David S. Miller 
Acked-by: Oleg Nesterov 
Acked-by: Evgeniy Polyakov 
Acked-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-10-08T19:16:35+00:00

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  futex: fix requeue_pi key imbalance
  futex: Fix typo in FUTEX_WAIT/WAKE_BITSET_PRIVATE definitions
  rcu: Place root rcu_node structure in separate lockdep class
  rcu: Make hot-unplugged CPU relinquish its own RCU callbacks
  rcu: Move rcu_barrier() to rcutree
  futex: Move exit_pi_state() call to release_mm()
  futex: Nullify robust lists after cleanup
  futex: Fix locking imbalance
  panic: Fix panic message visibility by calling bust_spinlocks(0) before dying
  rcu: Replace the rcu_barrier enum with pointer to call_rcu*() function
  rcu: Clean up code based on review feedback from Josh Triplett, part 4
  rcu: Clean up code based on review feedback from Josh Triplett, part 3
  rcu: Fix rcu_lock_map build failure on CONFIG_PROVE_LOCKING=y
  rcu: Clean up code to address Ingo's checkpatch feedback
  rcu: Clean up code based on review feedback from Josh Triplett, part 2
  rcu: Clean up code based on review feedback from Josh Triplett

futex: Move exit_pi_state() call to release_mm()

2009-10-06T15:00:01+00:00

exit_pi_state() is called from do_exit() but not from do_execve().
Move it to release_mm() so it gets called from do_execve() as well.

Signed-off-by: Thomas Gleixner 
LKML-Reference: 
Cc: stable@kernel.org
Cc: Anirban Sinha 
Cc: Peter Zijlstra

task_struct cleanup: move binfmt field to mm_struct

2009-09-24T14:21:05+00:00

Because the binfmt is not different between threads in the same process,
it can be moved from task_struct to mm_struct.  And binfmt moudle is
handled per mm_struct instead of task_struct.

Signed-off-by: Hiroshi Shimamoto 
Acked-by: Oleg Nesterov 
Cc: Rusty Russell 
Acked-by: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

wait_noreap_copyout(): check for ->wo_info != NULL

2009-09-24T14:21:00+00:00

Current behaviour of sys_waitid() looks odd.  If user passes infop ==
NULL, sys_waitid() returns success.  When user additionally specifies flag
WNOWAIT, sys_waitid() returns -EFAULT on the same conditions.  When user
combines WNOWAIT with WCONTINUED, sys_waitid() again returns success.

This patch adds check for ->wo_info in wait_noreap_copyout().

User-visible change: starting from this commit, sys_waitid() always checks
infop != NULL and does not fail if it is NULL.

Signed-off-by: Vitaly Mayatskikh 
Reviewed-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

do_wait: fix sys_waitid()-specific behaviour

2009-09-24T14:21:00+00:00

do_wait() checks ->wo_info to figure out who is the caller.  If it's not
NULL the caller should be sys_waitid(), in that case do_wait() fixes up
the retval or zeros ->wo_info, depending on retval from underlying
function.

This is bug: user can pass ->wo_info == NULL and sys_waitid() will return
incorrect value.

man 2 waitid says:

	waitid(): returns 0 on success

Test-case:

	int main(void)
	{
		if (fork())
			assert(waitid(P_ALL, 0, NULL, WEXITED) == 0);

		return 0;
	}

Result:

	Assertion `waitid(P_ALL, 0, ((void *)0), 4) == 0' failed.

Move that code to sys_waitid().

User-visible change: sys_waitid() will return 0 on success, either
infop is set or not.

Note, there's another bug in wait_noreap_copyout() which affects
return value of sys_waitid(). It will be fixed in next patch.

Signed-off-by: Vitaly Mayatskikh 
Reviewed-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

wait_consider_task: kill "parent" argument

2009-09-24T14:21:00+00:00

Kill the unused "parent" argument in wait_consider_task(), it was never used.

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Cc: Ingo Molnar 
Cc: Ratan Nalumasu 
Cc: Vitaly Mayatskikh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

do_wait-wakeup-optimization: simplify task_pid_type()

2009-09-24T14:21:00+00:00

task_pid_type() is only used by eligible_pid() which has to check wo_type
!= PIDTYPE_MAX anyway.  Remove this check from task_pid_type() and factor
out ->pids[type] access, this shrinks .text a bit and simplifies the code.

The matches the behaviour of other similar helpers, say get_task_pid().
The caller must ensure that pid_type is valid, not the callee.

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage

2009-09-24T14:21:00+00:00

child_wait_callback()->eligible_child() is not right, we can miss the
wakeup if the task was detached before __wake_up_parent() and the caller
of do_wait() didn't use __WALL.

Move ->wo_pid checks from eligible_child() to the new helper,
eligible_pid(), and change child_wait_callback() to use it instead of
eligible_child().

Note: actually I think it would be better to fix the __WCLONE check in
eligible_child(), it doesn't look exactly right.  But it is not clear what
is the supposed behaviour, and any change is user-visible.

Reported-by: KAMEZAWA Hiroyuki 
Tested-by: KAMEZAWA Hiroyuki 
Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

do_wait() wakeup optimization: child_wait_callback: check __WNOTHREAD case

2009-09-24T14:21:00+00:00

Suggested by Roland.

do_wait(__WNOTHREAD) can only succeed if the caller is either ptracer, or
it is ->real_parent and the child is not traced. IOW, caller == p->parent
otherwise we should not wake up.

Change child_wait_callback() to check this. Ratan reports the workload with
CPU load >99% caused by unnecessary wakeups, should be fixed by this patch.

Signed-off-by: Oleg Nesterov 
Acked-by: Roland McGrath 
Cc: Ingo Molnar 
Cc: Ratan Nalumasu 
Cc: Vitaly Mayatskikh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds