user/sven/linux.git/kernel/exit.c, branch v2.6.25.2

asmlinkage_protect replaces prevent_tail_call

2008-04-11T00:28:26Z

The prevent_tail_call() macro works around the problem of the compiler clobbering argument words on the stack, which for asmlinkage functions is the caller's (user's) struct pt_regs. The tail/sibling-call optimization is not the only way that the compiler can decide to use stack argument words as scratch space, which we have to prevent. Other optimizations can do it too. Until we have new compiler support to make "asmlinkage" binding on the compiler's own use of the stack argument frame, we have work around all the manifestations of this issue that crop up. More cases seem to be prevented by also keeping the incoming argument variables live at the end of the function. This makes their original stack slots attractive places to leave those variables, so the compiler tends not clobber them for something else. It's still no guarantee, but it handles some observed cases that prevent_tail_call() did not. Signed-off-by: Roland McGrath Signed-off-by: Linus Torvalds

Fix waitid si_code regression

2008-03-08T19:54:00Z

In commit ee7c82da830ea860b1f9274f1f0cdf99f206e7c2 ("wait_task_stopped: simplify and fix races with SIGCONT/SIGKILL/untrace"), the magic (short) cast when storing si_code was lost in wait_task_stopped. This leaks the in-kernel CLD_* values that do not match what userland expects. Signed-off-by: Roland McGrath Cc: Oleg Nesterov Signed-off-by: Linus Torvalds

exit_notify: fix kill_orphaned_pgrp() usage with mt exit

2008-03-03T22:53:16Z

1. exit_notify() always calls kill_orphaned_pgrp(). This is wrong, we should do this only when the whole process exits. 2. exit_notify() uses "current" as "ignored_task", obviously wrong. Use ->group_leader instead. Test case: void hup(int sig) { printf("HUP received\n"); } void *tfunc(void *arg) { sleep(2); printf("sub-thread exited\n"); return NULL; } int main(int argc, char *argv[]) { if (!fork()) { signal(SIGHUP, hup); kill(getpid(), SIGSTOP); exit(0); } pthread_t thr; pthread_create(&thr, NULL, tfunc, NULL); sleep(1); printf("main thread exited\n"); syscall(__NR_exit, 0); return 0; } output: main thread exited HUP received Hangup With this patch the output is: main thread exited sub-thread exited HUP received Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

will_become_orphaned_pgrp: partially fix insufficient ->exit_state check

2008-03-03T22:53:16Z

p->exit_state != 0 doesn't mean this process is dead, it may have sub-threads. Change the code to use "p->exit_state && thread_group_empty(p)" instead. Without this patch, ^Z doesn't deliver SIGTSTP to the foreground process if the main thread has exited. However, the new check is not perfect either. There is a window when exit_notify() drops tasklist and before release_task(). Suppose that the last (non-leader) thread exits. This means that entire group exits, but thread_group_empty() is not true yet. As Eric pointed out, is_global_init() is wrong as well, but I did not dare to do other changes. Just for the record, has_stopped_jobs() is absolutely wrong too. But we can't fix it now, we should first fix SIGNAL_STOP_STOPPED issues. Even with this patch ^Z doesn't play well with the dead main thread. The task is stopped correctly but do_wait(WSTOPPED) won't see it. This is another unrelated issue, will be (hopefully) fixed separately. Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

introduce kill_orphaned_pgrp() helper

2008-03-03T22:53:16Z

Factor out the common code in reparent_thread() and exit_notify(). No functional changes. Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

Use struct path in fs_struct

2008-02-15T05:13:33Z

* Use struct path in fs_struct. Signed-off-by: Andreas Gruenbacher Signed-off-by: Jan Blunck Acked-by: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel: remove fastcall in kernel/*

2008-02-08T17:22:31Z

[akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Harvey Harrison Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Pidns: make full use of xxx_vnr() calls

2008-02-08T17:22:29Z

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

pid: sys_wait... fixes

2008-02-08T17:22:27Z

This modifies do_wait and eligible child to take a pair of enum pid_type and struct pid *pid to precisely specify what set of processes are eligible to be waited for, instead of the raw pid_t value from sys_wait4. This fixes a bug in sys_waitid where you could not wait for children in just process group 1. This fixes a pid namespace crossing case in eligible_child. Allowing us to wait for a processes in our current process group even if our current process group == 0. This allows the no child with this pid case to be optimized. This allows us to optimize the pid membership test in eligible child to be optimized. This even closes a theoretical pid wraparound race where in a threaded parent if two threads are waiting for the same child and one thread picks up the child and the pid numbers wrap around and generate another child with that same pid before the other thread is scheduled (teribly insanely unlikely) we could end up waiting on the second child with the same pid# and not discover that the specific child we were waiting for has exited. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Eric W. Biederman Cc: Oleg Nesterov Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

move the related code from exit_notify() to exit_signals()

2008-02-08T17:22:27Z

The previous bugfix was not optimal, we shouldn't care about group stop when we are the only thread or the group stop is in progress. In that case nothing special is needed, just set PF_EXITING and return. Also, take the related "TIF_SIGPENDING re-targeting" code from exit_notify(). So, from the performance POV the only difference is that we don't trust !signal_pending() until we take ->siglock. But this in fact fixes another ___pure___ theoretical minor race. __group_complete_signal() finds the task without PF_EXITING and chooses it as the target for signal_wake_up(). But nothing prevents this task from exiting in between without noticing the pending signal and thus unpredictably delaying the actual delivery. Signed-off-by: Oleg Nesterov Cc: Davide Libenzi Cc: Ingo Molnar Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds