- 02 Apr, 2006 1 commit
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Dave Jones authored
< 0 checks on unsigned variables are pointless. Signed-off-by:Dave Jones <davej@redhat.com>
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- 29 Mar, 2006 39 commits
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Dave Jones authored
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Dave Jones authored
Snipped from an otherwise rejected patch by Jan Beulich <jbeulich@novell.com> Signed-off-by: -
Linus Torvalds authored
* 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/scjody/ieee1394: ohci1394: cleanup the "Unexpected PCI resource length" warning. sbp2: misc debug logging cleanups sbp2: proper treatment of DID_OK ieee1394: set read permission for parameter disable_irm sbp2: check for ARM failure ohci1394: clean up asynchronous and physical request filters programming ieee1394: remove amdtp remains from ieee1394_core.h ieee1394: remove devfs support Signed-off-by:Jody McIntyre <scjody@modernduck.com> sbp2: prevent unloading of 1394 low-level driver
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Oleg Nesterov authored
send_sigqueue() checks PF_EXITING, then locks p->sighand->siglock. This is unsafe: 'p' can exit in between and set ->sighand = NULL. The race is theoretical, the window is tiny and irqs are disabled by the caller, so I don't think we need the fix for -stable tree. Convert send_sigqueue() to use lock_task_sighand() helper. Also, delete 'p->flags & PF_EXITING' re-check, it is unneeded and the comment is wrong. Signed-off-by:
Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
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Oleg Nesterov authored
The previous patch has changed callsites of do_notify_parent_cldstop() so that to_self == (->ptrace & PT_PTRACED) always (as it should be). We can remove this parameter now. Signed-off-by:
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Oleg Nesterov authored
Remove an obscure 'stop_count < 0' check in finish_stop(). The previous patch made this case impossible. Signed-off-by:
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Oleg Nesterov authored
do_signal_stop() considers 'thread_group_empty()' as a special case. This was needed to avoid taking tasklist_lock. Since this lock is unneeded any longer, we can remove this special case and simplify the code even more. Also, before this patch, finish_stop() was called with stop_count == -1 for 'thread_group_empty()' case. This is not strictly wrong, but confusing and unneeded. Signed-off-by:
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Oleg Nesterov authored
Move 'tsk->sighand = NULL' from cleanup_sighand() to __exit_signal(). This makes the exit path more understandable and allows us to do cleanup_sighand() outside of ->siglock protected section. Signed-off-by:
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Oleg Nesterov authored
Eric W. Biederman wrote: > > Ok. SUSV3/Posix is clear, fork is atomic with respect > to signals. Either a signal comes before or after a > fork but not during. (See the rationale section). > http://www.opengroup.org/onlinepubs/000095399/functions/fork.html > > The tasklist_lock does not stop forks from adding to a process > group. The forks stall while the tasklist_lock is held, but a fork > that began before we grabbed the tasklist_lock simply completes > afterwards, and the child does not receive the signal. This also means that SIGSTOP or sig_kernel_coredump() signal can't be delivered to pgrp/session reliably. With this patch copy_process() returns -ERESTARTNOINTR when it detects a pending signal, fork() will be restarted transparently after handling the signals. This patch also deletes now unneeded "group_stop_count > 0" check, copy_process() can no longer succeed while group stop in progress. Signed-off-by:
Eric Biederman <ebiederm@xmission.com> Signed-off-by:
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Oleg Nesterov authored
This patch kills PIDTYPE_TGID pid_type thus saving one hash table in kernel/pid.c and speeding up subthreads create/destroy a bit. It is also a preparation for the further tref/pids rework. This patch adds 'struct list_head thread_group' to 'struct task_struct' instead. We don't detach group leader from PIDTYPE_PID namespace until another thread inherits it's ->pid == ->tgid, so we are safe wrt premature free_pidmap(->tgid) call. Currently there are no users of find_task_by_pid_type(PIDTYPE_TGID). Should the need arise, we can use find_task_by_pid()->group_leader. Signed-off-by:
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Oleg Nesterov authored
do_sigaction() does not need tasklist_lock anymore, we can simplify the code. Signed-off-by:
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Oleg Nesterov authored
do_group_exit() takes tasklist_lock for zap_other_threads(), this is unneeded now. Signed-off-by:
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Oleg Nesterov authored
do_signal_stop() does not need tasklist_lock anymore. So it does not need to do misc re-checks, and we can simplify the code. Signed-off-by:
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Oleg Nesterov authored
handle_stop_signal() does not need tasklist_lock for SIG_KERNEL_STOP_MASK signals anymore. Signed-off-by:
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Oleg Nesterov authored
sys_times: don't take tasklist_lock Signed-off-by:
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Oleg Nesterov authored
This patch moves __unhash_process() call from realease_task() to __exit_signal(), so __detach_pid() is called with ->siglock held. This means we don't need tasklist_lock to iterate over thread group anymore: copy_process() was already changed to do attach_pid() under ->siglock. Eric's "pidhash-kill-switch_exec_pids.patch" from -mm changed de_thread() so it doesn't touch PIDTYPE_TGID. NOTE: de_thread() still needs some attention. It still changes task->pid lockless. Taking ->sighand.siglock here allows to do more tasklist_lock removals. Signed-off-by:
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Oleg Nesterov authored
This patch reverts 'CONFIG_SMP && thread_group_empty()' optimization in sys_times(). The reason is that the next patch breaks memory ordering which is needed for that optimization. tasklist_lock in sys_times() will be eliminated completely by further patch. Signed-off-by:
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Oleg Nesterov authored
__exit_signal() is private to release_task() now. I think it is better to make it static in kernel/exit.c and export flush_sigqueue() instead - this function is much more simple and straightforward. Signed-off-by:
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Oleg Nesterov authored
Cosmetic, rename __exit_sighand to cleanup_sighand and move it close to copy_sighand(). This matches copy_signal/cleanup_signal naming, and I think it is easier to follow. Signed-off-by:
"Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by:
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Oleg Nesterov authored
This patch factors out duplicated code under 'if' branches. Also, BUG_ON() conversions and whitespace cleanups. Signed-off-by:
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Oleg Nesterov authored
__exit_signal() does important cleanups atomically under ->siglock. It is also called from copy_process's error path. This is not good, for example we can't move __unhash_process() under ->siglock for that reason. We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under 'bad_fork_cleanup_sighand:' label. For copy_process() case it is sufficient to just backout copy_signal(), nothing more. Again, nobody can see this task yet. For CLONE_THREAD case we just decrement signal->count, otherwise nobody can see this ->signal and we can free it lockless. This patch assumes it is safe to do exit_thread_group_keys() without tasklist_lock. Signed-off-by:
David Howells <dhowells@redhat.com> Signed-off-by:
Adrian Bunk <bunk@stusta.de> Signed-off-by:
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Oleg Nesterov authored
The only caller of exit_sighand(tsk) is copy_process's error path. We can call __exit_sighand() directly and kill exit_sighand(). This 'tsk' was not yet registered in pid_hash[] or init_task.tasks, it has no external references, nobody can see it, and IF (clone_flags & CLONE_SIGHAND) At least 'current' has a reference to ->sighand, this means atomic_dec_and_test(sighand->count) can't be true. ELSE Nobody can see this ->sighand, this means we can free it without any locking. Signed-off-by:
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Oleg Nesterov authored
In my opinion this patch cleans up the code. Signed-off-by:
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Oleg Nesterov authored
Add lock_task_sighand() helper and converts group_send_sig_info() to use it. Hopefully we will have more users soon. This patch also removes '!sighand->count' and '!p->usage' checks, I think they both are bogus, racy and unneeded (but probably it makes sense to restore them as BUG_ON()s). ->sighand is cleared and it's ->count is decremented in release_task() with sighand->siglock held, so it is a bug to have '!p->usage || !->count' after we already locked and verified it is the same. On the other hand, an already dead task without ->sighand can have a non-zero ->usage due to ptrace, for example. If we read the stale value of ->sighand we must see the change after spin_lock(), because that change was done while holding that same old ->sighand.siglock. Signed-off-by:
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Oleg Nesterov authored
This patch borrows a clever Hugh's 'struct anon_vma' trick. Without tasklist_lock held we can't trust task->sighand until we locked it and re-checked that it is still the same. But this means we don't need to defer 'kmem_cache_free(sighand)'. We can return the memory to slab immediately, all we need is to be sure that sighand->siglock can't dissapear inside rcu protected section. To do so we need to initialize ->siglock inside ctor function, SLAB_DESTROY_BY_RCU does the rest. Signed-off-by:
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Oleg Nesterov authored
Use ptrace_unlink() instead of open-coding. No changes in kernel/exit.o Signed-off-by:
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Oleg Nesterov authored
Use NULL instead of (... *)0 Signed-off-by:
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Oleg Nesterov authored
Use remove_parent/add_parent instead of open coding. No changes in kernel/exit.o Signed-off-by:
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Oleg Nesterov authored
daemonize() calls set_special_pids(1,1), while init and kernel threads spawned from init/main.c:init() run with 0,0 special pids. This patch changes INIT_SIGNALS() so that that they run with ->pgrp == ->session == 1 also. This patch relies on fact that swapper's pid == 1. Now we have no hashed zero pids in pid_hash[]. User-space visibible change is that now /sbin/init runs with (1,1) special pids and becomes a session leader. Quoting Eric W. Biederman: > > daemonize consuming pids (1,1) then consumes pgrp 1. So that when > /sbin/init calls setsid() it thinks /sbin/init is a process group > leader and setsid() fails. So /sbin/init wants pgrp 1 session 1 > but doesn't get it. I am pretty certain daemonize did not exist so > /sbin/init got pgrp 1 session 1 in 2.4. > > That is the bug that is being fixed. > > This patch takes things one step farther and essentially calls > setsid() for pid == 1 before init is execed. That is new behavior > but it cleans up the kernel as we now do not need to support the > case of a process without a process group or a session. > > The only process that could have possibly cared was /sbin/init > and it already calls setsid() because it doesn't want that. > > If this was going to break anything noticeable the change in behavior > from 2.4 to 2.6 would have already done that. Signed-off-by:
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Oleg Nesterov authored
fork_idle() does unhash_process() just after copy_process(). Contrary, boot_cpu's idle thread explicitely registers itself for each pid_type with nr = 0. copy_process() already checks p->pid != 0 before process_counts++, I think we can just skip attach_pid() calls and job control inits for idle threads and kill unhash_process(). We don't need to cleanup ->proc_dentry in fork_idle() because with this patch idle threads are never hashed in kernel/pid.c:pid_hash[]. We don't need to hash pid == 0 in pidmap_init(). free_pidmap() is never called with pid == 0 arg, so it will never be reused. So it is still possible to use pid == 0 in any PIDTYPE_xxx namespace from kernel/pid.c's POV. However with this patch we don't hash pid == 0 for PIDTYPE_PID case. We still have have PIDTYPE_PGID/PIDTYPE_SID entries with pid == 0: /sbin/init and kernel threads which don't call daemonize(). Signed-off-by:
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Oleg Nesterov authored
Both SET_LINKS() and SET_LINKS/REMOVE_LINKS() have exactly one caller, and these callers already check thread_group_leader(). This patch kills theese macros, they mix two different things: setting process's parent and registering it in init_task.tasks list. Callers are updated to do these actions by hand. Signed-off-by:
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Oleg Nesterov authored
There are places where kernel uses REMOVE_LINKS/SET_LINKS while changing process's ->parent. Use add_parent/remove_parent instead, they don't abuse of global process list. Signed-off-by:
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Oleg Nesterov authored
add_parent(p, parent) is always called with parent == p->parent, and it makes no sense to do it differently. This patch removes this argument. No changes in affected .o files. Signed-off-by:
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Oleg Nesterov authored
'child_reaper' arg is not used in choose_new_parent(). "->exit_state >= EXIT_ZOMBIE" check is a leftover, was valid when EXIT_ZOMBIE lived in ->state var. Signed-off-by:
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Eric W. Biederman authored
switch_exec_pids is only called from de_thread by way of exec, and it is only called when we are exec'ing from a non thread group leader. Currently switch_exec_pids gives the leader the pid of the thread and unhashes and rehashes all of the process groups. The leader is already in the EXIT_DEAD state so no one cares about it's pids. The only concern for the leader is that __unhash_process called from release_task will function correctly. If we don't touch the leader at all we know that __unhash_process will work fine so there is no need to touch the leader. For the task becomming the thread group leader, we just need to give it the pid of the old thread group leader, add it to the task list, and attach it to the session and the process group of the thread group. Currently de_thread is also adding the task to the task list which is just silly. Currently the only leader of __detach_pid besides detach_pid is switch_exec_pids because of the ugly extra work that was being performed. So this patch removes switch_exec_pids because it is doing too much, it is creating an unnecessary special case in pid.c, duing work duplicated in de_thread, and generally obscuring what it is going on. The necessary work is added to de_thread, and it seems to be a little clearer there what is going on. Signed-off-by:
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Eric W. Biederman authored
I'm not really certain what the thinking was but the code obviously wanted to walk processes other than just those in it's session, for purposes of do_SAK. Just walking those tasks that don't have a session assigned sounds at the very least incomplete. So modify the code to kill everything in the session and anything else that might have the tty open. Hopefully this helps if the do_SAK functionality is ever finished. Signed-off-by:
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Eric W. Biederman authored
We already have the tasklist_lock so there is no need for us to reacquire it with send_group_sig_info. reader/writer locks allow multiple readers and thus recursion so the old code was ok just wastful. Signed-off-by:
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Eric W. Biederman authored
The kill_sl function doesn't exist in the kernel so a prototype is completely unnecessary. Signed-off-by:
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Oleg Nesterov authored
I think it is enough to take tasklist_lock for reading while changing child_reaper: Reparenting needs write_lock(tasklist_lock) Only one thread in a thread group can do exec() sighand->siglock garantees that get_signal_to_deliver() will not see a stale value of child_reaper. This means that we can change child_reaper earlier, without calling zap_other_threads() twice. "child_reaper = current" is a NOOP when init does exec from main thread, we don't care. Signed-off-by:
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