- 26 7月, 2008 1 次提交
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由 Oleg Nesterov 提交于
There is no reason for rcu_read_lock() in __exit_signal(). tsk->sighand can only be changed if tsk does exec, obviously this is not possible. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 17 7月, 2008 4 次提交
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由 Roland McGrath 提交于
This fixes an arcane bug that we think was a regression introduced by commit b2b2cbc4. When a parent ignores SIGCHLD (or uses SA_NOCLDWAIT), its children would self-reap but they don't if it's using ptrace on them. When the parent thread later exits and ceases to ptrace a child but leaves other live threads in the parent's thread group, any zombie children are left dangling. The fix makes them self-reap then, as they would have done earlier if ptrace had not been in use. Signed-off-by: NRoland McGrath <roland@redhat.com>
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由 Roland McGrath 提交于
This reverts the effect of commit f2cc3eb1 "do_wait: fix security checks". That change reverted the effect of commit 73243284. The rationale for the original commit still stands. The inconsistent treatment of children hidden by ptrace was an unintended omission in the original change and in no way invalidates its purpose. This makes do_wait return the error returned by security_task_wait() (usually -EACCES) in place of -ECHILD when there are some children the caller would be able to wait for if not for the permission failure. A permission error will give the user a clue to look for security policy problems, rather than for mysterious wait bugs. Signed-off-by: NRoland McGrath <roland@redhat.com>
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由 Roland McGrath 提交于
ptrace no longer fiddles with the children/sibling links, and the old ptrace_children list is gone. Now ptrace, whether of one's own children or another's via PTRACE_ATTACH, just uses the new ptraced list instead. There should be no user-visible difference that matters. The only change is the order in which do_wait() sees multiple stopped children and stopped ptrace attachees. Since wait_task_stopped() was changed earlier so it no longer reorders the children list, we already know this won't cause any new problems. Signed-off-by: NRoland McGrath <roland@redhat.com>
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由 Roland McGrath 提交于
This breaks out the guts of do_wait into three subfunctions. The control flow is less nonobvious without so much goto. do_wait_thread and ptrace_do_wait contain the main work of the outer loop. wait_consider_task contains the main work of the inner loop. Signed-off-by: NRoland McGrath <roland@redhat.com>
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- 03 7月, 2008 1 次提交
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由 Jens Axboe 提交于
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 25 5月, 2008 1 次提交
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由 Oleg Nesterov 提交于
__exit_signal() does flush_sigqueue(tsk->pending) outside of ->siglock. This can race with another thread doing sigqueue_free(), we can free the same SIGQUEUE_PREALLOC sigqueue twice or corrupt the pending->list. Note that even sys_exit_group() can trigger this race, not only sys_timer_delete(). Move the callsite of flush_sigqueue(tsk->pending) under ->siglock. This patch doesn't touch flush_sigqueue(->shared_pending) below, it is called when there are no other threads which can play with signals, and sigqueue_free() can't be used outside of our thread group. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: NRoland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 02 5月, 2008 1 次提交
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由 Al Viro 提交于
Initial splitoff of the low-level stuff; taken to fdtable.h Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 30 4月, 2008 6 次提交
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由 Oleg Nesterov 提交于
Use change_pid() instead of detach_pid() + attach_pid() in __set_special_pids(). This way task_session() is not NULL in between. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Add another trivial helper for the sake of grep. It also auto-documents the fact that ->parent != real_parent implies ->ptrace. No functional changes. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: NRoland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Add a couple of small comments, it is not easy to see what this code does. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Trivial, use same_thread_group() in reparent_thread(). Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
exit.c has numerous "->exit_signal == -1" comparisons, this check is subtle and deserves a helper. Imho makes the code more parseable for humans. At least it's surely more greppable. Also, a couple of whitespace cleanups. No functional changes. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
do_group_exit() checks SIGNAL_GROUP_EXIT to avoid taking sighand->siglock. Since ed5d2cac exec() doesn't set this flag, we should use signal_group_exit(). This is not needed for correctness, but can speedup the multithreaded exec and makes the code more consistent. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 29 4月, 2008 1 次提交
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由 Balbir Singh 提交于
Remove the mem_cgroup member from mm_struct and instead adds an owner. This approach was suggested by Paul Menage. The advantage of this approach is that, once the mm->owner is known, using the subsystem id, the cgroup can be determined. It also allows several control groups that are virtually grouped by mm_struct, to exist independent of the memory controller i.e., without adding mem_cgroup's for each controller, to mm_struct. A new config option CONFIG_MM_OWNER is added and the memory resource controller selects this config option. This patch also adds cgroup callbacks to notify subsystems when mm->owner changes. The mm_cgroup_changed callback is called with the task_lock() of the new task held and is called just prior to changing the mm->owner. I am indebted to Paul Menage for the several reviews of this patchset and helping me make it lighter and simpler. This patch was tested on a powerpc box, it was compiled with both the MM_OWNER config turned on and off. After the thread group leader exits, it's moved to init_css_state by cgroup_exit(), thus all future charges from runnings threads would be redirected to the init_css_set's subsystem. Signed-off-by: NBalbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Hirokazu Takahashi <taka@valinux.co.jp> Cc: David Rientjes <rientjes@google.com>, Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: NPekka Enberg <penberg@cs.helsinki.fi> Reviewed-by: NPaul Menage <menage@google.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 28 4月, 2008 1 次提交
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由 Lee Schermerhorn 提交于
This is a change that was requested some time ago by Mel Gorman. Makes sense to me, so here it is. Note: I retain the name "mpol_free_shared_policy()" because it actually does free the shared_policy, which is NOT a reference counted object. However, ... The mempolicy object[s] referenced by the shared_policy are reference counted, so mpol_put() is used to release the reference held by the shared_policy. The mempolicy might not be freed at this time, because some task attached to the shared object associated with the shared policy may be in the process of allocating a page based on the mempolicy. In that case, the task performing the allocation will hold a reference on the mempolicy, obtained via mpol_shared_policy_lookup(). The mempolicy will be freed when all tasks holding such a reference have called mpol_put() for the mempolicy. Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andi Kleen <ak@suse.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 25 4月, 2008 2 次提交
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由 Al Viro 提交于
* let unshare_files() give caller the displaced files_struct * don't bother with grabbing reference only to drop it in the caller if it hadn't been shared in the first place * in that form unshare_files() is trivially implemented via unshare_fd(), so we eliminate the duplicate logics in fork.c * reset_files_struct() is not just only called for current; it will break the system if somebody ever calls it for anything else (we can't modify ->files of somebody else). Lose the task_struct * argument. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
* unshare_files() can fail; doing it after irreversible actions is wrong and de_thread() is certainly irreversible. * since we do it unconditionally anyway, we might as well do it in do_execve() and save ourselves the PITA in binfmt handlers, etc. * while we are at it, binfmt_som actually leaked files_struct on failure. As a side benefit, unshare_files(), put_files_struct() and reset_files_struct() become unexported. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 23 4月, 2008 1 次提交
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由 Al Viro 提交于
The only reason to have separated __...() for those was to keep them inlined for local users in exit.c. Since Alexey removed the inline on those, there's no reason whatsoever to keep them around; just collapse with normal variants. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 11 4月, 2008 1 次提交
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由 Roland McGrath 提交于
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: NRoland McGrath <roland@redhat.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 3月, 2008 1 次提交
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由 Roland McGrath 提交于
In commit ee7c82da ("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: NRoland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 04 3月, 2008 3 次提交
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Factor out the common code in reparent_thread() and exit_notify(). No functional changes. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 15 2月, 2008 1 次提交
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由 Jan Blunck 提交于
* Use struct path in fs_struct. Signed-off-by: NAndreas Gruenbacher <agruen@suse.de> Signed-off-by: NJan Blunck <jblunck@suse.de> Acked-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 2月, 2008 15 次提交
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由 Harvey Harrison 提交于
[akpm@linux-foundation.org: coding-style fixes] Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com> Acked-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Pavel Emelyanov 提交于
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: NPavel Emelyanov <xemul@openvz.org> Reviewed-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Eric W. Biederman 提交于
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: NEric W. Biederman <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
do_signal_stop() counts all sub-thread and sets ->group_stop_count accordingly. Every thread should decrement ->group_stop_count and stop, the last one should notify the parent. However a sub-thread can exit before it notices the signal_pending(), or it may be somewhere in do_exit() already. In that case the group stop never finishes properly. Note: this is a minimal fix, we can add some optimizations later. Say we can return quickly if thread_group_empty(). Also, we can move some signal related code from exit_notify() to exit_signals(). Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: NDavide Libenzi <davidel@xmailserver.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Daemonized kernel threads run in the init's session. This doesn't match the behaviour of kthread_create()'ed threads, and this is one of the 2 reasons why we need a special hack in sys_setsid(). Now that set_special_pids() was changed to use struct pid, not pid_t, we can use init_struct_pid and set 0,0 special pids. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com> Acked-by: NPavel Emelyanov <xemul@openvz.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
The first "p->exit_state != EXIT_ZOMBIE" check doesn't make too much sense. The exit_state was EXIT_ZOMBIE when the function was called, and another thread can change it to EXIT_DEAD right after the check. The second condition is not possible, detached non-traced threads were already filtered out by eligible_child(), we didn't drop tasklist since then. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Surprise, the other two wait_task_*() functions also abuse the task_pid_nr_ns() function, and may cause read-after-free or report nr == 0 in wait_task_continued(). wait_task_zombie() doesn't have this problem, but it is still better to cache pid_t rather than call task_pid_nr_ns() three times on the saved pid_namespace. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Imho, the current usage of security_task_wait() is not logical. Suppose we have the single child p, and security_task_wait(p) return -EANY. In that case waitpid(-1) returns this error. Why? Isn't it better to return ECHLD? We don't really have reapable children. Now suppose that child was stolen by gdb. In that case we find this child on ->ptrace_children and set flag = 1, but we don't check that the child was denied. So, do_wait(..., WNOHANG) returns 0, this doesn't match the behaviour above. Without WNOHANG do_wait() blocks only to return the error later, when the child will be untraced. Inho, really strange. I think eligible_child() should return the error only if the child's pid was requested explicitly, otherwise we should silently ignore the tasks which were nacked by security_task_wait(). Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
eligible_child() == 2 means delay_group_leader(). With the previous patch this only matters for EXIT_ZOMBIE task, we can move that special check to the only place it is really needed. Also, with this patch we don't skip security_task_wait() for the group leaders in a non-empty thread group. I don't really understand the exact semantics of security_task_wait(), but imho this change is a bugfix. Also rearrange the code a bit to kill an ugly "check_continued" backdoor. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
wait_task_stopped() doesn't need the "delay_group_leader" parameter. If the child is not traced it must be a group leader. With or without subthreads ->group_stop_count == 0 when the whole task is stopped. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Mika Penttila <mika.penttila@kolumbus.fi> Acked-by: NRoland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Every branch if the main "if" statement does the same code at the end. Move it down. Also, fix the indentation. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
wait_task_stopped() has multiple races with SIGCONT/SIGKILL. tasklist_lock does not pin the child in TASK_TRACED/TASK_STOPPED stated, almost all info reported (including exit_code) may be wrong. In fact, the code under write_lock_irq(tasklist_lock) is not safe. The child may be PTRACE_DETACH'ed at this time by another subthread, in that case it is possible we are no longer its ->parent. Change wait_task_stopped() to take ->siglock before inspecting the task. This guarantees that the child can't resume and (for example) clear its ->exit_code, so we don't need to use xchg(&p->exit_code) and re-check. The only exception is ptrace_stop() which changes ->state and ->exit_code without ->siglock held during abort. But this can only happen if both the tracer and the tracee are dying (coredump is in progress), we don't care. With this patch wait_task_stopped() doesn't move the child to the end of the ->parent list on success. This optimization could be restored, but in that case we have to take write_lock(tasklist) and do some nasty checks. Also change the do_wait() since we don't return EAGAIN any longer. [akpm@linux-foundation.org: fix up after Willy renamed everything] Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Oleg Nesterov 提交于
Now that my_ptrace_child() is trivial we can use the "p->ptrace & PT_PTRACED" inline and simplify the corresponding logic in do_wait: we can't find the child in TASK_TRACED state without PT_PTRACED flag set, ptrace_untrace() either sets TASK_STOPPED or wakes up the tracee. Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: NRoland McGrath <roland@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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