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Date: Sat, 25 Jun 2011 15:43:50 +0200 From: Tejun Heo <tj@...nel.org> To: Oleg Nesterov <oleg@...hat.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org>, vda.linux@...glemail.com, jan.kratochvil@...hat.com, pedro@...esourcery.com, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/3] ptrace: ptrace_reparented() should check same_thread_group() Hello, On Fri, Jun 24, 2011 at 05:34:06PM +0200, Oleg Nesterov wrote: > exit_notify: we should respect ->exit_signal if the exiting leader > is traced by any thread from the parent thread group. It is the > child of the whole group, and we are going to send the signal to > the whole group. This seems correct. > wait_task_zombie: without __WNOTHREAD do_wait() should do the same > for any thread, only sys_ptrace() is "bound" to the single thread. > However do_wait(WEXITED) succeeds but does not release a traced > natural child unless the caller is the tracer. > > Test-case: ... > Note that the main thread simply does > > pid = fork(); > kill(pid, SIGKILL); > > and then without the patch wait4(WEXITED) succeeds twice and reports > WTERMSIG(stat) == SIGKILL. This latter one is interesting to say the least. Yes, wait(2) is process-wide operation and should behave identically when for all threads in the same process. > Signed-off-by: Oleg Nesterov <oleg@...hat.com> This patch involves very subtle behavior change when the tracer is multi-threaded && real parent of the tracee. Slightly worrisome but it is a bug fix and extremely fringe, so... Acked-by: Tejun Heo <tj@...nel.org> Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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