Messages in this thread | | | Date | Wed, 13 Sep 2017 19:48:04 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] prctl: add PR_[GS]ET_PDEATHSIG_PROC |
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On 09/13, Jürg Billeter wrote: > > On Wed, 2017-09-13 at 19:11 +0200, Oleg Nesterov wrote: > > On 09/12, Jürg Billeter wrote: > > > > > > On Tue, 2017-09-12 at 19:05 +0200, Oleg Nesterov wrote: > > > > On 09/09, Jürg Billeter wrote: > > > > > Unlike > > > > > PR_SET_PDEATHSIG, this is inherited across fork to allow killing a whole > > > > > subtree without race conditions. > > > > > > > > but I am still not sure this is right... at least I can't understand the > > > > "without race conditions" above. > > > > > > > > IOW, the child can do prctl(PR_SET_PDEATHSIG_PROC, SIGKILL) right after fork(), > > > > why this is not enough to kill a whole subtree without race conditions? > > > > > > What if the parent dies between fork() and prctl()? > > > > The child will be killed? Sorry, can't understand... > > If PR_SET_PDEATHSIG_PROC was not inherited across fork and the parent > died between fork() and prctl(PR_SET_PDEATHSIG_PROC, SIGKILL) in the > child, the child would not be killed.
Aah, sorry. I forgot about another oddity of pdeath_signal API...
Somehow I misread this patch as if reparent_leader() looks at current->signal->pdeath_signal_proc, not child->signal->pdeath_signal_proc. And to me the former makes more sense. But I won't insist.
Oleg.
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