From: Mike Christie <michael.christie@oracle.com> To: "Eric W. Biederman" <ebiederm@xmission.com> Cc: axboe@kernel.dk, hdanton@sina.com, mst@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@infradead.org, vverma@digitalocean.com, geert@linux-m68k.org, stefanha@redhat.com, christian.brauner@ubuntu.com Subject: Re: [PATCH V6 01/10] Use copy_process in vhost layer Date: Tue, 18 Jan 2022 12:51:27 -0600 [thread overview] Message-ID: <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> (raw) In-Reply-To: <874k62b76d.fsf@email.froward.int.ebiederm.org> On 1/17/22 11:31 AM, Eric W. Biederman wrote: > Mike Christie <michael.christie@oracle.com> writes: > >> On 12/22/21 12:24 PM, Eric W. Biederman wrote: >>> All I am certain of is that you need to set >>> "args->exit_signal = -1;". This prevents having to play games with >>> do_notify_parent. >> >> Hi Eric, >> >> I have all your review comments handled except this one. It's looking like it's >> more difficult than just setting the exit_signal=-1, so I wanted to check that >> I understood you. > > [snip problems with exit_signal = -1] > >> >> What do you think? > > I was wrong. I appear to have confused the thread and the non-thread > cases. > > Perhaps I meant "args->exit_signal = 0". That looks like > do_notify_parent won't send it, and thread_group_leader continues to do > the right thing. That doesn't work too. exit_notify will call do_notify_parent but our parent, qemu, does not ignore SIGCHILD so we will not drop down in into this chunk: psig = tsk->parent->sighand; spin_lock_irqsave(&psig->siglock, flags); if (!tsk->ptrace && sig == SIGCHLD && (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { do_notify_parent will return false and so autoreap in exit_notify will be false. > > Baring any additional confusion on my part that cleanly solves the > problem of how not to send a signal from a child process cleanly. > > My apologies for sending you on a wild goose chase. > It's no problem. I learned a lot about signal handling :) _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
WARNING: multiple messages have this Message-ID (diff)
From: Mike Christie <michael.christie@oracle.com> To: "Eric W. Biederman" <ebiederm@xmission.com> Cc: geert@linux-m68k.org, vverma@digitalocean.com, hdanton@sina.com, hch@infradead.org, stefanha@redhat.com, jasowang@redhat.com, mst@redhat.com, sgarzare@redhat.com, virtualization@lists.linux-foundation.org, christian.brauner@ubuntu.com, axboe@kernel.dk, linux-kernel@vger.kernel.org Subject: Re: [PATCH V6 01/10] Use copy_process in vhost layer Date: Tue, 18 Jan 2022 12:51:27 -0600 [thread overview] Message-ID: <68ba89ae-108e-c14a-02a0-db72b169c9b1@oracle.com> (raw) In-Reply-To: <874k62b76d.fsf@email.froward.int.ebiederm.org> On 1/17/22 11:31 AM, Eric W. Biederman wrote: > Mike Christie <michael.christie@oracle.com> writes: > >> On 12/22/21 12:24 PM, Eric W. Biederman wrote: >>> All I am certain of is that you need to set >>> "args->exit_signal = -1;". This prevents having to play games with >>> do_notify_parent. >> >> Hi Eric, >> >> I have all your review comments handled except this one. It's looking like it's >> more difficult than just setting the exit_signal=-1, so I wanted to check that >> I understood you. > > [snip problems with exit_signal = -1] > >> >> What do you think? > > I was wrong. I appear to have confused the thread and the non-thread > cases. > > Perhaps I meant "args->exit_signal = 0". That looks like > do_notify_parent won't send it, and thread_group_leader continues to do > the right thing. That doesn't work too. exit_notify will call do_notify_parent but our parent, qemu, does not ignore SIGCHILD so we will not drop down in into this chunk: psig = tsk->parent->sighand; spin_lock_irqsave(&psig->siglock, flags); if (!tsk->ptrace && sig == SIGCHLD && (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { do_notify_parent will return false and so autoreap in exit_notify will be false. > > Baring any additional confusion on my part that cleanly solves the > problem of how not to send a signal from a child process cleanly. > > My apologies for sending you on a wild goose chase. > It's no problem. I learned a lot about signal handling :)
next prev parent reply other threads:[~2022-01-18 18:51 UTC|newest] Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-29 19:46 [PATCH V6 01/10] Use copy_process in vhost layer Mike Christie 2021-11-29 19:46 ` Mike Christie 2021-11-29 19:46 ` [PATCH V6 01/10] fork: Make IO worker options flag based Mike Christie 2021-11-29 19:46 ` Mike Christie 2021-11-29 19:46 ` [PATCH V6 02/10] fork/vm: Move common PF_IO_WORKER behavior to new flag Mike Christie 2021-11-29 19:46 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 03/10] fork: add USER_WORKER flag to not dup/clone files Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 04/10] fork: Add USER_WORKER flag to ignore signals Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 05/10] signal: Perfom autoreap for PF_USER_WORKER Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-12-17 18:42 ` Eric W. Biederman 2021-12-17 18:42 ` Eric W. Biederman 2021-11-29 19:47 ` [PATCH V6 06/10] fork: add helpers to clone a process for kernel use Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-12-17 18:53 ` Eric W. Biederman 2021-12-17 18:53 ` Eric W. Biederman 2021-11-29 19:47 ` [PATCH V6 07/10] io_uring: switch to user_worker Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 08/10] fork: remove create_io_thread Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 09/10] vhost: move worker thread fields to new struct Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-11-29 19:47 ` [PATCH V6 10/10] vhost: use user_worker to check RLIMITs Mike Christie 2021-11-29 19:47 ` Mike Christie 2021-12-17 19:01 ` Eric W. Biederman 2021-12-17 19:01 ` Eric W. Biederman 2021-12-08 20:34 ` [PATCH V6 01/10] Use copy_process in vhost layer Michael S. Tsirkin 2021-12-08 20:34 ` Michael S. Tsirkin 2021-12-08 22:13 ` michael.christie 2021-12-08 22:13 ` michael.christie 2021-12-09 9:32 ` Christian Brauner 2021-12-17 19:26 ` Eric W. Biederman 2021-12-17 19:26 ` Eric W. Biederman 2021-12-17 22:08 ` michael.christie 2021-12-17 22:08 ` michael.christie 2021-12-22 0:20 ` Eric W. Biederman 2021-12-22 0:20 ` Eric W. Biederman 2021-12-22 17:32 ` Mike Christie 2021-12-22 17:32 ` Mike Christie 2021-12-22 18:24 ` Eric W. Biederman 2021-12-22 18:24 ` Eric W. Biederman 2021-12-22 20:25 ` Michael S. Tsirkin 2021-12-22 20:25 ` Michael S. Tsirkin 2022-01-17 16:41 ` Mike Christie 2022-01-17 16:41 ` Mike Christie 2022-01-17 17:31 ` Eric W. Biederman 2022-01-17 17:31 ` Eric W. Biederman 2022-01-18 18:51 ` Mike Christie [this message] 2022-01-18 18:51 ` Mike Christie 2022-01-18 19:00 ` Mike Christie 2022-01-18 19:00 ` Mike Christie 2022-01-18 19:12 ` Eric W. Biederman 2022-01-18 19:12 ` Eric W. Biederman 2022-02-02 21:02 ` Mike Christie 2022-02-02 21:02 ` Mike Christie
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