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SubjectRe: [PATCH v3] kernel/signal: Signal-based pre-coredump notification
On 10/23, Enke Chen wrote:
>
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -590,6 +590,12 @@ void do_coredump(const kernel_siginfo_t *siginfo)
> if (retval < 0)
> goto fail_creds;
>
> + /*
> + * Send the pre-coredump signal to the parent if requested.
> + */
> + do_notify_parent_predump();
> + cond_resched();

I am still not sure cond_resched() makes any sense here...

> @@ -1553,6 +1553,9 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
> tty_audit_fork(sig);
> sched_autogroup_fork(sig);
>
> + /* Clear the pre-coredump signal for the child */
> + sig->predump_signal = 0;

No need, copy_signal() does zalloc().


> +void do_notify_parent_predump(void)
> +{
> + struct sighand_struct *sighand;
> + struct kernel_siginfo info;
> + struct task_struct *parent;
> + unsigned long flags;
> + int sig;
> +
> + read_lock(&tasklist_lock);
> + parent = current->parent;
> + sig = parent->signal->predump_signal;
> + if (sig != 0) {
> + clear_siginfo(&info);
> + info.si_pid = task_tgid_vnr(current);
> + info.si_signo = sig;
> + if (sig == SIGCHLD)
> + info.si_code = CLD_PREDUMP;
> +
> + sighand = parent->sighand;
> + spin_lock_irqsave(&sighand->siglock, flags);
> + __group_send_sig_info(sig, &info, parent);
> + spin_unlock_irqrestore(&sighand->siglock, flags);

You can just use do_send_sig_info() and remove sighand/flags/spin_lock_irqsave.

Perhaps the "likely" predump_signal==0 check at the start makes sense to avoid
read_lock(tasklist).

And I'd suggest to move it into coredump.c and make it static. It won't have
another user.

Oleg.

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