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    SubjectRe: [PATCH 3/3] exec: Allow do_coredump to wait for user space pipe readers to complete (v7)
    On 07/02, Neil Horman wrote:
    >
    > +static void wait_for_dump_helpers(struct file *file)
    > +{
    > + struct pipe_inode_info *pipe;
    > +
    > + pipe = file->f_path.dentry->d_inode->i_pipe;
    > +
    > + pipe_lock(pipe);
    > + pipe->readers++;
    > + pipe->writers--;
    > +
    > + while ((pipe->readers > 1) && (!fatal_signal_pending(current))) {
    > + wake_up_interruptible_sync(&pipe->wait);
    > + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
    > + pipe_wait(pipe);
    > + }

    The kernel can hang on UP machine.

    Suppose that rt task starts the coredump and then recieves a non-fatal
    signal before core_pattern app closes stdin.

    In that case this "while()" above becomes a busy-wait loop which never
    stops.

    Neil, please use signal_pending() as I said. Yes, this means wait_for_
    will abort if we recieve a non-fatal signal. But as I said we have other
    problems with signals here, when we fix them wait_for_dump_helpers()
    will be fixed automatically.

    Oleg.



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