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    SubjectRe: [PATCH 2/7] io_uring: handle signals for IO threads like a normal thread
    Jens Axboe <axboe@kernel.dk> writes:

    > We go through various hoops to disallow signals for the IO threads, but
    > there's really no reason why we cannot just allow them. The IO threads
    > never return to userspace like a normal thread, and hence don't go through
    > normal signal processing. Instead, just check for a pending signal as part
    > of the work loop, and call get_signal() to handle it for us if anything
    > is pending.
    >
    > With that, we can support receiving signals, including special ones like
    > SIGSTOP.
    >
    > Signed-off-by: Jens Axboe <axboe@kernel.dk>
    > ---
    > fs/io-wq.c | 24 +++++++++++++++++-------
    > fs/io_uring.c | 12 ++++++++----
    > 2 files changed, 25 insertions(+), 11 deletions(-)
    >
    > diff --git a/fs/io-wq.c b/fs/io-wq.c
    > index b7c1fa932cb3..3e2f059a1737 100644
    > --- a/fs/io-wq.c
    > +++ b/fs/io-wq.c
    > @@ -16,7 +16,6 @@
    > #include <linux/rculist_nulls.h>
    > #include <linux/cpu.h>
    > #include <linux/tracehook.h>
    > -#include <linux/freezer.h>
    >
    > #include "../kernel/sched/sched.h"
    > #include "io-wq.h"
    > @@ -503,10 +502,16 @@ static int io_wqe_worker(void *data)
    > if (io_flush_signals())
    > continue;
    > ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
    > - if (try_to_freeze() || ret)
    > + if (signal_pending(current)) {
    > + struct ksignal ksig;
    > +
    > + if (fatal_signal_pending(current))
    > + break;
    > + if (get_signal(&ksig))
    > + continue;
    ^^^^^^^^^^^^^^^^^^^^^^

    That is wrong. You are promising to deliver a signal to signal
    handler and them simply discarding it. Perhaps:

    if (!get_signal(&ksig))
    continue;
    WARN_ON(!sig_kernel_stop(ksig->sig));
    break;


    Eric

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