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    SubjectRe: [PATCH] signalfd: fill in ssi_int for posix timers and message queues
    On Mon, 5 Jul 2010, Nathan Lynch wrote:

    > Hello Davide,
    >
    > On Sat, 2010-07-03 at 12:09 -0700, Davide Libenzi wrote:
    > > On Fri, 2 Jul 2010, Nathan Lynch wrote:
    > >
    > > > If signalfd is used to consume a signal generated by a POSIX interval
    > > > timer or POSIX message queue, the ssi_int field does not reflect the
    > > > data (sigevent->sigev_value) supplied to timer_create(2) or
    > > > mq_notify(3). (The ssi_ptr field, however, is filled in.)
    > > >
    > > > This behavior differs from signalfd's treatment of sigqueue-generated
    > > > signals -- see the default case in signalfd_copyinfo. It also gives
    > > > results that differ from the case when a signal is handled
    > > > conventionally via a sigaction-registered handler.
    > > >
    > > > So, set signalfd_siginfo->ssi_int in the remaining cases (__SI_TIMER,
    > > > __SI_MESGQ) where ssi_ptr is set.
    > > >
    > > > Signed-off-by: Nathan Lynch <ntl@pobox.com>
    > > > ---
    > > > fs/signalfd.c | 2 ++
    > > > 1 files changed, 2 insertions(+), 0 deletions(-)
    > > >
    > > > diff --git a/fs/signalfd.c b/fs/signalfd.c
    > > > index f329849..1c5a6ad 100644
    > > > --- a/fs/signalfd.c
    > > > +++ b/fs/signalfd.c
    > > > @@ -88,6 +88,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
    > > > err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
    > > > err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
    > > > err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
    > > > + err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
    > > > break;
    > > > case __SI_POLL:
    > > > err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
    > > > @@ -111,6 +112,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
    > > > err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
    > > > err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
    > > > err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
    > > > + err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
    > > > break;
    > > > default:
    > >
    > > I am fine with it, but I now noticed that signalfd_copyinfo() got out of
    > > sync from copy_siginfo_to_user(), which should match.
    > > Do you mind aligning that too, as part of your patch?
    > > An adding a comment on the lines of the one in copy_siginfo_to_user() to
    > > signalfd_copyinfo() too?
    >
    > Sorry, I'm not sure I understand. Are you saying that
    > copy_siginfo_to_user should have analogous lines added to assign to
    > si_int? That's actually not necessary if I read the code correctly: in
    > struct siginfo, si_ptr and si_int are members of a sigval union, so
    > assigning to the former covers the latter. signalfd must assign both
    > ssi_ptr and ssi_int since they occupy different locations in
    > signalfd_siginfo.
    >
    > Perhaps the attached testcases make the problem (as I see it) more
    > clear? The final assertion fails without this patch.

    Sorry, my bad. I had forgotten that siginfo had them in a union, so the
    different code in signalfd_copyinfo() is needed.
    Patch looks fine to me as is.


    - Davide




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