14 Jan, 2009

1 commit


25 Jul, 2008

4 commits

  • This patch adds test that ensure the boundary conditions for the various
    constants introduced in the previous patches is met. No code is generated.

    [akpm@linux-foundation.org: fix alpha]
    Signed-off-by: Ulrich Drepper
    Acked-by: Davide Libenzi
    Cc: Michael Kerrisk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ulrich Drepper
     
  • This patch adds support for the SFD_NONBLOCK flag to signalfd4. The
    additional changes needed are minimal.

    The following test must be adjusted for architectures other than x86 and
    x86-64 and in case the syscall numbers changed.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    #include
    #include
    #include
    #include
    #include

    #ifndef __NR_signalfd4
    # ifdef __x86_64__
    # define __NR_signalfd4 289
    # elif defined __i386__
    # define __NR_signalfd4 327
    # else
    # error "need __NR_signalfd4"
    # endif
    #endif

    #define SFD_NONBLOCK O_NONBLOCK

    int
    main (void)
    {
    sigset_t ss;
    sigemptyset (&ss);
    sigaddset (&ss, SIGUSR1);
    int fd = syscall (__NR_signalfd4, -1, &ss, 8, 0);
    if (fd == -1)
    {
    puts ("signalfd4(0) failed");
    return 1;
    }
    int fl = fcntl (fd, F_GETFL);
    if (fl == -1)
    {
    puts ("fcntl failed");
    return 1;
    }
    if (fl & O_NONBLOCK)
    {
    puts ("signalfd4(0) set non-blocking mode");
    return 1;
    }
    close (fd);

    fd = syscall (__NR_signalfd4, -1, &ss, 8, SFD_NONBLOCK);
    if (fd == -1)
    {
    puts ("signalfd4(SFD_NONBLOCK) failed");
    return 1;
    }
    fl = fcntl (fd, F_GETFL);
    if (fl == -1)
    {
    puts ("fcntl failed");
    return 1;
    }
    if ((fl & O_NONBLOCK) == 0)
    {
    puts ("signalfd4(SFD_NONBLOCK) does not set non-blocking mode");
    return 1;
    }
    close (fd);

    puts ("OK");

    return 0;
    }
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Signed-off-by: Ulrich Drepper
    Acked-by: Davide Libenzi
    Cc: Michael Kerrisk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ulrich Drepper
     
  • This patch adds the new signalfd4 syscall. It extends the old signalfd
    syscall by one parameter which is meant to hold a flag value. In this
    patch the only flag support is SFD_CLOEXEC which causes the close-on-exec
    flag for the returned file descriptor to be set.

    A new name SFD_CLOEXEC is introduced which in this implementation must
    have the same value as O_CLOEXEC.

    The following test must be adjusted for architectures other than x86 and
    x86-64 and in case the syscall numbers changed.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    #include
    #include
    #include
    #include
    #include

    #ifndef __NR_signalfd4
    # ifdef __x86_64__
    # define __NR_signalfd4 289
    # elif defined __i386__
    # define __NR_signalfd4 327
    # else
    # error "need __NR_signalfd4"
    # endif
    #endif

    #define SFD_CLOEXEC O_CLOEXEC

    int
    main (void)
    {
    sigset_t ss;
    sigemptyset (&ss);
    sigaddset (&ss, SIGUSR1);
    int fd = syscall (__NR_signalfd4, -1, &ss, 8, 0);
    if (fd == -1)
    {
    puts ("signalfd4(0) failed");
    return 1;
    }
    int coe = fcntl (fd, F_GETFD);
    if (coe == -1)
    {
    puts ("fcntl failed");
    return 1;
    }
    if (coe & FD_CLOEXEC)
    {
    puts ("signalfd4(0) set close-on-exec flag");
    return 1;
    }
    close (fd);

    fd = syscall (__NR_signalfd4, -1, &ss, 8, SFD_CLOEXEC);
    if (fd == -1)
    {
    puts ("signalfd4(SFD_CLOEXEC) failed");
    return 1;
    }
    coe = fcntl (fd, F_GETFD);
    if (coe == -1)
    {
    puts ("fcntl failed");
    return 1;
    }
    if ((coe & FD_CLOEXEC) == 0)
    {
    puts ("signalfd4(SFD_CLOEXEC) does not set close-on-exec flag");
    return 1;
    }
    close (fd);

    puts ("OK");

    return 0;
    }
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [akpm@linux-foundation.org: add sys_ni stub]
    Signed-off-by: Ulrich Drepper
    Acked-by: Davide Libenzi
    Cc: Michael Kerrisk
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ulrich Drepper
     
  • This patch just extends the anon_inode_getfd interface to take an additional
    parameter with a flag value. The flag value is passed on to
    get_unused_fd_flags in anticipation for a use with the O_CLOEXEC flag.

    No actual semantic changes here, the changed callers all pass 0 for now.

    [akpm@linux-foundation.org: KVM fix]
    Signed-off-by: Ulrich Drepper
    Acked-by: Davide Libenzi
    Cc: Michael Kerrisk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ulrich Drepper
     

02 May, 2008

1 commit

  • a) none of the callers even looks at inode or file returned by anon_inode_getfd()
    b) any caller that would try to look at those would be racy, since by the time
    it returns we might have raced with close() from another thread and that
    file would be pining for fjords.

    Signed-off-by: Al Viro

    Al Viro
     

11 Apr, 2008

1 commit

  • Michael Kerrisk found out that signalfd was not reporting back user data
    pushed using sigqueue:

    http://groups.google.com/group/linux.kernel/msg/9397cab8551e3123

    The following patch makes signalfd report back the ssi_ptr and ssi_int members
    of the signalfd_siginfo structure.

    Signed-off-by: Davide Libenzi
    Acked-by: Michael Kerrisk
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Davide Libenzi
     

07 Feb, 2008

1 commit


03 Feb, 2008

1 commit


17 Oct, 2007

1 commit

  • For Michael Kerrisk request, the following patch renames signalfd_siginfo
    fields in order to keep them consistent with the siginfo_t ones.

    Signed-off-by: Davide Libenzi
    Cc: Michael Kerrisk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Davide Libenzi
     

21 Sep, 2007

1 commit

  • This simplifies signalfd code, by avoiding it to remain attached to the
    sighand during its lifetime.

    In this way, the signalfd remain attached to the sighand only during
    poll(2) (and select and epoll) and read(2). This also allows to remove
    all the custom "tsk == current" checks in kernel/signal.c, since
    dequeue_signal() will only be called by "current".

    I think this is also what Ben was suggesting time ago.

    The external effect of this, is that a thread can extract only its own
    private signals and the group ones. I think this is an acceptable
    behaviour, in that those are the signals the thread would be able to
    fetch w/out signalfd.

    Signed-off-by: Davide Libenzi
    Signed-off-by: Linus Torvalds

    Davide Libenzi
     

23 Aug, 2007

1 commit

  • With this patch any thread can dequeue its own private signals via signalfd,
    even if it was created by another sub-thread.

    To do so, we pass "current" to dequeue_signal() if the caller is from the same
    thread group. This also fixes the scheduling of posix timers broken by the
    previous patch.

    If the caller doesn't belong to this thread group, we can't handle __SI_TIMER
    case properly anyway. Perhaps we should forbid the cross-process signalfd usage
    and convert ctx->tsk to ctx->sighand.

    Signed-off-by: Oleg Nesterov
    Cc: Benjamin Herrenschmidt
    Cc: Davide Libenzi
    Cc: Ingo Molnar
    Cc: Michael Kerrisk
    Cc: Roland McGrath
    Cc: Thomas Gleixner
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

27 Jul, 2007

1 commit

  • This is probably a leftover from a time when the return wasn't there yet.
    Now the extra assignment is just irritating.

    Signed-off-by: Ulrich Drepper
    Cc: Davide Libenzi
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ulrich Drepper
     

29 Jun, 2007

1 commit

  • The new code in kernel/signal.c does not allow fetching private signals
    from another task. This patch avoid spurious POLLIN returns from a
    signalfd poll(2) operation.

    Signed-off-by: Davide Libenzi
    Cc: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Davide Libenzi
     

24 May, 2007

1 commit

  • Gathering signals in bulk enables server applications to drain a signal
    queue (almost full of realtime signals) more efficiently by reducing the
    syscall and file look-up overhead.

    Very similar to the sigtimedwait4() call described by Niels Provos, Chuck
    Lever, and Stephen Tweedie in a paper entitled "Analyzing the Overload
    Behavior of a Simple Web Server". The paper lists more details and
    advantages.

    Signed-off-by: Davi E. M. Arnaut
    Acked-by: Davide Libenzi
    Cc: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Davi Arnaut
     

11 May, 2007

1 commit

  • This patch series implements the new signalfd() system call.

    I took part of the original Linus code (and you know how badly it can be
    broken :), and I added even more breakage ;) Signals are fetched from the same
    signal queue used by the process, so signalfd will compete with standard
    kernel delivery in dequeue_signal(). If you want to reliably fetch signals on
    the signalfd file, you need to block them with sigprocmask(SIG_BLOCK). This
    seems to be working fine on my Dual Opteron machine. I made a quick test
    program for it:

    http://www.xmailserver.org/signafd-test.c

    The signalfd() system call implements signal delivery into a file descriptor
    receiver. The signalfd file descriptor if created with the following API:

    int signalfd(int ufd, const sigset_t *mask, size_t masksize);

    The "ufd" parameter allows to change an existing signalfd sigmask, w/out going
    to close/create cycle (Linus idea). Use "ufd" == -1 if you want a brand new
    signalfd file.

    The "mask" allows to specify the signal mask of signals that we are interested
    in. The "masksize" parameter is the size of "mask".

    The signalfd fd supports the poll(2) and read(2) system calls. The poll(2)
    will return POLLIN when signals are available to be dequeued. As a direct
    consequence of supporting the Linux poll subsystem, the signalfd fd can use
    used together with epoll(2) too.

    The read(2) system call will return a "struct signalfd_siginfo" structure in
    the userspace supplied buffer. The return value is the number of bytes copied
    in the supplied buffer, or -1 in case of error. The read(2) call can also
    return 0, in case the sighand structure to which the signalfd was attached,
    has been orphaned. The O_NONBLOCK flag is also supported, and read(2) will
    return -EAGAIN in case no signal is available.

    If the size of the buffer passed to read(2) is lower than sizeof(struct
    signalfd_siginfo), -EINVAL is returned. A read from the signalfd can also
    return -ERESTARTSYS in case a signal hits the process. The format of the
    struct signalfd_siginfo is, and the valid fields depends of the (->code &
    __SI_MASK) value, in the same way a struct siginfo would:

    struct signalfd_siginfo {
    __u32 signo; /* si_signo */
    __s32 err; /* si_errno */
    __s32 code; /* si_code */
    __u32 pid; /* si_pid */
    __u32 uid; /* si_uid */
    __s32 fd; /* si_fd */
    __u32 tid; /* si_fd */
    __u32 band; /* si_band */
    __u32 overrun; /* si_overrun */
    __u32 trapno; /* si_trapno */
    __s32 status; /* si_status */
    __s32 svint; /* si_int */
    __u64 svptr; /* si_ptr */
    __u64 utime; /* si_utime */
    __u64 stime; /* si_stime */
    __u64 addr; /* si_addr */
    };

    [akpm@linux-foundation.org: fix signalfd_copyinfo() on i386]
    Signed-off-by: Davide Libenzi
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Davide Libenzi