Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756839Ab0GEMWP (ORCPT ); Mon, 5 Jul 2010 08:22:15 -0400 Received: from a-pb-sasl-quonix.pobox.com ([208.72.237.25]:62826 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753790Ab0GEMWN (ORCPT ); Mon, 5 Jul 2010 08:22:13 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=subject:from:to :cc:in-reply-to:references:content-type:date:message-id :mime-version; q=dns; s=sasl; b=GkxNC566+2OkjbTQyYZnDCqfLECoRCjw P5EZC6ujv4GXeH10JrX+etz2bIBhS7g+a6XyyHrAQtBMo6MoU5HhjNm1N1Bch3EN 9C7u6Ow8QybYMwxqqSa+uMgpqZGDbjIxJRY4OrNt4kqyquKF0yohpxowYYoTq3iq rQR6eFq6Jgo= Subject: Re: [PATCH] signalfd: fill in ssi_int for posix timers and message queues From: Nathan Lynch To: Davide Libenzi Cc: Linux Kernel Mailing List In-Reply-To: References: <1278117528.21917.354.camel@localhost> Content-Type: multipart/mixed; boundary="=-aHqtwTCsqcB1lp/HZfus" Date: Mon, 05 Jul 2010 07:22:55 -0500 Message-ID: <1278332575.13403.24.camel@tp-r400> Mime-Version: 1.0 X-Mailer: Evolution 2.30.1.2 (2.30.1.2-8.fc13) X-Pobox-Relay-ID: EE289F2E-882F-11DF-9A5A-9056EE7EF46B-04752483!a-pb-sasl-quonix.pobox.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8361 Lines: 295 --=-aHqtwTCsqcB1lp/HZfus Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit 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 > > --- > > 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. --=-aHqtwTCsqcB1lp/HZfus Content-Disposition: attachment; filename="mq_notify-vs-signalfd.c" Content-Type: text/x-csrc; name="mq_notify-vs-signalfd.c"; charset="UTF-8" Content-Transfer-Encoding: 7bit #include #include #include #include #include #include #include #include #include static int handler_run; static const union sigval my_sigval = { .sival_int = 42, }; static const char msgbuf[] = "hello"; #define bail(msg) \ do { perror(msg); exit(EXIT_FAILURE); } while (0); static void handler(int sig, siginfo_t *si, void *notused) { assert(si->si_code == SI_MESGQ); assert(si->si_ptr == my_sigval.sival_ptr); /* Succeeds */ assert(si->si_int == my_sigval.sival_int); /* Succeeds */ /* This should run only once */ assert(handler_run == 0); handler_run++; } int main(int argc, char *argv[]) { struct signalfd_siginfo fdsi; struct sigaction newact; struct sigevent sev; struct mq_attr attr; sigset_t mask; size_t msglen; char *rcvbuf; mqd_t mqdes; ssize_t s; int sfd; if (argc != 2) { fprintf(stderr, "Usage: %s \n", argv[0]); exit(EXIT_FAILURE); } newact.sa_flags = SA_SIGINFO | SA_RESETHAND; newact.sa_sigaction = handler; sigemptyset(&newact.sa_mask); if (sigaction(SIGRTMIN, &newact, NULL) == -1) bail("sigaction"); mqdes = mq_unlink(argv[1]); if (mqdes == -1 && errno != ENOENT) bail("mq_unlink"); mqdes = mq_open(argv[1], (O_RDWR | O_CREAT), 0600, NULL); if (mqdes == (mqd_t) -1) bail("mq_open"); memset(&sev, 0, sizeof(sev)); sev.sigev_notify = SIGEV_SIGNAL; sev.sigev_signo = SIGRTMIN; sev.sigev_value = my_sigval; if (mq_notify(mqdes, &sev) == -1) bail("mq_notify"); if (mq_send(mqdes, msgbuf, sizeof(msgbuf), 0) == -1) bail("mq_send"); while (!handler_run) usleep(100000); if (mq_getattr(mqdes, &attr) == -1) bail("mq_getattr"); msglen = attr.mq_msgsize; rcvbuf = malloc(msglen); if (!rcvbuf) bail("malloc"); /* Empty the queue */ if (mq_receive(mqdes, rcvbuf, msglen, NULL) != sizeof(msgbuf)) bail("mq_receive"); /* Inhibit default SIGRTMIN handling */ sigemptyset(&mask); sigaddset(&mask, SIGRTMIN); if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1) bail("sigprocmask"); /* Reregister the notifier and post another message */ if (mq_notify(mqdes, &sev) == -1) bail("mq_notify"); if (mq_send(mqdes, msgbuf, sizeof(msgbuf), 0) == -1) bail("mq_send"); sfd = signalfd(-1, &mask, 0); if (sfd == -1) bail("signalfd"); /* Handle the signal */ s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo)); if (s != sizeof(struct signalfd_siginfo)) bail("read"); assert(fdsi.ssi_code == SI_MESGQ); assert(fdsi.ssi_ptr == (unsigned long)my_sigval.sival_ptr); /* Succeeds */ assert(fdsi.ssi_int == my_sigval.sival_int); /* Fails */ exit(EXIT_SUCCESS); } --=-aHqtwTCsqcB1lp/HZfus Content-Disposition: attachment; filename="timer-vs-signalfd.c" Content-Type: text/x-csrc; name="timer-vs-signalfd.c"; charset="UTF-8" Content-Transfer-Encoding: 7bit #include #include #include #include #include #include #include #include static int handler_run; static const union sigval my_sigval = { .sival_int = 42, }; #define bail(msg) \ do { perror(msg); exit(EXIT_FAILURE); } while (0); static void handler(int sig, siginfo_t *si, void *notused) { assert(si->si_code == SI_TIMER); assert(si->si_ptr == my_sigval.sival_ptr); /* Succeeds */ assert(si->si_int == my_sigval.sival_int); /* Succeeds */ /* This should run only once */ assert(handler_run == 0); handler_run++; } int main(void) { struct signalfd_siginfo fdsi; struct sigaction newact; struct itimerspec its; struct sigevent sev; timer_t timerid; sigset_t mask; ssize_t s; int sfd; newact.sa_flags = SA_SIGINFO | SA_RESETHAND; newact.sa_sigaction = handler; sigemptyset(&newact.sa_mask); if (sigaction(SIGRTMIN, &newact, NULL) == -1) bail("sigaction"); memset(&sev, 0, sizeof(sev)); sev.sigev_notify = SIGEV_SIGNAL; sev.sigev_signo = SIGRTMIN; sev.sigev_value = my_sigval; if (timer_create(CLOCK_REALTIME, &sev, &timerid) == -1) bail("timer_create"); /* Timer expires just once */ its.it_value.tv_sec = 0; its.it_value.tv_nsec = 100; its.it_interval.tv_sec = 0; its.it_interval.tv_nsec = 0; /* Arm timer */ if (timer_settime(timerid, 0, &its, NULL) == -1) bail("timer_settime"); /* Wait for timer to expire, which executes the handler */ while (!handler_run) usleep(100000); /* Inhibit default SIGRTMIN handling */ sigemptyset(&mask); sigaddset(&mask, SIGRTMIN); if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1) bail("sigprocmask"); sfd = signalfd(-1, &mask, 0); if (sfd == -1) bail("signalfd"); /* Re-arm timer */ if (timer_settime(timerid, 0, &its, NULL) == -1) bail("timer_settime"); /* Block until timer expiration */ s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo)); if (s != sizeof(struct signalfd_siginfo)) bail("read"); assert(fdsi.ssi_code == SI_TIMER); assert(fdsi.ssi_ptr == (unsigned long)my_sigval.sival_ptr); /* Succeeds */ assert(fdsi.ssi_int == my_sigval.sival_int); /* Fails */ return EXIT_SUCCESS; } --=-aHqtwTCsqcB1lp/HZfus-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/