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Re: [PATCH v3 2/3] Consolidate Linux sigprocmask implementation (BZ #22391)
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Tue, 12 Dec 2017 15:03:27 -0200
- Subject: Re: [PATCH v3 2/3] Consolidate Linux sigprocmask implementation (BZ #22391)
- Authentication-results: sourceware.org; auth=none
- References: <1510768451-18453-1-git-send-email-adhemerval.zanella@linaro.org> <1510768451-18453-2-git-send-email-adhemerval.zanella@linaro.org>
Ping (with Rical suggested changes).
On 15/11/2017 15:54, Adhemerval Zanella wrote:
> Changes from previous version:
>
> - Cleanup __nptl prefix from the generic names.
>
> ---
>
> This patch consolidates the sigprocmask Linux syscall implementation on
> sysdeps/unix/sysv/linux/sigprocmask.c. The changes are:
>
> 1. For ia64, s390-64, sparc64, and x86_64 the default semantic for
> filter out SIGCANCEL and SIGSETXID is used. Also the Linux pthread
> semantic is documented in the signal chapter.
>
> 2. A new internal function to check for NPTL internal signals within a
> signal set is added (__has_internal_signal). It is used to
> simplify the default sigprocmask.c implementation.
>
> Checked on x86_64-linux-gnu.
>
> [BZ #22391]
> * manual/signal.texi: Add a note about internal pthread signals
> on Linux.
> * sysdeps/unix/sysv/linux/alpha/sigprocmask.c: Remove file.
> * sysdeps/unix/sysv/linux/ia64/sigprocmask.c: Likewise.
> * sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c: Likewise.
> * sysdeps/unix/sysv/linux/sparc/sparc64/sigprocmask.c: Likewise.
> * sysdeps/unix/sysv/linux/x86_64/sigprocmask.c: Likewise.
> * sysdeps/unix/sysv/linux/internal-signals.h
> (__has_internal_signal): New function.
> * sysdeps/unix/sysv/linux/sigprocmask.c (__sigprocmask):
> Use __has_internal_signal and __clear_internal_signals
> function.
>
> Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> Signed-off-by: Zack Weinberg <zackw@panix.com>
> Reported-by: Yury Norov <ynorov@caviumnetworks.com>
> ---
> ChangeLog | 17 +++++++
> manual/signal.texi | 37 ++++++++++++++
> sysdeps/unix/sysv/linux/alpha/sigprocmask.c | 58 ----------------------
> sysdeps/unix/sysv/linux/ia64/sigprocmask.c | 40 ---------------
> sysdeps/unix/sysv/linux/internal-signals.h | 6 +++
> sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c | 38 --------------
> sysdeps/unix/sysv/linux/sigprocmask.c | 23 +++------
> .../unix/sysv/linux/sparc/sparc64/sigprocmask.c | 34 -------------
> sysdeps/unix/sysv/linux/x86_64/sigprocmask.c | 39 ---------------
> 9 files changed, 66 insertions(+), 226 deletions(-)
> delete mode 100644 sysdeps/unix/sysv/linux/alpha/sigprocmask.c
> delete mode 100644 sysdeps/unix/sysv/linux/ia64/sigprocmask.c
> delete mode 100644 sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c
> delete mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/sigprocmask.c
> delete mode 100644 sysdeps/unix/sysv/linux/x86_64/sigprocmask.c
>
> diff --git a/manual/signal.texi b/manual/signal.texi
> index 9577ff0..4f0ef59 100644
> --- a/manual/signal.texi
> +++ b/manual/signal.texi
> @@ -235,6 +235,7 @@ defined. Since the signal numbers are allocated consecutively,
> * Job Control Signals:: Signals used to support job control.
> * Operation Error Signals:: Used to report operational system errors.
> * Miscellaneous Signals:: Miscellaneous Signals.
> +* Internally-Used Signals:: Signals used internally by the C library.
> * Signal Messages:: Printing a message describing a signal.
> @end menu
>
> @@ -794,6 +795,26 @@ in @ref{Signaling Another Process}.
> The default action is to terminate the process.
> @end deftypevr
>
> +@deftypevr Macro int SIGRTMIN
> +@deftypevrx Macro int SIGRTMAX
> +@standards{POSIX.1, signal.h}
> +@cindex real-time signals
> +The range of signal numbers @code{SIGRTMIN}, @code{SIGRTMIN+1},
> +@dots{}, @code{SIGRTMAX} is also set aside for you to use any way you
> +want. In addition, these signals (and no others) are guaranteed to
> +support @dfn{real-time} signal semantics, which unfortunately this
> +manual does not yet document.
> +
> +Unlike all of the other signal number macros, @code{SIGRTMIN} and
> +@code{SIGRTMAX} are not compile-time constants, because some operating
> +systems make the number of real-time signals tunable on a
> +per-installation or even per-process basis. However, POSIX guarantees
> +that there will be at least 8 signal numbers in this range.
> +
> +The default action for all signals in this range is to terminate the
> +process.
> +@end deftypevr
> +
> @deftypevr Macro int SIGWINCH
> @standards{BSD, signal.h}
> Window size change. This is generated on some systems (including GNU)
> @@ -817,6 +838,22 @@ to print some status information about the system and what the process
> is doing. Otherwise the default is to do nothing.
> @end deftypevr
>
> +@node Internally-Used Signals
> +@subsection Internally-Used Signals
> +@cindex internally used signals
> +
> +On some operating systems, @theglibc{} needs to use a few signals from
> +the ``true'' real-time range internally, to implement thread
> +cancellation, cross-thread effective ID synchronization, POSIX timer
> +management, etc. @Theglibc{} adjusts @code{SIGRTMIN} and
> +@code{SIGRTMAX} to exclude these signals, and it also takes steps to
> +prevent application code from altering their state: @code{sigprocmask}
> +cannot block them and @code{sigaction} cannot redefine their handlers,
> +for instance. Therefore, most programs do not need to know or care
> +about these signals. We mainly document their existence for the sake
> +of anyone who has ever wondered why there is a gap between the
> +highest-numbered ``normal'' signal and @code{SIGRTMIN} on Linux.
> +
> @node Signal Messages
> @subsection Signal Messages
> @cindex signal messages
> diff --git a/sysdeps/unix/sysv/linux/alpha/sigprocmask.c b/sysdeps/unix/sysv/linux/alpha/sigprocmask.c
> deleted file mode 100644
> index ebec70c..0000000
> --- a/sysdeps/unix/sysv/linux/alpha/sigprocmask.c
> +++ /dev/null
> @@ -1,58 +0,0 @@
> -/* Copyright (C) 1993-2017 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> - Contributed by David Mosberger (davidm@azstarnet.com).
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library. If not, see
> - <http://www.gnu.org/licenses/>. */
> -
> -#include <errno.h>
> -#include <sysdep.h>
> -#include <signal.h>
> -
> -/* When there is kernel support for more than 64 signals, we'll have to
> - switch to a new system call convention here. */
> -
> -int
> -__sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> -{
> - unsigned long int setval;
> - long result;
> -
> - if (set)
> - setval = set->__val[0];
> - else
> - {
> - setval = 0;
> - how = SIG_BLOCK; /* ensure blocked mask doesn't get changed */
> - }
> -
> - result = INLINE_SYSCALL (osf_sigprocmask, 2, how, setval);
> - if (result == -1)
> - /* If there are ever more than 63 signals, we need to recode this
> - in assembler since we wouldn't be able to distinguish a mask of
> - all 1s from -1, but for now, we're doing just fine... */
> - return result;
> -
> - if (oset)
> - {
> - oset->__val[0] = result;
> - result = _SIGSET_NWORDS;
> - while (--result > 0)
> - oset->__val[result] = 0;
> - }
> - return 0;
> -}
> -
> -libc_hidden_def (__sigprocmask)
> -weak_alias (__sigprocmask, sigprocmask);
> diff --git a/sysdeps/unix/sysv/linux/ia64/sigprocmask.c b/sysdeps/unix/sysv/linux/ia64/sigprocmask.c
> deleted file mode 100644
> index 920c5fd..0000000
> --- a/sysdeps/unix/sysv/linux/ia64/sigprocmask.c
> +++ /dev/null
> @@ -1,40 +0,0 @@
> -/* Copyright (C) 1997-2017 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> - Linux/IA64 specific sigprocmask
> - Written by Jes Sorensen, <Jes.Sorensen@cern.ch>, April 1999.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <http://www.gnu.org/licenses/>. */
> -
> -/* Linux/ia64 only has rt signals, thus we do not even want to try falling
> - back to the old style signals as the default Linux handler does. */
> -
> -#include <errno.h>
> -#include <signal.h>
> -#include <unistd.h>
> -
> -#include <sysdep.h>
> -#include <sys/syscall.h>
> -
> -/* Get and/or change the set of blocked signals. */
> -int
> -__sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> -{
> -
> - /* XXX The size argument hopefully will have to be changed to the
> - real size of the user-level sigset_t. */
> - return INLINE_SYSCALL (rt_sigprocmask, 4, how, set, oset, _NSIG / 8);
> -}
> -libc_hidden_def (__sigprocmask)
> -weak_alias (__sigprocmask, sigprocmask)
> diff --git a/sysdeps/unix/sysv/linux/internal-signals.h b/sysdeps/unix/sysv/linux/internal-signals.h
> index e96a718..bb8234d 100644
> --- a/sysdeps/unix/sysv/linux/internal-signals.h
> +++ b/sysdeps/unix/sysv/linux/internal-signals.h
> @@ -36,6 +36,12 @@
> #define SIGSETXID (__SIGRTMIN + 1)
>
>
> +static inline bool
> +__has_internal_signal (const sigset_t *set)
> +{
> + return __sigismember (set, SIGCANCEL) || __sigismember (set, SIGSETXID);
> +}
> +
> /* Return is sig is used internally. */
> static inline int
> __is_internal_signal (int sig)
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c b/sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c
> deleted file mode 100644
> index a8010e7..0000000
> --- a/sysdeps/unix/sysv/linux/s390/s390-64/sigprocmask.c
> +++ /dev/null
> @@ -1,38 +0,0 @@
> -/* Copyright (C) 2001-2017 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <http://www.gnu.org/licenses/>. */
> -
> -/* 64 bit Linux for S/390 only has rt signals, thus we do not even want to try
> - falling back to the old style signals as the default Linux handler does. */
> -
> -#include <errno.h>
> -#include <signal.h>
> -#include <unistd.h>
> -
> -#include <sysdep.h>
> -#include <sys/syscall.h>
> -
> -/* Get and/or change the set of blocked signals. */
> -int
> -__sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> -{
> -
> - /* XXX The size argument hopefully will have to be changed to the
> - real size of the user-level sigset_t. */
> - return INLINE_SYSCALL (rt_sigprocmask, 4, how, set, oset, _NSIG / 8);
> -}
> -libc_hidden_def (__sigprocmask)
> -weak_alias (__sigprocmask, sigprocmask)
> diff --git a/sysdeps/unix/sysv/linux/sigprocmask.c b/sysdeps/unix/sysv/linux/sigprocmask.c
> index e776563..e574b5d 100644
> --- a/sysdeps/unix/sysv/linux/sigprocmask.c
> +++ b/sysdeps/unix/sysv/linux/sigprocmask.c
> @@ -1,4 +1,5 @@
> -/* Copyright (C) 1997-2017 Free Software Foundation, Inc.
> +/* Get and/or change the set of blocked signals. Linux version.
> + Copyright (C) 1997-2017 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -17,34 +18,22 @@
>
> #include <errno.h>
> #include <signal.h>
> -#include <string.h> /* Needed for string function builtin redirection. */
> -#include <unistd.h>
> +#include <internal-signals.h>
>
> -#include <sysdep.h>
> -#include <sys/syscall.h>
>
> -#include <nptl/pthreadP.h> /* SIGCANCEL, SIGSETXID */
> -
> -
> -/* Get and/or change the set of blocked signals. */
> int
> __sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> {
> sigset_t local_newmask;
>
> - /* The only thing we have to make sure here is that SIGCANCEL and
> - SIGSETXID are not blocked. */
> - if (set != NULL
> - && (__builtin_expect (__sigismember (set, SIGCANCEL), 0)
> - || __builtin_expect (__sigismember (set, SIGSETXID), 0)))
> + if (set != NULL && __glibc_unlikely (__has_internal_signal (set)))
> {
> local_newmask = *set;
> - __sigdelset (&local_newmask, SIGCANCEL);
> - __sigdelset (&local_newmask, SIGSETXID);
> + __clear_internal_signals (&local_newmask);
> set = &local_newmask;
> }
>
> - return INLINE_SYSCALL (rt_sigprocmask, 4, how, set, oset, _NSIG / 8);
> + return INLINE_SYSCALL_CALL (rt_sigprocmask, how, set, oset, _NSIG / 8);
> }
> libc_hidden_def (__sigprocmask)
> weak_alias (__sigprocmask, sigprocmask)
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/sigprocmask.c b/sysdeps/unix/sysv/linux/sparc/sparc64/sigprocmask.c
> deleted file mode 100644
> index ef7d7fe..0000000
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/sigprocmask.c
> +++ /dev/null
> @@ -1,34 +0,0 @@
> -/* Copyright (C) 1997-2017 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <http://www.gnu.org/licenses/>. */
> -
> -#include <errno.h>
> -#include <signal.h>
> -#include <unistd.h>
> -
> -#include <sysdep.h>
> -#include <sys/syscall.h>
> -
> -/* Get and/or change the set of blocked signals. */
> -int
> -__sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> -{
> - /* XXX The size argument hopefully will have to be changed to the
> - real size of the user-level sigset_t. */
> - return INLINE_SYSCALL (rt_sigprocmask, 4, how, set, oset, _NSIG / 8);
> -}
> -libc_hidden_def (__sigprocmask)
> -weak_alias (__sigprocmask, sigprocmask)
> diff --git a/sysdeps/unix/sysv/linux/x86_64/sigprocmask.c b/sysdeps/unix/sysv/linux/x86_64/sigprocmask.c
> deleted file mode 100644
> index 1610ddf..0000000
> --- a/sysdeps/unix/sysv/linux/x86_64/sigprocmask.c
> +++ /dev/null
> @@ -1,39 +0,0 @@
> -/* Copyright (C) 1997-2017 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> - Written by Jes Sorensen, <Jes.Sorensen@cern.ch>, April 1999.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <http://www.gnu.org/licenses/>. */
> -
> -/* Linux/x86_64 only has rt signals, thus we do not even want to try falling
> - back to the old style signals as the default Linux handler does. */
> -
> -#include <errno.h>
> -#include <signal.h>
> -#include <unistd.h>
> -
> -#include <sysdep.h>
> -#include <sys/syscall.h>
> -
> -/* Get and/or change the set of blocked signals. */
> -int
> -__sigprocmask (int how, const sigset_t *set, sigset_t *oset)
> -{
> -
> - /* XXX The size argument hopefully will have to be changed to the
> - real size of the user-level sigset_t. */
> - return INLINE_SYSCALL (rt_sigprocmask, 4, how, set, oset, _NSIG / 8);
> -}
> -libc_hidden_def (__sigprocmask)
> -weak_alias (__sigprocmask, sigprocmask)
>