Reduce <limits.h> pollution due to dynamic PTHREAD_STACK_MIN
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dj/TryBot-apply_patch |
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Patch applied to master at the time it was sent
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dj/TryBot-32bit |
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Build for i686
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Commit Message
<limits.h> used to be a header file with no declarations.
GCC's libgomp includes in a #pragma GCC visibility hidden block.
Including <unistd.h> from <limits.h> (indirectly) declares everything
in <unistd.h> with hidden visibility, resulting in linker failures.
This commit avoids C declarations in assembler mode and only declares
__sysconf in <limits.h> (and not the entire contents of <unistd.h>).
The __sysconf symbol is already part of the ABI. PTHREAD_STACK_MIN
is no longer defined for __USE_DYNAMIC_STACK_SIZE && __ASSEMBLER__
because there is no possible definition.
Additionally, PTHREAD_STACK_MIN is now defined by <pthread.h> for
__USE_MISC because this is what developers expect based on the macro
name. It also helps to avoid libgomp linker failures in GCC because
libgomp includes <pthread.h> before its visibility hacks.
---
include/bits/local_lim.h | 7 -----
nptl/tst-minstack-exit.c | 3 +++
sysdeps/nptl/pthread.h | 4 ++-
sysdeps/unix/sysv/linux/Makefile | 2 +-
sysdeps/unix/sysv/linux/bits/local_lim.h | 10 ++-----
.../sysv/linux/bits/pthread_stack_min-dynamic.h | 31 ++++++++++++++++++++++
.../linux/include/bits/pthread_stack_min-dynamic.h | 7 +++++
7 files changed, 47 insertions(+), 17 deletions(-)
Comments
On 7/12/21 8:53 AM, Florian Weimer wrote:
> <limits.h> used to be a header file with no declarations.
> GCC's libgomp includes in a #pragma GCC visibility hidden block.
> Including <unistd.h> from <limits.h> (indirectly) declares everything
> in <unistd.h> with hidden visibility, resulting in linker failures.
>
> This commit avoids C declarations in assembler mode and only declares
> __sysconf in <limits.h> (and not the entire contents of <unistd.h>).
> The __sysconf symbol is already part of the ABI. PTHREAD_STACK_MIN
> is no longer defined for __USE_DYNAMIC_STACK_SIZE && __ASSEMBLER__
> because there is no possible definition.
>
> Additionally, PTHREAD_STACK_MIN is now defined by <pthread.h> for
> __USE_MISC because this is what developers expect based on the macro
> name. It also helps to avoid libgomp linker failures in GCC because
> libgomp includes <pthread.h> before its visibility hacks.
We absolutely want to be able to build glibc with an unmodified released
gcc, and requiring a fix would impact usability. Therefore regardless of
the exact technical merits of this fix, I think it goes in the right
direction. At a later date we can cleanup this technical debt.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
> ---
> include/bits/local_lim.h | 7 -----
> nptl/tst-minstack-exit.c | 3 +++
> sysdeps/nptl/pthread.h | 4 ++-
> sysdeps/unix/sysv/linux/Makefile | 2 +-
> sysdeps/unix/sysv/linux/bits/local_lim.h | 10 ++-----
> .../sysv/linux/bits/pthread_stack_min-dynamic.h | 31 ++++++++++++++++++++++
> .../linux/include/bits/pthread_stack_min-dynamic.h | 7 +++++
> 7 files changed, 47 insertions(+), 17 deletions(-)
>
> diff --git a/include/bits/local_lim.h b/include/bits/local_lim.h
> deleted file mode 100644
> index 46d82dc729..0000000000
> --- a/include/bits/local_lim.h
> +++ /dev/null
> @@ -1,7 +0,0 @@
> -/* Don't define PTHREAD_STACK_MIN to sysconf (_SC_THREAD_STACK_MIN) for
> - glibc build. */
> -#if !defined _ISOMAC
> -# undef __USE_DYNAMIC_STACK_SIZE
> -#endif
> -
> -#include_next <bits/local_lim.h>
OK. This moves from bits/local_lim.h -> sysdeps/unix/sysv/linux/include/bits/pthread_stack_min-dynamic.h
> diff --git a/nptl/tst-minstack-exit.c b/nptl/tst-minstack-exit.c
> index 4e7dc3e786..e577924178 100644
> --- a/nptl/tst-minstack-exit.c
> +++ b/nptl/tst-minstack-exit.c
> @@ -24,6 +24,9 @@
> #include <support/check.h>
> #include <support/xthread.h>
>
> +_Static_assert (__SC_THREAD_STACK_MIN_VALUE == _SC_THREAD_STACK_MIN,
> + "__SC_THREAD_STACK_MIN_VALUE is correct");
> +
OK. Keeps the constant value checked so it doesn't change.
> static void *
> threadfunc (void *closure)
> {
> diff --git a/sysdeps/nptl/pthread.h b/sysdeps/nptl/pthread.h
> index 52e2eadbfc..f1b7f2bdc6 100644
> --- a/sysdeps/nptl/pthread.h
> +++ b/sysdeps/nptl/pthread.h
> @@ -29,7 +29,9 @@
> #include <bits/types/struct_timespec.h>
> #include <bits/types/__sigset_t.h>
> #include <bits/types/struct___jmp_buf_tag.h>
> -
> +#ifdef __USE_MISC
> +# include <bits/pthread_stack_min-dynamic.h>
> +#endif
OK. Include it early (everyone using pthread.h would expect it).
>
> /* Detach state. */
> enum
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 7d43dc95f2..8257e5b548 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -109,7 +109,7 @@ sysdep_headers += sys/mount.h sys/acct.h \
> bits/types/struct_semid64_ds_helper.h \
> bits/types/struct_shmid64_ds.h \
> bits/types/struct_shmid64_ds_helper.h \
> - bits/pthread_stack_min.h
> + bits/pthread_stack_min.h bits/pthread_stack_min-dynamic.h
OK.
>
> tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
> tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
> diff --git a/sysdeps/unix/sysv/linux/bits/local_lim.h b/sysdeps/unix/sysv/linux/bits/local_lim.h
> index 0b1c7f40be..b8f89236bc 100644
> --- a/sysdeps/unix/sysv/linux/bits/local_lim.h
> +++ b/sysdeps/unix/sysv/linux/bits/local_lim.h
> @@ -77,14 +77,8 @@
> priority level. */
> #define AIO_PRIO_DELTA_MAX 20
>
> -/* Minimum size for a thread. We are free to choose a reasonable value. */
> -#undef PTHREAD_STACK_MIN
> -#if defined __USE_DYNAMIC_STACK_SIZE && __USE_DYNAMIC_STACK_SIZE
> -# include <unistd.h>
> -# define PTHREAD_STACK_MIN sysconf (_SC_THREAD_STACK_MIN)
> -#else
> -# include <bits/pthread_stack_min.h>
> -#endif
> +/* Arrange for the definition of PTHREAD_STACK_MIN. */
> +#include <bits/pthread_stack_min-dynamic.h>
OK.
>
> /* Maximum number of timer expiration overruns. */
> #define DELAYTIMER_MAX 2147483647
> diff --git a/sysdeps/unix/sysv/linux/bits/pthread_stack_min-dynamic.h b/sysdeps/unix/sysv/linux/bits/pthread_stack_min-dynamic.h
> new file mode 100644
> index 0000000000..5f5fc5f024
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/bits/pthread_stack_min-dynamic.h
> @@ -0,0 +1,31 @@
> +/* Definition of PTHREAD_STACK_MIN, possibly dynamic.
> + Copyright (C) 2021 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
> + <https://www.gnu.org/licenses/>. */
> +
> +#ifndef PTHREAD_STACK_MIN
> +# if defined __USE_DYNAMIC_STACK_SIZE && __USE_DYNAMIC_STACK_SIZE
> +# ifndef __ASSEMBLER__
> +# define __SC_THREAD_STACK_MIN_VALUE 75
> +__BEGIN_DECLS
> +extern long int __sysconf (int __name) __THROW;
> +__END_DECLS
> +# define PTHREAD_STACK_MIN __sysconf (__SC_THREAD_STACK_MIN_VALUE)
OK. Decouple from the actual definition of the sysconf value.
> +# endif
> +# else
> +# include <bits/pthread_stack_min.h>
> +# endif
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/include/bits/pthread_stack_min-dynamic.h b/sysdeps/unix/sysv/linux/include/bits/pthread_stack_min-dynamic.h
> new file mode 100644
> index 0000000000..d66f584b21
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/include/bits/pthread_stack_min-dynamic.h
> @@ -0,0 +1,7 @@
> +/* Don't define PTHREAD_STACK_MIN to __sysconf (_SC_THREAD_STACK_MIN)
> + for glibc build. */
> +#ifdef _ISOMAC
> +# include <sysdeps/unix/sysv/linux/bits/pthread_stack_min-dynamic.h>
> +#else
> +# include <bits/pthread_stack_min.h>
> +#endif
>
OK.
deleted file mode 100644
@@ -1,7 +0,0 @@
-/* Don't define PTHREAD_STACK_MIN to sysconf (_SC_THREAD_STACK_MIN) for
- glibc build. */
-#if !defined _ISOMAC
-# undef __USE_DYNAMIC_STACK_SIZE
-#endif
-
-#include_next <bits/local_lim.h>
@@ -24,6 +24,9 @@
#include <support/check.h>
#include <support/xthread.h>
+_Static_assert (__SC_THREAD_STACK_MIN_VALUE == _SC_THREAD_STACK_MIN,
+ "__SC_THREAD_STACK_MIN_VALUE is correct");
+
static void *
threadfunc (void *closure)
{
@@ -29,7 +29,9 @@
#include <bits/types/struct_timespec.h>
#include <bits/types/__sigset_t.h>
#include <bits/types/struct___jmp_buf_tag.h>
-
+#ifdef __USE_MISC
+# include <bits/pthread_stack_min-dynamic.h>
+#endif
/* Detach state. */
enum
@@ -109,7 +109,7 @@ sysdep_headers += sys/mount.h sys/acct.h \
bits/types/struct_semid64_ds_helper.h \
bits/types/struct_shmid64_ds.h \
bits/types/struct_shmid64_ds_helper.h \
- bits/pthread_stack_min.h
+ bits/pthread_stack_min.h bits/pthread_stack_min-dynamic.h
tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
@@ -77,14 +77,8 @@
priority level. */
#define AIO_PRIO_DELTA_MAX 20
-/* Minimum size for a thread. We are free to choose a reasonable value. */
-#undef PTHREAD_STACK_MIN
-#if defined __USE_DYNAMIC_STACK_SIZE && __USE_DYNAMIC_STACK_SIZE
-# include <unistd.h>
-# define PTHREAD_STACK_MIN sysconf (_SC_THREAD_STACK_MIN)
-#else
-# include <bits/pthread_stack_min.h>
-#endif
+/* Arrange for the definition of PTHREAD_STACK_MIN. */
+#include <bits/pthread_stack_min-dynamic.h>
/* Maximum number of timer expiration overruns. */
#define DELAYTIMER_MAX 2147483647
new file mode 100644
@@ -0,0 +1,31 @@
+/* Definition of PTHREAD_STACK_MIN, possibly dynamic.
+ Copyright (C) 2021 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
+ <https://www.gnu.org/licenses/>. */
+
+#ifndef PTHREAD_STACK_MIN
+# if defined __USE_DYNAMIC_STACK_SIZE && __USE_DYNAMIC_STACK_SIZE
+# ifndef __ASSEMBLER__
+# define __SC_THREAD_STACK_MIN_VALUE 75
+__BEGIN_DECLS
+extern long int __sysconf (int __name) __THROW;
+__END_DECLS
+# define PTHREAD_STACK_MIN __sysconf (__SC_THREAD_STACK_MIN_VALUE)
+# endif
+# else
+# include <bits/pthread_stack_min.h>
+# endif
+#endif
new file mode 100644
@@ -0,0 +1,7 @@
+/* Don't define PTHREAD_STACK_MIN to __sysconf (_SC_THREAD_STACK_MIN)
+ for glibc build. */
+#ifdef _ISOMAC
+# include <sysdeps/unix/sysv/linux/bits/pthread_stack_min-dynamic.h>
+#else
+# include <bits/pthread_stack_min.h>
+#endif