[PATCH v8 03/10] Remove __morecore and __default_morecore
Carlos O'Donell
carlos@redhat.com
Sat Jul 17 22:03:52 GMT 2021
On 7/13/21 3:38 AM, Siddhesh Poyarekar wrote:
> Make the __morecore and __default_morecore symbols compat-only and
> remove their declarations from the API. Also, include morecore.c
> directly into malloc.c; this should ideally get merged into malloc in
> a future cleanup.
OK for 2.34.
Tested without regression on x86_64 and i686.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
> ---
> NEWS | 5 +++++
> include/stdlib.h | 3 ---
> malloc/Makefile | 2 +-
> malloc/arena.c | 12 ++----------
> malloc/hooks.c | 2 ++
> malloc/malloc.c | 7 +++----
> malloc/malloc.h | 8 --------
> malloc/morecore.c | 34 +++++++++++-----------------------
> 8 files changed, 24 insertions(+), 49 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index 13ffe627da..18d9e65eb2 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -113,6 +113,11 @@ Deprecated and removed features, and other changes affecting compatibility:
> mtrace. Similar functionality can be achieved by using conditional
> breakpoints within mtrace functions from within gdb.
>
> +* The __morecore and __after_morecore_hook malloc hooks and the default
> + implementation __default_morecore have been removed from the API. Existing
> + applications will continue to link against these symbols but the interfaces
> + no longer have any effect on malloc.
OK.
> +
> Changes to build and runtime requirements:
>
> * On Linux, the shm_open, sem_open, and related functions now expect the
> diff --git a/include/stdlib.h b/include/stdlib.h
> index 1f6e1508e4..1c6f70b082 100644
> --- a/include/stdlib.h
> +++ b/include/stdlib.h
> @@ -306,9 +306,6 @@ libc_hidden_proto (__qfcvt_r)
> # define MB_CUR_MAX (_NL_CURRENT_WORD (LC_CTYPE, _NL_CTYPE_MB_CUR_MAX))
> # endif
>
> -extern void *__default_morecore (ptrdiff_t) __THROW;
> -libc_hidden_proto (__default_morecore)
OK.
> -
> struct abort_msg_s
> {
> unsigned int size;
> diff --git a/malloc/Makefile b/malloc/Makefile
> index d15729569b..020f781b59 100644
> --- a/malloc/Makefile
> +++ b/malloc/Makefile
> @@ -104,7 +104,7 @@ tests-exclude-mcheck = tst-mallocstate \
> tests-mcheck = $(filter-out $(tests-exclude-mcheck), $(tests))
> endif
>
> -routines = malloc morecore mcheck mtrace obstack reallocarray \
> +routines = malloc mcheck mtrace obstack reallocarray \
OK.
> scratch_buffer_dupfree \
> scratch_buffer_grow scratch_buffer_grow_preserve \
> scratch_buffer_set_array_size \
> diff --git a/malloc/arena.c b/malloc/arena.c
> index 991fc21a7e..f1693ed48f 100644
> --- a/malloc/arena.c
> +++ b/malloc/arena.c
> @@ -274,14 +274,6 @@ next_env_entry (char ***position)
> #endif
>
>
> -#if defined(SHARED) || defined(USE_MTAG)
> -static void *
> -__failing_morecore (ptrdiff_t d)
> -{
> - return (void *) MORECORE_FAILURE;
> -}
> -#endif
> -
OK.
> #ifdef SHARED
> extern struct dl_open_hook *_dl_open_hook;
> libc_hidden_proto (_dl_open_hook);
> @@ -310,7 +302,7 @@ ptmalloc_init (void)
> and that morecore does not support tagged regions, then
> disable it. */
> if (__MTAG_SBRK_UNTAGGED)
> - __morecore = __failing_morecore;
> + __always_fail_morecore = true;
OK.
>
> mtag_enabled = true;
> mtag_mmap_flags = __MTAG_MMAP_FLAGS;
> @@ -323,7 +315,7 @@ ptmalloc_init (void)
> generic sbrk implementation also enforces this, but it is not
> used on Hurd. */
> if (!__libc_initial)
> - __morecore = __failing_morecore;
> + __always_fail_morecore = true;
OK.
> #endif
>
> thread_arena = &main_arena;
> diff --git a/malloc/hooks.c b/malloc/hooks.c
> index 45c91d6502..4aa6dadcff 100644
> --- a/malloc/hooks.c
> +++ b/malloc/hooks.c
> @@ -20,6 +20,8 @@
> #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
> void weak_variable (*__after_morecore_hook) (void) = NULL;
> compat_symbol (libc, __after_morecore_hook, __after_morecore_hook, GLIBC_2_0);
> +void *(*__morecore)(ptrdiff_t);
> +compat_symbol (libc, __morecore, __morecore, GLIBC_2_0);
OK.
> #endif
>
> /* Hooks for debugging versions. The initial hooks just call the
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index 24e7854a0e..6e8fa9e424 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -384,12 +384,11 @@ __malloc_assert (const char *assertion, const char *file, unsigned int line,
> #define TRIM_FASTBINS 0
> #endif
>
> -
> /* Definition for getting more memory from the OS. */
> -#define MORECORE (*__morecore)
> +#include "morecore.c"
> +
> +#define MORECORE (*__glibc_morecore)
OK.
> #define MORECORE_FAILURE 0
> -void * __default_morecore (ptrdiff_t);
> -void *(*__morecore)(ptrdiff_t) = __default_morecore;
OK.
>
> /* Memory tagging. */
>
> diff --git a/malloc/malloc.h b/malloc/malloc.h
> index 634b7db868..17ab9ee345 100644
> --- a/malloc/malloc.h
> +++ b/malloc/malloc.h
> @@ -76,14 +76,6 @@ extern void *valloc (size_t __size) __THROW __attribute_malloc__
> extern void *pvalloc (size_t __size) __THROW __attribute_malloc__
> __wur __attr_dealloc_free;
>
> -/* Underlying allocation function; successive calls should return
> - contiguous pieces of memory. */
> -extern void *(*__morecore) (ptrdiff_t __size) __MALLOC_DEPRECATED;
> -
> -/* Default value of `__morecore'. */
> -extern void *__default_morecore (ptrdiff_t __size)
> -__THROW __attribute_malloc__ __MALLOC_DEPRECATED;
OK.
> -
> /* SVID2/XPG mallinfo structure */
>
> struct mallinfo
> diff --git a/malloc/morecore.c b/malloc/morecore.c
> index 047228779b..8168ef158c 100644
> --- a/malloc/morecore.c
> +++ b/malloc/morecore.c
> @@ -15,39 +15,27 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#ifndef _MALLOC_INTERNAL
> -# define _MALLOC_INTERNAL
> -# include <malloc.h>
> -#endif
> -
> -#ifndef __GNU_LIBRARY__
> -# define __sbrk sbrk
> -#endif
> -
> -#ifdef __GNU_LIBRARY__
> -/* It is best not to declare this and cast its result on foreign operating
> - systems with potentially hostile include files. */
> -
> -# include <stddef.h>
> -# include <stdlib.h>
> -extern void *__sbrk (ptrdiff_t increment) __THROW;
> -libc_hidden_proto (__sbrk)
> -#endif
> -
> -#ifndef NULL
> -# define NULL 0
OK.
> +#if defined(SHARED) || defined(USE_MTAG)
> +static bool __always_fail_morecore = false;
> #endif
>
> /* Allocate INCREMENT more bytes of data space,
> and return the start of data space, or NULL on errors.
> If INCREMENT is negative, shrink data space. */
> void *
> -__default_morecore (ptrdiff_t increment)
> +__glibc_morecore (ptrdiff_t increment)
> {
> +#if defined(SHARED) || defined(USE_MTAG)
> + if (__always_fail_morecore)
> + return NULL;
> +#endif
OK.
> +
> void *result = (void *) __sbrk (increment);
> if (result == (void *) -1)
> return NULL;
>
> return result;
> }
> -libc_hidden_def (__default_morecore)
> +#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
> +compat_symbol (libc, __glibc_morecore, __default_morecore, GLIBC_2_0);
OK. Use a new name and create a versioned compat symbol for __default_morecore
in case someone calls it.
> +#endif
>
--
Cheers,
Carlos.
More information about the Libc-alpha
mailing list