Attachment 118120 Details for Bug 91869 – Patch to use __attribute__((destructor)) in ralloc.c

[patch] Patch to use __attribute__((destructor)) in ralloc.c

0001-ralloc-Use-__attribute__-destructor-instead-of-atexi.patch (text/plain), 3.20 KB, created by Jean-Sébastien Pédron on 2015-09-07 09:00:14 UTC

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Creator: Jean-Sébastien Pédron

Created: 2015-09-07 09:00:14 UTC

Size: 3.20 KB

patch

obsolete

>From eaa94147a822f9c56d5842d6ff601aa39cf05a63 Mon Sep 17 00:00:00 2001
>From: =?UTF-8?q?Jean-S=C3=A9bastien=20P=C3=A9dron?=
> <jean-sebastien.pedron@dumbbell.fr>
>Date: Wed, 2 Sep 2015 15:21:41 +0200
>Subject: [PATCH] ralloc: Use __attribute__((destructor)) instead of atexit(3)
>
>... to free the ralloc context at program exit.
>
>On Linux, atexit(3) handlers are called when the program exits but also
>when a library is unloaded. The latter behavior is a Glibc extension.
>
>On systems where this extension is not supported, this causes an
>application to crash when, for instance, a library using ralloc is
>dlclosed: at program exit, the registered function is no longer in
>memory. For example, this happens with OpenCL applications using an ICD
>loader on FreeBSD.
>
>__attribute__((destructor)) fixes the problem because such handlers are
>called when a library is unloaded and when the program exits.
>---
> configure.ac      | 1 +
> src/util/macros.h | 6 ++++++
> src/util/ralloc.c | 5 +++--
> src/util/ralloc.h | 9 ++++++---
> 4 files changed, 16 insertions(+), 5 deletions(-)
>
>diff --git a/configure.ac b/configure.ac
>index 90ba4fe..f4ab843 100644
>--- a/configure.ac
>+++ b/configure.ac
>@@ -209,6 +209,7 @@ AX_GCC_BUILTIN([__builtin_popcountll])
> AX_GCC_BUILTIN([__builtin_unreachable])
> 
> AX_GCC_FUNC_ATTRIBUTE([const])
>+AX_GCC_FUNC_ATTRIBUTE([destructor])
> AX_GCC_FUNC_ATTRIBUTE([flatten])
> AX_GCC_FUNC_ATTRIBUTE([format])
> AX_GCC_FUNC_ATTRIBUTE([malloc])
>diff --git a/src/util/macros.h b/src/util/macros.h
>index 84e4f18..539aba4 100644
>--- a/src/util/macros.h
>+++ b/src/util/macros.h
>@@ -114,6 +114,12 @@ do {                       \
> #define ATTRIBUTE_CONST
> #endif
> 
>+#ifdef HAVE_FUNC_ATTRIBUTE_DESTRUCTOR
>+#define DESTRUCTOR __attribute__((destructor))
>+#else
>+#define DESTRUCTOR
>+#endif
>+
> #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
> #define FLATTEN __attribute__((__flatten__))
> #else
>diff --git a/src/util/ralloc.c b/src/util/ralloc.c
>index 01719c8..09b9524 100644
>--- a/src/util/ralloc.c
>+++ b/src/util/ralloc.c
>@@ -311,7 +311,7 @@ ralloc_parent(const void *ptr)
> 
> static void *autofree_context = NULL;
> 
>-static void
>+static DESTRUCTOR void
> autofree(void)
> {
>    ralloc_free(autofree_context);
>@@ -322,7 +322,8 @@ ralloc_autofree_context(void)
> {
>    if (unlikely(autofree_context == NULL)) {
>       autofree_context = ralloc_context(NULL);
>-      atexit(autofree);
>+      /* autofree_context is freed at program exit or library unload in
>+       * autofree() above. */
>    }
>    return autofree_context;
> }
>diff --git a/src/util/ralloc.h b/src/util/ralloc.h
>index 7587e11..d8c6cc0 100644
>--- a/src/util/ralloc.h
>+++ b/src/util/ralloc.h
>@@ -249,9 +249,12 @@ void *ralloc_parent(const void *ptr);
> /**
>  * Return a context whose memory will be automatically freed at program exit.
>  *
>- * The first call to this function creates a context and registers a handler
>- * to free it using \c atexit.  This may cause trouble if used in a library
>- * loaded with \c dlopen.
>+ * The first call to this function creates a context.
>+ *
>+ * The context is freed in a function registered with
>+ * \c __attribute__((destructor)). \c atexit is not used for this
>+ * purpose as it would crash when used in a library loaded with
>+ * \c dlopen.
>  */
> void *ralloc_autofree_context(void);
> 
>-- 
>2.4.6
>

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Attachments on bug 91869: 118072 | 118120

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