* libbacktrace patch committed: Graceful fallback if out of memory
@ 2015-09-08 17:15 Ian Lance Taylor
2015-09-09 0:35 ` Hans-Peter Nilsson
0 siblings, 1 reply; 3+ messages in thread
From: Ian Lance Taylor @ 2015-09-08 17:15 UTC (permalink / raw)
To: gcc-patches
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I've committed this libbacktrace patch to mainline to do a graceful
fallback if no memory can be allocated. In that case we print out the
PC addresses without trying to resolve file/line information. This is
imperfect but better than the earlier behaviour of producing a series
of error messages. Tested with libbacktrace and Go testsuites.
Committed to mainline.
Ian
2015-09-08 Ian Lance Taylor <iant@google.com>
PR other/67457
* backtrace.c: #include "internal.h".
(struct backtrace_data): Add can_alloc field.
(unwind): If can_alloc is false, don't try to get file/line
information.
(backtrace_full): Set can_alloc field in bdata.
* alloc.c (backtrace_alloc): Don't call error_callback if it is
NULL.
* mmap.c (backtrace_alloc): Likewise.
* internal.h: Update comments for backtrace_alloc and
backtrace_free.
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Index: alloc.c
===================================================================
--- alloc.c (revision 227528)
+++ alloc.c (working copy)
@@ -44,7 +44,8 @@ POSSIBILITY OF SUCH DAMAGE. */
backtrace functions may not be safely invoked from a signal
handler. */
-/* Allocate memory like malloc. */
+/* Allocate memory like malloc. If ERROR_CALLBACK is NULL, don't
+ report an error. */
void *
backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
@@ -55,7 +56,10 @@ backtrace_alloc (struct backtrace_state
ret = malloc (size);
if (ret == NULL)
- error_callback (data, "malloc", errno);
+ {
+ if (error_callback)
+ error_callback (data, "malloc", errno);
+ }
return ret;
}
Index: backtrace.c
===================================================================
--- backtrace.c (revision 227528)
+++ backtrace.c (working copy)
@@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE. */
#include "unwind.h"
#include "backtrace.h"
+#include "internal.h"
/* The main backtrace_full routine. */
@@ -53,6 +54,8 @@ struct backtrace_data
void *data;
/* Value to return from backtrace_full. */
int ret;
+ /* Whether there is any memory available. */
+ int can_alloc;
};
/* Unwind library callback routine. This is passed to
@@ -80,8 +83,11 @@ unwind (struct _Unwind_Context *context,
if (!ip_before_insn)
--pc;
- bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback,
- bdata->error_callback, bdata->data);
+ if (!bdata->can_alloc)
+ bdata->ret = bdata->callback (bdata->data, pc, NULL, 0, NULL);
+ else
+ bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback,
+ bdata->error_callback, bdata->data);
if (bdata->ret != 0)
return _URC_END_OF_STACK;
@@ -96,6 +102,7 @@ backtrace_full (struct backtrace_state *
backtrace_error_callback error_callback, void *data)
{
struct backtrace_data bdata;
+ void *p;
bdata.skip = skip + 1;
bdata.state = state;
@@ -103,6 +110,18 @@ backtrace_full (struct backtrace_state *
bdata.error_callback = error_callback;
bdata.data = data;
bdata.ret = 0;
+
+ /* If we can't allocate any memory at all, don't try to produce
+ file/line information. */
+ p = backtrace_alloc (state, 4096, NULL, NULL);
+ if (p == NULL)
+ bdata.can_alloc = 0;
+ else
+ {
+ backtrace_free (state, p, 4096, NULL, NULL);
+ bdata.can_alloc = 1;
+ }
+
_Unwind_Backtrace (unwind, &bdata);
return bdata.ret;
}
Index: internal.h
===================================================================
--- internal.h (revision 227528)
+++ internal.h (working copy)
@@ -201,13 +201,15 @@ extern int backtrace_close (int descript
extern void backtrace_qsort (void *base, size_t count, size_t size,
int (*compar) (const void *, const void *));
-/* Allocate memory. This is like malloc. */
+/* Allocate memory. This is like malloc. If ERROR_CALLBACK is NULL,
+ this does not report an error, it just returns NULL. */
extern void *backtrace_alloc (struct backtrace_state *state, size_t size,
backtrace_error_callback error_callback,
void *data) ATTRIBUTE_MALLOC;
-/* Free memory allocated by backtrace_alloc. */
+/* Free memory allocated by backtrace_alloc. If ERROR_CALLBACK is
+ NULL, this does not report an error. */
extern void backtrace_free (struct backtrace_state *state, void *mem,
size_t size,
Index: mmap.c
===================================================================
--- mmap.c (revision 227529)
+++ mmap.c (working copy)
@@ -77,7 +77,8 @@ backtrace_free_locked (struct backtrace_
}
}
-/* Allocate memory like malloc. */
+/* Allocate memory like malloc. If ERROR_CALLBACK is NULL, don't
+ report an error. */
void *
backtrace_alloc (struct backtrace_state *state,
@@ -140,7 +141,10 @@ backtrace_alloc (struct backtrace_state
page = mmap (NULL, asksize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (page == MAP_FAILED)
- error_callback (data, "mmap", errno);
+ {
+ if (error_callback)
+ error_callback (data, "mmap", errno);
+ }
else
{
size = (size + 7) & ~ (size_t) 7;
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: libbacktrace patch committed: Graceful fallback if out of memory
2015-09-08 17:15 libbacktrace patch committed: Graceful fallback if out of memory Ian Lance Taylor
@ 2015-09-09 0:35 ` Hans-Peter Nilsson
2015-09-09 4:12 ` Ian Lance Taylor
0 siblings, 1 reply; 3+ messages in thread
From: Hans-Peter Nilsson @ 2015-09-09 0:35 UTC (permalink / raw)
To: iant; +Cc: gcc-patches
> From: Ian Lance Taylor <iant@google.com>
> Date: Tue, 8 Sep 2015 18:46:21 +0200
> PR other/67457
> * backtrace.c: #include "internal.h".
> (struct backtrace_data): Add can_alloc field.
> (unwind): If can_alloc is false, don't try to get file/line
> information.
> (backtrace_full): Set can_alloc field in bdata.
> * alloc.c (backtrace_alloc): Don't call error_callback if it is
> NULL.
> * mmap.c (backtrace_alloc): Likewise.
> * internal.h: Update comments for backtrace_alloc and
> backtrace_free.
> Index: backtrace.c
> ===================================================================
> --- backtrace.c (revision 227528)
> +++ backtrace.c (working copy)
> @@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE. */
>
> #include "unwind.h"
> #include "backtrace.h"
> +#include "internal.h"
>
> /* The main backtrace_full routine. */
>
I don't know about your environment, but for me (cross from
x86_64-linux to cris-elf) that causes a:
/bin/sh ./libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I/tmp/hpautotest-gcc0/gcc/libbacktrace -I /tmp/hpautotest-gcc0/gcc/libbacktrace/../include -I /tmp/hpautotest-gcc0/gcc/libbacktrace/../libgcc -I ../libgcc -funwind-tables -frandom-seed=backtrace.lo -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -Wcast-qual -g -O2 -c -o backtrace.lo /tmp/hpautotest-gcc0/gcc/libbacktrace/backtrace.c
libtool: compile: gcc -DHAVE_CONFIG_H -I. -I/tmp/hpautotest-gcc0/gcc/libbacktrace -I /tmp/hpautotest-gcc0/gcc/libbacktrace/../include -I /tmp/hpautotest-gcc0/gcc/libbacktrace/../libgcc -I ../libgcc -funwind-tables -frandom-seed=backtrace.lo -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -Wcast-qual -g -O2 -c /tmp/hpautotest-gcc0/gcc/libbacktrace/backtrace.c -fPIC -DPIC -o .libs/backtrace.o
In file included from /tmp/hpautotest-gcc0/gcc/libbacktrace/backtrace.c:37:
/tmp/hpautotest-gcc0/gcc/libbacktrace/internal.h:182: error: expected declaration specifiers or '...' before 'off_t'
make[3]: *** [backtrace.lo] Error 1
make[3]: Leaving directory `/tmp/hpautotest-gcc0/cris-elf/gccobj/libbacktrace'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/tmp/hpautotest-gcc0/cris-elf/gccobj/libbacktrace'
make[1]: *** [all-libbacktrace] Error 2
make[1]: Leaving directory `/tmp/hpautotest-gcc0/cris-elf/gccobj'
make: *** [all] Error 2
I've committed the following as obvious, following the pattern
of the other files including internal.h, after observing
all-libbacktrace (i.e. built for the host) complete.
libbacktrace:
* backtrace.c: #include <sys/types.h>.
Index: backtrace.c
===================================================================
--- backtrace.c (revision 227567)
+++ backtrace.c (working copy)
@@ -32,6 +32,8 @@ POSSIBILITY OF SUCH DAMAGE. */
#include "config.h"
+#include <sys/types.h>
+
#include "unwind.h"
#include "backtrace.h"
#include "internal.h"
brgds, H-P
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: libbacktrace patch committed: Graceful fallback if out of memory
2015-09-09 0:35 ` Hans-Peter Nilsson
@ 2015-09-09 4:12 ` Ian Lance Taylor
0 siblings, 0 replies; 3+ messages in thread
From: Ian Lance Taylor @ 2015-09-09 4:12 UTC (permalink / raw)
To: Hans-Peter Nilsson; +Cc: gcc-patches
On Tue, Sep 8, 2015 at 5:00 PM, Hans-Peter Nilsson
<hans-peter.nilsson@axis.com> wrote:
>
> I've committed the following as obvious, following the pattern
> of the other files including internal.h, after observing
> all-libbacktrace (i.e. built for the host) complete.
>
> libbacktrace:
> * backtrace.c: #include <sys/types.h>.
Thanks.
Ian
^ permalink raw reply [flat|nested] 3+ messages in thread
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