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Date: Sun, 29 Sep 2013 16:26:13 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Markus Trippelsdorf <markus@...ppelsdorf.de>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Andi Kleen <ak@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [GIT PULL] perf fix
* Markus Trippelsdorf <markus@...ppelsdorf.de> wrote:
> On 2013.09.28 at 20:03 +0200, Ingo Molnar wrote:
> > Andi Kleen (1):
> > perf symbols: Demangle cloned functions
>
> The commit above e95ab53645:
>
> commit de95ab53645a2f0015e0f68ee723f18dce2b8b51
> Author: Andi Kleen <ak@...ux.intel.com>
> Date: Thu Sep 12 08:16:38 2013 -0700
>
> perf symbols: Demangle cloned functions
>
> breaks "perf top" on my machine. I just see a gray screen with no text
> at all. Sometimes the following error messages are printed:
> *** Error in `perf': invalid fastbin entry (free): 0x00000000029b18c0 ***
> *** Error in `perf': malloc(): memory corruption (fast): 0x0000000000ee0b10 ***
>
> Reverting the commit "fixes" the issue.
Sorry about that.
Looking at the commit it fails on several quality levels:
- sloppy structure: the code is unreadable, it should have been a
separate helper function
- sloppy flow: why the heck does it do strchr() twice? Not to
mention the fragile way of how the new flow tries
to merge with the old instead of cleanly separating.
- sloppy types: it casts a const char * over into char *
- sloppy style: variable block not separated from statements,
meaningless temporary variable names, etc. etc.
- and it's not even a regression fix to begin with!
So the right resolution is a revert. Andi, please send a fixed patch with
all of these issues and the crash fixed.
Linus,
Please pull the latest perf-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus
HEAD: 14951f22f1cc8375ead345d2ca08455e91f2152b Revert "perf symbols: Demangle cloned functions"
It fixes the 'perf top' regression Markus Trippelsdorf reported.
Thanks,
Ingo
------------------>
Ingo Molnar (1):
Revert "perf symbols: Demangle cloned functions"
tools/perf/util/symbol-elf.c | 27 +--------------------------
1 file changed, 1 insertion(+), 26 deletions(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index d2a888e..a9c829b 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -928,33 +928,8 @@ int dso__load_sym(struct dso *dso, struct map *map,
* to it...
*/
if (symbol_conf.demangle) {
- /*
- * The demangler doesn't deal with cloned functions.
- * XXXX.clone.NUM or similar
- * Strip the dot part and readd it later.
- */
- char *p = (char *)elf_name, *dot;
- dot = strchr(elf_name, '.');
- if (dot) {
- p = strdup(elf_name);
- if (!p)
- goto new_symbol;
- dot = strchr(p, '.');
- *dot = 0;
- }
-
- demangled = bfd_demangle(NULL, p,
+ demangled = bfd_demangle(NULL, elf_name,
DMGL_PARAMS | DMGL_ANSI);
- if (dot)
- *dot = '.';
- if (demangled && dot) {
- demangled = realloc(demangled, strlen(demangled) + strlen(dot) + 1);
- if (!demangled)
- goto new_symbol;
- strcpy(demangled + (dot - p), dot);
- }
- if (p != elf_name)
- free(p);
if (demangled != NULL)
elf_name = demangled;
}
--
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