perf: Always feature test reallocarray

BugLink: https://bugs.launchpad.net/bugs/2107212

[ Upstream commit 4c4c072 ]

This is also used in util/comm.c now, so instead of selectively doing
the feature test, always do it. If it's ever used anywhere else it's
less likely to cause another build failure.

This doesn't remove the need to manually include libc_compat.h, and
missing that will still cause an error for glibc < 2.26. There isn't a
way to fix that without poisoning reallocarray like libbpf did, but that
has other downsides like making memory debugging tools less useful. So
for Perf keep it like this and we'll have to fix up any missed includes.

Fixes the following build error:

  util/comm.c:152:31: error: implicit declaration of function
                      'reallocarray' [-Wimplicit-function-declaration]
  152 |                         tmp = reallocarray(comm_strs->strs,
      |                               ^~~~~~~~~~~~

Fixes: 13ca628 ("perf comm: Add reference count checking to 'struct comm_str'")
Reported-by: Ali Utku Selen <[email protected]>
Signed-off-by: James Clark <[email protected]>
Reviewed-by: Ian Rogers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Manuel Diewald <[email protected]>
Signed-off-by: Timo Aaltonen <[email protected]>

Author: james-c-linaro

tools/perf/Makefile.config

@@ -497,13 +497,14 @@ ifeq ($(feature-setns), 1)
   $(call detected,CONFIG_SETNS)
 endif
 
+ifeq ($(feature-reallocarray), 0)
+  CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
+endif
+
 ifdef CORESIGHT
   $(call feature_check,libopencsd)
   ifeq ($(feature-libopencsd), 1)
     CFLAGS += -DHAVE_CSTRACE_SUPPORT $(LIBOPENCSD_CFLAGS)
-    ifeq ($(feature-reallocarray), 0)
-      CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
-    endif
     LDFLAGS += $(LIBOPENCSD_LDFLAGS)
     EXTLIBS += $(OPENCSDLIBS)
     $(call detected,CONFIG_LIBOPENCSD)
@@ -1110,9 +1111,6 @@ ifndef NO_AUXTRACE
   ifndef NO_AUXTRACE
     $(call detected,CONFIG_AUXTRACE)
     CFLAGS += -DHAVE_AUXTRACE_SUPPORT
-    ifeq ($(feature-reallocarray), 0)
-      CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
-    endif
   endif
 endif
 

tools/perf/util/comm.c

@@ -5,6 +5,8 @@
 #include <internal/rc_check.h>
 #include <linux/refcount.h>
 #include <linux/zalloc.h>
+#include <tools/libc_compat.h> // reallocarray
+
 #include "rwsem.h"
 
 DECLARE_RC_STRUCT(comm_str) {