Fix erroneous (and circular) implied pattern rule for linkobj/libc.so.

[BZ #15915] As described in the bug, the pattern rule for lib%.so files
in Makerules includes linkobj/libc.so as a dependency.  However, the
explicit rule for linkobj/libc.so is in the top-level Makefile.

Thus, the subdirectory makefiles that include Makerules end up with an
erroneous makefile pattern rule for linkobj/libc.so that includes
itself as a dependency.  The result is make warnings whenever rules
for other .so files are resolved -- and, on occasion, actual makefile
failures when a race condition causes the implicit rule to actually be
used.

This patch moves the explicit rules for linkobj/libc.so into Makerules
to clear up this problem.  It also elaborates a couple of comments
that I'd initially found confusing.

diff --git a/ChangeLog b/ChangeLog
index beba952cb443dbb48a0e370b9001d52b848e5eff..12c24176796f6caa401132ab0067e4215d7b97f5 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-10-03  Brooks Moses  <bmoses@google.com>
+
+       [BZ #15915]
+       * Makefile (linkobj/libc_pic.a, linkobj/libc.so): Move rules to...
+       * Makerules: ...here, and adjust associated comments.
+
 2013-10-02  Will Newton  <will.newton@linaro.org>
 
        * malloc/Makefile: Add tst-pvalloc.

diff --git a/Makefile b/Makefile
index ba1820d2b25cacc8296059a161190aa8080d4599..302a300d48955b215a2172436fa57593b7b0bfc9 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -123,36 +123,7 @@ lib-noranlib: subdir_lib
 
 ifeq (yes,$(build-shared))
 # Build the shared object from the PIC object library.
-lib: $(common-objpfx)libc.so
-
-lib: $(common-objpfx)linkobj/libc.so
-
-# Do not filter ld.so out of libc.so link.
-$(common-objpfx)linkobj/libc.so: link-libc-deps = # empty
-
-$(common-objpfx)linkobj/libc.so: $(elfobjdir)/soinit.os \
-                                $(common-objpfx)linkobj/libc_pic.a \
-                                $(elfobjdir)/sofini.os \
-                                $(elfobjdir)/interp.os \
-                                $(elfobjdir)/ld.so \
-                                $(shlib-lds)
-       $(build-shlib)
-
-ifeq (,$(filter sunrpc,$(subdirs)))
-$(common-objpfx)linkobj/libc_pic.a: $(common-objpfx)libc_pic.a
-       $(make-target-directory)
-       ln -f $< $@
-else
-$(common-objpfx)linkobj/libc_pic.a: $(common-objpfx)libc_pic.a \
-                                   $(common-objpfx)sunrpc/librpc_compat_pic.a
-       $(make-target-directory)
-       (cd $(common-objpfx)linkobj; \
-        $(AR) x ../libc_pic.a; \
-        rm $$($(AR) t ../sunrpc/librpc_compat_pic.a | sed 's/^compat-//'); \
-        $(AR) x ../sunrpc/librpc_compat_pic.a; \
-        $(AR) cr libc_pic.a *.os; \
-        rm *.os)
-endif # $(subdirs) contains sunrpc
+lib: $(common-objpfx)libc.so $(common-objpfx)linkobj/libc.so
 endif # $(build-shared)
 
 

diff --git a/Makerules b/Makerules
index cca3f82799e305757f8bf3ed5112baf2eee5015a..92c287261264610a8c3c82c9c5a7667337600e5e 100644 (file)
--- a/Makerules
+++ b/Makerules
@@ -565,16 +565,47 @@ generated += libc_pic.opts libc_pic.os.clean
 libc_pic_clean := .clean
 endif
 
-# Do not filter ld.so out of libc.so link.
+# Build a possibly-modified version of libc_pic.a for use in building
+# linkobj/libc.so.
+ifeq (,$(filter sunrpc,$(subdirs)))
+$(common-objpfx)linkobj/libc_pic.a: $(common-objpfx)libc_pic.a
+       $(make-target-directory)
+       ln -f $< $@
+else
+$(common-objpfx)linkobj/libc_pic.a: $(common-objpfx)libc_pic.a \
+                                   $(common-objpfx)sunrpc/librpc_compat_pic.a
+       $(make-target-directory)
+       (cd $(common-objpfx)linkobj; \
+        $(AR) x ../libc_pic.a; \
+        rm $$($(AR) t ../sunrpc/librpc_compat_pic.a | sed 's/^compat-//'); \
+        $(AR) x ../sunrpc/librpc_compat_pic.a; \
+        $(AR) cr libc_pic.a *.os; \
+        rm *.os)
+endif # $(subdirs) contains sunrpc
+
+# Clear link-libc-deps for the libc.so libraries so build-shlibs does not
+# filter ld.so out of the list of linked objects.
 $(common-objpfx)libc.so: link-libc-deps = # empty
+$(common-objpfx)linkobj/libc.so: link-libc-deps = # empty
 
-# Use our own special initializer and finalizer files for libc.so.
+# Use our own special initializer and finalizer files for the libc.so
+# libraries.
 $(common-objpfx)libc.so: $(elfobjdir)/soinit.os \
                         $(common-objpfx)libc_pic.os$(libc_pic_clean) \
                         $(elfobjdir)/sofini.os \
-                        $(elfobjdir)/interp.os $(elfobjdir)/ld.so \
+                        $(elfobjdir)/interp.os \
+                        $(elfobjdir)/ld.so \
+                        $(shlib-lds)
+       $(build-shlib)
+
+$(common-objpfx)linkobj/libc.so: $(elfobjdir)/soinit.os \
+                        $(common-objpfx)linkobj/libc_pic.a \
+                        $(elfobjdir)/sofini.os \
+                        $(elfobjdir)/interp.os \
+                        $(elfobjdir)/ld.so \
                         $(shlib-lds)
        $(build-shlib)
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif