[PATCH] tools/perf/build: Fix non-existent build directory handling

[Ingo Molnar <mingo@kernel.org>]

* Ingo Molnar <mingo@kernel.org> wrote:

> > It silently ignores the O= target, as it doesn't exists.
> > 
> > Previous, expected behaviour is for the build process to stop, 
> > complaining that the target directory doesn't exists.
> 
> Yeah. So the reproducer for me is:
> 
>  rm -rf /tmp/build
>  mkdir -p /tmp/build/perf
>  make O=/tmp/build/perf -C tools/perf/ install-bin
>  rm -rf /tmp/build
>  make O=/tmp/build/perf -C tools/perf/ install-bin
> 
> the second install-bin should fail, and on the old tree it fails correctly 
> - but with the new tree it pretends that it succeeds.
> 
> Looking into it.

does the patch below fix it?

Thanks,

	Ingo

=====================>
[PATCH] tools/perf/build: Fix non-existent build directory handling
From: Ingo Molnar <mingo@kernel.org>

Arnaldo reported that non-existent build directories were not recognized 
properly. The reason is readlink failure causing 'O' to become empty.

Solve it by passing through the 'O' variable unmodified if readlink fails.

Reported-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 5aa3d04..9147044 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -34,7 +34,7 @@ endif
 # Only pass canonical directory names as the output directory:
 #
 ifneq ($(O),)
-  FULL_O := $(shell readlink -f $(O))
+  FULL_O := $(shell readlink -f $(O) || echo $(O))
 endif
 
 define print_msg