6.12-stable review patch. If anyone has any objections, please let me know.
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From: Luca Ceresoli luca.ceresoli@bootlin.com
[ Upstream commit 75100d848ef4b8ca39bb6dd3a21181e37dea27e2 ]
Building perf in-tree is broken after commit 890a1961c812 ("perf tools: Create source symlink in perf object dir") which added a 'source' symlink in the output dir pointing to the source dir.
With in-tree builds, the added 'SOURCE = ...' line is executed multiple times (I observed 2 during the build plus 2 during installation). This is a minor inefficiency, in theory not harmful because symlink creation is assumed to be idempotent. But it is not.
Considering with in-tree builds:
srctree=/absolute/path/to/linux OUTPUT=/absolute/path/to/linux/tools/perf
here's what happens:
1. ln -sf $(srctree)/tools/perf $(OUTPUT)/source -> creates /absolute/path/to/linux/tools/perf/source link to /absolute/path/to/linux/tools/perf => OK, that's what was intended 2. ln -sf $(srctree)/tools/perf $(OUTPUT)/source # same command as 1 -> creates /absolute/path/to/linux/tools/perf/perf link to /absolute/path/to/linux/tools/perf => Not what was intended, not idempotent 3. Now the build _should_ create the 'perf' executable, but it fails
The reason is the tricky 'ln' command line. At the first invocation 'ln' uses the 1st form:
ln [OPTION]... [-T] TARGET LINK_NAME
and creates a link to TARGET *called LINK_NAME*.
At the second invocation $(OUTPUT)/source exists, so 'ln' uses the 3rd form:
ln [OPTION]... TARGET... DIRECTORY
and creates a link to TARGET *called TARGET* inside DIRECTORY.
Fix by adding -n/--no-dereference to "treat LINK_NAME as a normal file if it is a symbolic link to a directory", as the manpage says.
Closes: https://lore.kernel.org/all/20241125182506.38af9907@booty/ Fixes: 890a1961c812 ("perf tools: Create source symlink in perf object dir") Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com Reviewed-by: Charlie Jenkins charlie@rivosinc.com Tested-by: Charlie Jenkins charlie@rivosinc.com Link: https://lore.kernel.org/r/20250124-perf-fix-intree-build-v1-1-485dd7a855e4@b... Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/Makefile.perf | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index 9dd2e8d3f3c9b..8ee59ecb14110 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -164,7 +164,7 @@ ifneq ($(OUTPUT),) VPATH += $(OUTPUT) export VPATH # create symlink to the original source -SOURCE := $(shell ln -sf $(srctree)/tools/perf $(OUTPUT)/source) +SOURCE := $(shell ln -sfn $(srctree)/tools/perf $(OUTPUT)/source) endif
ifeq ($(V),1)