Patch "perf lock contention: Change stack_id type to s32" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    perf lock contention: Change stack_id type to s32

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-lock-contention-change-stack_id-type-to-s32.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7760441d3e6dea392547fcc784206ffe85d0a4d7
Author: Namhyung Kim <namhyung@xxxxxxxxxx>
Date:   Mon Aug 12 10:25:33 2024 -0700

    perf lock contention: Change stack_id type to s32
    
    [ Upstream commit 040c0f887fdcfe747a3f63c94e9cd29e9ed0b872 ]
    
    The bpf_get_stackid() helper returns a signed type to check whether it
    failed to get a stacktrace or not.  But it saved the result in u32 and
    checked if the value is negative.
    
          376         if (needs_callstack) {
          377                 pelem->stack_id = bpf_get_stackid(ctx, &stacks,
          378                                                   BPF_F_FAST_STACK_CMP | stack_skip);
      --> 379                 if (pelem->stack_id < 0)
    
      ./tools/perf/util/bpf_skel/lock_contention.bpf.c:379 contention_begin()
      warn: unsigned 'pelem->stack_id' is never less than zero.
    
    Let's change the type to s32 instead.
    
    Fixes: 6d499a6b3d90277d ("perf lock: Print the number of lost entries for BPF")
    Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
    Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Cc: Ian Rogers <irogers@xxxxxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
    Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240812172533.2015291-1-namhyung@xxxxxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index 36af11faad03c..de12892f992f8 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -7,11 +7,11 @@ struct tstamp_data {
 	u64 timestamp;
 	u64 lock;
 	u32 flags;
-	u32 stack_id;
+	s32 stack_id;
 };
 
 struct contention_key {
-	u32 stack_id;
+	s32 stack_id;
 	u32 pid;
 	u64 lock_addr_or_cgroup;
 };
diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
index e9028235d7717..d818e30c54571 100644
--- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
+++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
@@ -15,6 +15,7 @@
 
 typedef __u8 u8;
 typedef __u32 u32;
+typedef __s32 s32;
 typedef __u64 u64;
 typedef __s64 s64;