Re: [PATCH v3 3/3] selftests/bpf: Prepare to add -Wsign-compare for bpf tests

From: Mehdi Ben Hadj Khelifa
Date: Thu Sep 25 2025 - 11:31:59 EST

On 9/25/25 4:04 PM, Daniel Borkmann wrote:
On 9/25/25 12:35 PM, Mehdi Ben Hadj Khelifa wrote:
-Change only variable types for correct sign comparisons

Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@xxxxxxxxx>

Pls write some better commit messages and not just copy/paste the same $subj/
message every time; proper sentences w/o the weird " -" indent.

Understood, though the changes are very similar / are the same with the same goal that's why it made sense to me to do that and I will remove the - in future commits.> Also say
why
this is needed in the commit message, and add a reference to the commit which
initially added this as a TODO, i.e. 495d2d8133fd ("selftests/bpf: Attempt to
build BPF programs with -Wsign-compare").
I will do that in the upcoming version.

If you group these, then maybe also
include the parts of the compiler-emitted warnings during build which are
relevant to the code changes you do here.

Okay. I will do that. Should i send a v4 with the recommended changes but not including the rest of the files meaning the ones that I haven't uploaded in this patch series which contain type casting or should i just make changes for these files in this series?
Also will it be better if dropped these versions and made a new patch with v1?

Thank you for your review and time Daniel.
Regards,
Mehdi
---
  tools/testing/selftests/bpf/progs/test_xdp_dynptr.c          | 2 +-
  tools/testing/selftests/bpf/progs/test_xdp_loop.c            | 2 +-
  tools/testing/selftests/bpf/progs/test_xdp_noinline.c        | 4 ++--
  tools/testing/selftests/bpf/progs/uprobe_multi.c             | 4 ++--
  .../selftests/bpf/progs/uprobe_multi_session_recursive.c     | 5 +++--
  .../selftests/bpf/progs/verifier_iterating_callbacks.c       | 2 +-
  6 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_xdp_dynptr.c b/ tools/testing/selftests/bpf/progs/test_xdp_dynptr.c
index 67a77944ef29..12ad0ec91021 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_dynptr.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_dynptr.c
@@ -89,7 +89,7 @@ static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xd
      struct vip vip = {};
      int dport;
      __u32 csum = 0;
-    int i;
+    size_t i;
      __builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
      __builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp));
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_loop.c b/ tools/testing/selftests/bpf/progs/test_xdp_loop.c
index 93267a68825b..e9b7bbff5c23 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_loop.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_loop.c
@@ -85,7 +85,7 @@ static __always_inline int handle_ipv4(struct xdp_md *xdp)
      struct vip vip = {};
      int dport;
      __u32 csum = 0;
-    int i;
+    size_t i;
      if (iph + 1 > data_end)
          return XDP_DROP;
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_noinline.c b/ tools/testing/selftests/bpf/progs/test_xdp_noinline.c
index fad94e41cef9..85ef3c0a3e20 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_noinline.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_noinline.c
@@ -372,7 +372,7 @@ bool encap_v4(struct xdp_md *xdp, struct ctl_value *cval,
      next_iph_u16 = (__u16 *) iph;
      __pragma_loop_unroll_full
-    for (int i = 0; i < sizeof(struct iphdr) >> 1; i++)
+    for (size_t i = 0; i < sizeof(struct iphdr) >> 1; i++)
          csum += *next_iph_u16++;
      iph->check = ~((csum & 0xffff) + (csum >> 16));
      if (bpf_xdp_adjust_head(xdp, (int)sizeof(struct iphdr)))
@@ -423,7 +423,7 @@ int send_icmp_reply(void *data, void *data_end)
      iph->check = 0;
      next_iph_u16 = (__u16 *) iph;
      __pragma_loop_unroll_full
-    for (int i = 0; i < sizeof(struct iphdr) >> 1; i++)
+    for (size_t i = 0; i < sizeof(struct iphdr) >> 1; i++)
          csum += *next_iph_u16++;
      iph->check = ~((csum & 0xffff) + (csum >> 16));
      return swap_mac_and_send(data, data_end);
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi.c b/tools/ testing/selftests/bpf/progs/uprobe_multi.c
index 44190efcdba2..f99957773c3a 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi.c
@@ -20,13 +20,13 @@ __u64 uretprobe_multi_func_3_result = 0;
  __u64 uprobe_multi_sleep_result = 0;
-int pid = 0;
+__u32 pid = 0;
  int child_pid = 0;
  int child_tid = 0;
  int child_pid_usdt = 0;
  int child_tid_usdt = 0;
-int expect_pid = 0;
+__u32 expect_pid = 0;
  bool bad_pid_seen = false;
  bool bad_pid_seen_usdt = false;
diff --git a/tools/testing/selftests/bpf/progs/ uprobe_multi_session_recursive.c b/tools/testing/selftests/bpf/progs/ uprobe_multi_session_recursive.c
index 8fbcd69fae22..017f1859ebe8 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
@@ -3,6 +3,7 @@
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_tracing.h>
  #include <stdbool.h>
+#include <stddef.h>
  #include "bpf_kfuncs.h"
  #include "bpf_misc.h"
@@ -10,8 +11,8 @@ char _license[] SEC("license") = "GPL";
  int pid = 0;
-int idx_entry = 0;
-int idx_return = 0;
+size_t idx_entry = 0;
+size_t idx_return = 0;
  __u64 test_uprobe_cookie_entry[6];
  __u64 test_uprobe_cookie_return[3];
diff --git a/tools/testing/selftests/bpf/progs/ verifier_iterating_callbacks.c b/tools/testing/selftests/bpf/progs/ verifier_iterating_callbacks.c
index 75dd922e4e9f..72f9f8c23c93 100644
--- a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
+++ b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c
@@ -593,7 +593,7 @@ int loop_inside_iter_volatile_limit(const void *ctx)
  {
      struct bpf_iter_num it;
      int *v, sum = 0;
-    __u64 i = 0;
+    __s32 i = 0;
      bpf_iter_num_new(&it, 0, ARR2_SZ);
      while ((v = bpf_iter_num_next(&it))) {