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

[Daniel Borkmann <daniel@iogearbox.net>]

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@gmail.com>

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

> ---
>   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))) {