Messages in this thread | | | Subject | Re: [PATCH bpf] samples/bpf: Fix the error return code of xdp_redirect's main() | From | "wanghai (M)" <> | Date | Mon, 5 Jul 2021 15:45:07 +0800 |
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在 2021/7/2 18:29, Jesper Dangaard Brouer 写道: > > On 16/06/2021 06.25, Wang Hai wrote: >> Fix to return a negative error code from the error handling >> case instead of 0, as done elsewhere in this function. > > The main() function in C should never return a negative value on Unix > POSIX systems. > > > There is a good explaination in exit(3p): `man 3p exit` > > The value of status may be 0, EXIT_SUCCESS, EXIT_FAILURE, or any > other value, though only the least significant 8 bits (that is, status > & 0377) shall be available to a waiting parent process. > > Thus, negative values are often seen as 255 in the $? program exit > status variable $?. > > > Also explained in exit(3): > > The C standard specifies two constants, EXIT_SUCCESS=0 and > EXIT_FAILURE=1. > > I see the 'samples/bpf/xdp_redirect_user.c' in most places just use 0 > or 1. > Got it, thanks for the explanation, I will fix it to return 1, just like the other error paths in samples/bpf/xdp_redirect_user.c > >> If bpf_map_update_elem() failed, main() should return a negative error. >> >> Fixes: 832622e6bd18 ("xdp: sample program for new bpf_redirect helper") >> Signed-off-by: Wang Hai <wanghai38@huawei.com> >> --- >> samples/bpf/xdp_redirect_user.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/samples/bpf/xdp_redirect_user.c >> b/samples/bpf/xdp_redirect_user.c >> index 41d705c3a1f7..c903f1ccc15e 100644 >> --- a/samples/bpf/xdp_redirect_user.c >> +++ b/samples/bpf/xdp_redirect_user.c >> @@ -213,5 +213,5 @@ int main(int argc, char **argv) >> poll_stats(2, ifindex_out); >> out: >> - return 0; >> + return ret; >> } > > > (Sorry, I didn't complain it time as I see this patch is already applied) > > . >
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