Yonghong Song <yhs@xxxxxx> writes: > On 12/16/19 4:40 AM, Toke Høiland-Jørgensen wrote: >> Probably the single most common error newcomers to XDP are stumped by is >> the 'permission denied' error they get when trying to load their program >> and 'ulimit -r' is set too low. For examples, see [0], [1]. >> >> Since the error code is UAPI, we can't change that. Instead, this patch >> adds a few heuristics in libbpf and outputs an additional hint if they are >> met: If an EPERM is returned on map create or program load, and geteuid() >> shows we are root, and the current RLIMIT_MEMLOCK is not infinity, we >> output a hint about raising 'ulimit -r' as an additional log line. >> >> [0] https://marc.info/?l=xdp-newbies&m=157043612505624&w=2 >> [1] https://github.com/xdp-project/xdp-tutorial/issues/86 >> >> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> > > LGTM with one minor no-essential suggestion below. > > Acked-by: Yonghong Song <yhs@xxxxxx> > >> --- >> tools/lib/bpf/libbpf.c | 21 +++++++++++++++++++++ >> 1 file changed, 21 insertions(+) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index a2cc7313763a..aec7995674d2 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -41,6 +41,7 @@ >> #include <sys/types.h> >> #include <sys/vfs.h> >> #include <sys/utsname.h> >> +#include <sys/resource.h> >> #include <tools/libc_compat.h> >> #include <libelf.h> >> #include <gelf.h> >> @@ -100,6 +101,24 @@ void libbpf_print(enum libbpf_print_level level, const char *format, ...) >> va_end(args); >> } >> >> +static void pr_perm_msg(int err) >> +{ >> + struct rlimit limit; >> + >> + if (err != -EPERM || geteuid() != 0) >> + return; >> + >> + err = getrlimit(RLIMIT_MEMLOCK, &limit); >> + if (err) >> + return; >> + >> + if (limit.rlim_cur == RLIM_INFINITY) >> + return; >> + >> + pr_warn("permission error while running as root; try raising 'ulimit -r'? current value: %lu\n", >> + limit.rlim_cur); > > Here we print out in terms of bytes. Maybe in terms of kilo bytes or > mega bytes is more user friendly, esp. we want them to set a different > value? Yeah, thought about that, but was too lazy to actually implement it :) Can send a v2 with that added... -Toke
