linux-kernel - [PATCH bpf-next v2 29/35] bpf: libbpf: cleanup RLIMIT

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Message-ID: <20200727184506.2279656-30-guro@fb.com>
Date:   Mon, 27 Jul 2020 11:45:00 -0700
From:   Roman Gushchin <guro@...com>
To:     <bpf@...r.kernel.org>
CC:     <netdev@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        <linux-kernel@...r.kernel.org>, Roman Gushchin <guro@...com>
Subject: [PATCH bpf-next v2 29/35] bpf: libbpf: cleanup RLIMIT_MEMLOCK usage

As bpf is not using memlock rlimit for memory accounting anymore,
let's remove the related code from libbpf.

Bpf operations can't fail because of exceeding the limit anymore.

Signed-off-by: Roman Gushchin <guro@...com>
---
 tools/lib/bpf/libbpf.c | 31 +------------------------------
 tools/lib/bpf/libbpf.h |  5 -----
 2 files changed, 1 insertion(+), 35 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e51479d60285..841060f5cee3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -112,32 +112,6 @@ void libbpf_print(enum libbpf_print_level level, const char *format, ...)
 	va_end(args);
 }
 
-static void pr_perm_msg(int err)
-{
-	struct rlimit limit;
-	char buf[100];
-
-	if (err != -EPERM || geteuid() != 0)
-		return;
-
-	err = getrlimit(RLIMIT_MEMLOCK, &limit);
-	if (err)
-		return;
-
-	if (limit.rlim_cur == RLIM_INFINITY)
-		return;
-
-	if (limit.rlim_cur < 1024)
-		snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
-	else if (limit.rlim_cur < 1024*1024)
-		snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
-	else
-		snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
-
-	pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
-		buf);
-}
-
 #define STRERR_BUFSIZE  128
 
 /* Copied from tools/perf/util/util.h */
@@ -3420,8 +3394,7 @@ bpf_object__probe_loading(struct bpf_object *obj)
 		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
 		pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
 			"program. Make sure your kernel supports BPF "
-			"(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "
-			"set to big enough value.\n", __func__, cp, ret);
+			"(CONFIG_BPF_SYSCALL=y)", __func__, cp, ret);
 		return -ret;
 	}
 	close(ret);
@@ -3918,7 +3891,6 @@ bpf_object__create_maps(struct bpf_object *obj)
 err_out:
 	cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
 	pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
-	pr_perm_msg(err);
 	for (j = 0; j < i; j++)
 		zclose(obj->maps[j].fd);
 	return err;
@@ -5419,7 +5391,6 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	ret = -errno;
 	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
 	pr_warn("load bpf program failed: %s\n", cp);
-	pr_perm_msg(ret);
 
 	if (log_buf && log_buf[0] != '\0') {
 		ret = -LIBBPF_ERRNO__VERIFY;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index c6813791fa7e..8d2f1194cb02 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -610,11 +610,6 @@ bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
 
 /*
  * Probe for supported system features
- *
- * Note that running many of these probes in a short amount of time can cause
- * the kernel to reach the maximal size of lockable memory allowed for the
- * user, causing subsequent probes to fail. In this case, the caller may want
- * to adjust that limit with setrlimit().
  */
 LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
 				    __u32 ifindex);
-- 
2.26.2