7 files changed, 31 insertions, 2 deletions

diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst
index 3221be1b9ccc..64b001b4f777 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-map.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst
@@ -128,6 +128,10 @@ OPTIONS
 	-f, --bpffs
 		  Show file names of pinned maps.
 
+	-n, --nomount
+		  Do not automatically attempt to mount any virtual file system
+		  (such as tracefs or BPF virtual file system) when necessary.
+
 EXAMPLES
 ========
 **# bpftool map show**
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index 53920ffc48dd..58c8369b77dd 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -161,6 +161,10 @@ OPTIONS
 	-m, --mapcompat
 		  Allow loading maps with unknown map definitions.
 
+	-n, --nomount
+		  Do not automatically attempt to mount any virtual file system
+		  (such as tracefs or BPF virtual file system) when necessary.
+
 EXAMPLES
 ========
 **# bpftool prog show**
diff --git a/tools/bpf/bpftool/Documentation/bpftool.rst b/tools/bpf/bpftool/Documentation/bpftool.rst
index 129b7a9c0f9b..e1677e81ed59 100644
--- a/tools/bpf/bpftool/Documentation/bpftool.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool.rst
@@ -60,6 +60,10 @@ OPTIONS
 	-m, --mapcompat
 		  Allow loading maps with unknown map definitions.
 
+	-n, --nomount
+		  Do not automatically attempt to mount any virtual file system
+		  (such as tracefs or BPF virtual file system) when necessary.
+
 
 SEE ALSO
 ========
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 1bad6602a282..897483457bf0 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -177,6 +177,12 @@ int mount_bpffs_for_pin(const char *name)
 		/* nothing to do if already mounted */
 		goto out_free;
 
+	if (block_mount) {
+		p_err("no BPF file system found, not mounting it due to --nomount option");
+		err = -1;
+		goto out_free;
+	}
+
 	err = mnt_fs(dir, "bpf", err_str, ERR_MAX_LEN);
 	if (err) {
 		err_str[ERR_MAX_LEN - 1] = '\0';
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 9e657e7d5172..f44a1c2c4ea0 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -24,6 +24,7 @@ json_writer_t *json_wtr;
 bool pretty_output;
 bool json_output;
 bool show_pinned;
+bool block_mount;
 int bpf_flags;
 struct pinned_obj_table prog_table;
 struct pinned_obj_table map_table;
@@ -313,6 +314,7 @@ int main(int argc, char **argv)
 		{ "version",	no_argument,	NULL,	'V' },
 		{ "bpffs",	no_argument,	NULL,	'f' },
 		{ "mapcompat",	no_argument,	NULL,	'm' },
+		{ "nomount",	no_argument,	NULL,	'n' },
 		{ 0 }
 	};
 	int opt, ret;
@@ -321,13 +323,14 @@ int main(int argc, char **argv)
 	pretty_output = false;
 	json_output = false;
 	show_pinned = false;
+	block_mount = false;
 	bin_name = argv[0];
 
 	hash_init(prog_table.table);
 	hash_init(map_table.table);
 
 	opterr = 0;
-	while ((opt = getopt_long(argc, argv, "Vhpjfm",
+	while ((opt = getopt_long(argc, argv, "Vhpjfmn",
 				  options, NULL)) >= 0) {
 		switch (opt) {
 		case 'V':
@@ -354,6 +357,9 @@ int main(int argc, char **argv)
 		case 'm':
 			bpf_flags = MAPS_RELAX_COMPAT;
 			break;
+		case 'n':
+			block_mount = true;
+			break;
 		default:
 			p_err("unrecognized option '%s'", argv[optind - 1]);
 			if (json_output)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 9e4499c926fa..052c91d4dc55 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -44,7 +44,8 @@
 #define HELP_SPEC_PROGRAM						\
 	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG }"
 #define HELP_SPEC_OPTIONS						\
-	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} | {-m|--mapcompat}"
+	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} |\n"	\
+	"\t            {-m|--mapcompat} | {-n|--nomount} }"
 #define HELP_SPEC_MAP							\
 	"MAP := { id MAP_ID | pinned FILE }"
 
@@ -85,6 +86,7 @@ extern const char *bin_name;
 extern json_writer_t *json_wtr;
 extern bool json_output;
 extern bool show_pinned;
+extern bool block_mount;
 extern int bpf_flags;
 extern struct pinned_obj_table prog_table;
 extern struct pinned_obj_table map_table;
diff --git a/tools/bpf/bpftool/tracelog.c b/tools/bpf/bpftool/tracelog.c
index 2dc36dfa0896..e80a5c79b38f 100644
--- a/tools/bpf/bpftool/tracelog.c
+++ b/tools/bpf/bpftool/tracelog.c
@@ -91,6 +91,9 @@ static bool get_tracefs_pipe(char *mnt)
 	if (found && validate_tracefs_mnt(mnt, TRACEFS_MAGIC))
 		goto exit_found;
 
+	if (block_mount)
+		return false;
+
 	p_info("could not find tracefs, attempting to mount it now");
 	/* Most of the time, tracefs is automatically mounted by debugfs at
 	 * /sys/kernel/debug/tracing when we try to access it. If we could not