get-features: Don't try to read the data buffer for sel == 3

When sel == 3, the controller returns capabilities in the completion
entry and does not produce a feature value blob.  Stop allocating
space for the blob and displaying it -- the result is garbage.

Signed-off-by: Andy Lutomirski <luto@kernel.org>

diff --git a/nvme.c b/nvme.c
index 24fdce9593bc800982cb78d0729278cb7a2585b9..00a64669e996e4eebc52f3e1669a1e50235abf7d 100644 (file)
--- a/nvme.c
+++ b/nvme.c
@@ -1119,6 +1119,9 @@ static int get_feature(int argc, char **argv, struct command *cmd, struct plugin
                cfg.data_len = 8;
                break;
        }
+
+       if (cfg.sel == 3)
+               cfg.data_len = 0;
        
        if (cfg.data_len) {
                if (posix_memalign(&buf, getpagesize(), cfg.data_len)) {
@@ -1135,7 +1138,7 @@ static int get_feature(int argc, char **argv, struct command *cmd, struct plugin
                        printf("get-feature:%#02x (%s), %s value:%#08x\n", cfg.feature_id,
                                nvme_feature_to_string(cfg.feature_id),
                                nvme_select_to_string(cfg.sel), result);
-                       if (cfg.human_readable)
+                       if (cfg.human_readable && buf)
                                nvme_feature_show_fields(cfg.feature_id, result, buf);
                        else if (buf)
                                d(buf, cfg.data_len, 16, 1);