netconsole: fix appending sysdata when sysdata_fields == SYSDATA_RELEASE

Before appending sysdata, prepare_extradata() checks if any feature is
enabled in sysdata_fields (and exits early if none is enabled).

When SYSDATA_RELEASE was introduced, we missed adding it to the list of
features being checked against sysdata_fields in prepare_extradata().
The result was that, if only SYSDATA_RELEASE is enabled in
sysdata_fields, we incorreclty exit early and fail to append the
release.

Instead of checking specific bits in sysdata_fields, check if
sysdata_fields has ALL bit zeroed and exit early if true. This fixes
case when only SYSDATA_RELEASE enabled and makes the code more general /
less error prone in future feature implementation.

Signed-off-by: Gustavo Luiz Duarte <[email protected]>
Reviewed-by: Breno Leitao <[email protected]>
Fixes: cfcc923 ("netconsole: append release to sysdata")
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: gustavold

drivers/net/netconsole.c

@@ -1252,15 +1252,14 @@ static int sysdata_append_release(struct netconsole_target *nt, int offset)
  */
 static int prepare_extradata(struct netconsole_target *nt)
 {
-	u32 fields = SYSDATA_CPU_NR | SYSDATA_TASKNAME;
 	int extradata_len;
 
 	/* userdata was appended when configfs write helper was called
 	 * by update_userdata().
 	 */
 	extradata_len = nt->userdata_length;
 
-	if (!(nt->sysdata_fields & fields))
+	if (!nt->sysdata_fields)
 		goto out;
 
 	if (nt->sysdata_fields & SYSDATA_CPU_NR)