linux-kernel - [PATCH v3] kdb: Remove the misfeature 'KDBFLAGS'

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Date:   Thu, 21 May 2020 15:21:25 +0800
From:   Wei Li <liwei391@...wei.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Doug Anderson <dianders@...omium.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        "Masahiro Yamada" <yamada.masahiro@...ionext.com>
CC:     <kgdb-bugreport@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] kdb: Remove the misfeature 'KDBFLAGS'

Currently, 'KDBFLAGS' is an internal variable of kdb, it is combined
by 'KDBDEBUG' and state flags. It will be shown only when 'KDBDEBUG'
is set, and the user can define an environment variable named 'KDBFLAGS'
too. These are puzzling indeed.

After communication with Daniel, it seems that 'KDBFLAGS' is a misfeature.
So let's replace 'KDBFLAGS' with 'KDBDEBUG' to just show the value we
wrote into. After this modification, we can use `md4c1 kdb_flags` instead,
to observe the state flags.

Suggested-by: Daniel Thompson <daniel.thompson@...aro.org>
Signed-off-by: Wei Li <liwei391@...wei.com>
---
v2 -> v3:
 - Change to replace the internal env 'KDBFLAGS' with 'KDBDEBUG'.
v1 -> v2:
 - Fix lack of braces.

 kernel/debug/kdb/kdb_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 4fc43fb17127..392029287083 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -418,8 +418,7 @@ int kdb_set(int argc, const char **argv)
 				    argv[2]);
 			return 0;
 		}
-		kdb_flags = (kdb_flags &
-			     ~(KDB_DEBUG_FLAG_MASK << KDB_DEBUG_FLAG_SHIFT))
+		kdb_flags = (kdb_flags & ~KDB_DEBUG(MASK))
 			| (debugflags << KDB_DEBUG_FLAG_SHIFT);
 
 		return 0;
@@ -2081,7 +2080,8 @@ static int kdb_env(int argc, const char **argv)
 	}
 
 	if (KDB_DEBUG(MASK))
-		kdb_printf("KDBFLAGS=0x%x\n", kdb_flags);
+		kdb_printf("KDBDEBUG=0x%x\n",
+			(kdb_flags & KDB_DEBUG(MASK)) >> KDB_DEBUG_FLAG_SHIFT);
 
 	return 0;
 }
-- 
2.17.1