From: Paul Gortmaker <paul.gortmaker@windriver.com>
To: linux-kernel@vger.kernel.org
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>,
Andi Kleen <ak@linux.intel.com>, Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
John Ogness <john.ogness@linutronix.de>
Subject: [PATCH 1/3] clear_warn_once: expand debugfs to include read support
Date: Thu, 26 Nov 2020 01:30:27 -0500 [thread overview]
Message-ID: <20201126063029.2030-2-paul.gortmaker@windriver.com> (raw)
In-Reply-To: <20201126063029.2030-1-paul.gortmaker@windriver.com>
The existing clear_warn_once variable is write-only; used as per the
documentation to reset the warn_once to as-booted state with:
echo 1 > /sys/kernel/debug/clear_warn_once
The objective is to expand on that functionality, which requires the
debugfs variable to be read/write and not just write-only.
Here, we deal with the debugfs boilerplate associated with converting
it from write-only to read-write, in order to factor that out for easier
review, and for what may be a possible future useful bisect point.
Existing functionality is unchanged - the only difference is that we
have tied in a variable that lets you now read the variable and see
the last value written.
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/panic.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/kernel/panic.c b/kernel/panic.c
index 332736a72a58..1d425970a50c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -654,21 +654,36 @@ EXPORT_SYMBOL(__warn_printk);
/* Support resetting WARN*_ONCE state */
-static int clear_warn_once_set(void *data, u64 val)
+static u64 warn_once_reset;
+
+static void do_clear_warn_once(void)
{
generic_bug_clear_once();
memset(__start_once, 0, __end_once - __start_once);
+}
+
+static int warn_once_get(void *data, u64 *val)
+{
+ *val = warn_once_reset;
+ return 0;
+}
+
+static int warn_once_set(void *data, u64 val)
+{
+ warn_once_reset = val;
+
+ do_clear_warn_once();
return 0;
}
-DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, NULL, clear_warn_once_set,
- "%lld\n");
+DEFINE_DEBUGFS_ATTRIBUTE(clear_warn_once_fops, warn_once_get, warn_once_set,
+ "%llu\n");
static __init int register_warn_debugfs(void)
{
/* Don't care about failure */
- debugfs_create_file_unsafe("clear_warn_once", 0200, NULL, NULL,
- &clear_warn_once_fops);
+ debugfs_create_file_unsafe("clear_warn_once", 0600, NULL,
+ &warn_once_reset, &clear_warn_once_fops);
return 0;
}
--
2.25.1
next prev parent reply other threads:[~2020-11-26 6:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-26 6:30 [PATCH 0/3] clear_warn_once: add timed interval resetting Paul Gortmaker
2020-11-26 6:30 ` Paul Gortmaker [this message]
2020-11-26 6:30 ` [PATCH 2/3] clear_warn_once: bind a timer to written reset value Paul Gortmaker
2020-11-30 16:20 ` Steven Rostedt
2020-11-30 17:17 ` Paul Gortmaker
2020-12-01 3:36 ` Steven Rostedt
2020-11-26 6:30 ` [PATCH 3/3] clear_warn_once: add a warn_once_reset= boot parameter Paul Gortmaker
2020-11-27 16:13 ` [PATCH 0/3] clear_warn_once: add timed interval resetting Petr Mladek
2020-11-27 17:43 ` Paul Gortmaker
2020-12-01 12:59 ` Petr Mladek
2020-11-30 6:02 ` Sergey Senozhatsky
2020-11-30 16:24 ` Steven Rostedt
2020-11-30 3:08 ` Andi Kleen
2020-11-30 17:38 ` Paul Gortmaker
2020-12-01 12:49 ` Petr Mladek
2020-12-01 18:05 ` Paul Gortmaker
2020-12-09 16:37 ` Petr Mladek
2020-12-09 17:21 ` Paul Gortmaker
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