Messages in this thread Patch in this message |  | | From | Paul Gortmaker <> | Subject | [PATCH 1/3] clear_warn_once: expand debugfs to include read support | Date | Thu, 26 Nov 2020 01:30:27 -0500 |
| |
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
|  |