diff options
Diffstat (limited to 'features/clear_warn_once/clear_warn_once-expand-debugfs-to-include-read-suppo.patch')
| -rw-r--r-- | features/clear_warn_once/clear_warn_once-expand-debugfs-to-include-read-suppo.patch | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/features/clear_warn_once/clear_warn_once-expand-debugfs-to-include-read-suppo.patch b/features/clear_warn_once/clear_warn_once-expand-debugfs-to-include-read-suppo.patch new file mode 100644 index 00000000..c1a46aa5 --- /dev/null +++ b/features/clear_warn_once/clear_warn_once-expand-debugfs-to-include-read-suppo.patch @@ -0,0 +1,77 @@ +From 2365198f516a84982bca08e7b3f862d264b7a17e Mon Sep 17 00:00:00 2001 +From: Paul Gortmaker <paul.gortmaker@windriver.com> +Date: Wed, 16 Dec 2020 12:22:56 -0500 +Subject: [PATCH 1/3] clear_warn_once: expand debugfs to include read support + +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. + +Link: https://lore.kernel.org/r/20201126063029.2030-1-paul.gortmaker@windriver.com +Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> +Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com> +--- + kernel/panic.c | 25 ++++++++++++++++++++----- + 1 file changed, 20 insertions(+), 5 deletions(-) + +diff --git a/kernel/panic.c b/kernel/panic.c +index f470a038b05b..53088219d7df 100644 +--- a/kernel/panic.c ++++ b/kernel/panic.c +@@ -635,21 +635,36 @@ EXPORT_SYMBOL(__warn_printk); + + /* Support resetting WARN*_ONCE state */ + +-static int clear_warn_once_set(void *data, u64 val) ++static u64 clear_warn_once; ++ ++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 = clear_warn_once; ++ return 0; ++} ++ ++static int warn_once_set(void *data, u64 val) ++{ ++ clear_warn_once = 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, ++ &clear_warn_once, &clear_warn_once_fops); + return 0; + } + +-- +2.19.1 + |