[PATCH 4.4 051/137] cifs: Ratelimit kernel log messages

Greg Kroah-Hartman
2016-02-24T04:14:31Z

From: Jamie Bainbridge <jamie.bainbridge@gmail.com>

commit ec7147a99e33a9e4abad6fc6e1b40d15df045d53 upstream.

Under some conditions, CIFS can repeatedly call the cifs_dbg() logging
wrapper. If done rapidly enough, the console framebuffer can softlockup
or "rcu_sched self-detected stall". Apply the built-in log ratelimiters
to prevent such hangs.

Signed-off-by: Jamie Bainbridge <jamie.bainbridge@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/cifs_debug.c | 2 +-
fs/cifs/cifs_debug.h | 9 ++++-----
2 files changed, 5 insertions(+), 6 deletions(-)

--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -50,7 +50,7 @@ void cifs_vfs_err(const char *fmt, ...)
vaf.fmt = fmt;
vaf.va = &args;

- pr_err("CIFS VFS: %pV", &vaf);
+ pr_err_ratelimited("CIFS VFS: %pV", &vaf);

va_end(args);
}
--- a/fs/cifs/cifs_debug.h
+++ b/fs/cifs/cifs_debug.h
@@ -51,14 +51,13 @@ __printf(1, 2) void cifs_vfs_err(const c
/* information message: e.g., configuration, major event */
#define cifs_dbg(type, fmt, ...) \
do { \
- if (type == FYI) { \
- if (cifsFYI & CIFS_INFO) { \
- pr_debug("%s: " fmt, __FILE__, ##__VA_ARGS__); \
- } \
+ if (type == FYI && cifsFYI & CIFS_INFO) { \
+ pr_debug_ratelimited("%s: " \
+ fmt, __FILE__, ##__VA_ARGS__); \
} else if (type == VFS) { \
cifs_vfs_err(fmt, ##__VA_ARGS__); \
} else if (type == NOISY && type != 0) { \
- pr_debug(fmt, ##__VA_ARGS__); \
+ pr_debug_ratelimited(fmt, ##__VA_ARGS__); \
} \
} while (0)