[PATCH] relayfs: remove warning printk() in relay_switch_subbuf()
There's currently a diagnostic printk in relay_switch_subbuf() meant as
a warning if you accidentally try to log an event larger than the
sub-buffer size.
The problem is if this happens while logging from somewhere it's not
safe to be doing printks, such as in the scheduler, you can end up with
a deadlock. This patch removes the warning from relay_switch_subbuf()
and instead prints some diagnostic info when the channel is closed.
Thanks to Mathieu Desnoyers for pointing out the problem and
suggesting a fix.
Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
index cfafc3e..fb7e807 100644
--- a/include/linux/relayfs_fs.h
+++ b/include/linux/relayfs_fs.h
@@ -20,9 +20,9 @@
#include <linux/kref.h>
/*
- * Tracks changes to rchan_buf struct
+ * Tracks changes to rchan/rchan_buf structs
*/
-#define RELAYFS_CHANNEL_VERSION 5
+#define RELAYFS_CHANNEL_VERSION 6
/*
* Per-cpu relay channel buffer
@@ -60,6 +60,7 @@
struct rchan_callbacks *cb; /* client callbacks */
struct kref kref; /* channel refcount */
void *private_data; /* for user-defined data */
+ size_t last_toobig; /* tried to log event > subbuf size */
struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
};