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authorTom Zanussi <zanussi@us.ibm.com>2005-12-20 22:10:22 +0300
committerLinus Torvalds <torvalds@g5.osdl.org>2005-12-21 04:33:22 +0300
commitfd30fc3256824f03c2ff9317269d66f72f7042ca (patch)
tree863a1ba4ddae961e2727343c17d15f64c3f4d463
parentbb44f116a14c4c932f15c79acfafd46bcb43ca9a (diff)
downloadlinux-fd30fc3256824f03c2ff9317269d66f72f7042ca.tar.xz
[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>
-rw-r--r--fs/relayfs/relay.c8
-rw-r--r--include/linux/relayfs_fs.h5
2 files changed, 9 insertions, 4 deletions
diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
index 16446a15c96d..2a6f7f12b7f9 100644
--- a/fs/relayfs/relay.c
+++ b/fs/relayfs/relay.c
@@ -333,8 +333,7 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
return length;
toobig:
- printk(KERN_WARNING "relayfs: event too large (%Zd)\n", length);
- WARN_ON(1);
+ buf->chan->last_toobig = length;
return 0;
}
@@ -399,6 +398,11 @@ void relay_close(struct rchan *chan)
relay_close_buf(chan->buf[i]);
}
+ if (chan->last_toobig)
+ printk(KERN_WARNING "relayfs: one or more items not logged "
+ "[item size (%Zd) > sub-buffer size (%Zd)]\n",
+ chan->last_toobig, chan->subbuf_size);
+
kref_put(&chan->kref, relay_destroy_channel);
}
diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
index cfafc3e76bc2..fb7e80737325 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
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 */
};