[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/fs/relayfs/relay.c b/fs/relayfs/relay.c
index 16446a1..2a6f7f1 100644
--- a/fs/relayfs/relay.c
+++ b/fs/relayfs/relay.c
@@ -333,8 +333,7 @@
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 @@
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);
}