Theodore Tso wrote: > On Fri, Jun 19, 2009 at 04:14:23PM +0800, Li Zefan wrote: >>> rcu_read_lock(); >>> if (devcache[i] && devcache[i]->device == device) { >>> ret = devcache[i]->devname; >>> rcu_read_unlock(); >>> return ret; >> It doesn't seem safe to dereference @ret outside rcu read section. > > Note the comments at the beginning of the function: > Ah, I overlooked the comments. But the patch that adds rcu locking around trace event prints never gets merged: http://lkml.org/lkml/2009/4/15/549 Steven? > The caller should use rcu_read_lock() in order to make sure the > device name stays valid until its done with it. We use > rcu_read_lock() as well to make sure we're safe in case the caller > gets sloppy, and because rcu_read_lock() is cheap and can be safely > nested. > > I suppose I should change the wording to indicate that it adds a bit > more safety (as in, the crash won't happen inside this function, but > as far as the caller is concerned, all bets are off!) > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html