From b4dc885ce0f1783365190d2264ec076b1ca8a777 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 13 Apr 2012 03:35:13 +0000 Subject: [PATCH] sparc64: Eliminate obsolete __handle_softirq() function commit 3d3eeb2ef26112a200785e5fca58ec58dd33bf1e upstream. The invocation of softirq is now handled by irq_exit(), so there is no need for sparc64 to invoke it on the trap-return path. In fact, doing so is a bug because if the trap occurred in the idle loop, this invocation can result in lockdep-RCU failures. The problem is that RCU ignores idle CPUs, and the sparc64 trap-return path to the softirq handlers fails to tell RCU that the CPU must be considered non-idle while those handlers are executing. This means that RCU is ignoring any RCU read-side critical sections in those handlers, which in turn means that RCU-protected data can be yanked out from under those read-side critical sections. The shiny new lockdep-RCU ability to detect RCU read-side critical sections that RCU is ignoring located this problem. The fix is straightforward: Make sparc64 stop manually invoking the softirq handlers. Reported-by: Meelis Roos Suggested-by: David Miller Signed-off-by: Paul E. McKenney Tested-by: Meelis Roos Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- Reading git-format-patch failed