linux/arch/sparc
Paul E. McKenney 3d3eeb2ef2 sparc64: Eliminate obsolete __handle_softirq() function
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 <mroos@linux.ee>
Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Meelis Roos <mroos@linux.ee>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-04-13 11:58:38 -07:00
..
boot Kbuild: centralize MKIMAGE and cmd_uimage definitions 2012-03-26 15:49:20 +02:00
configs
include/asm Merge branch 'for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping 2012-04-04 17:13:43 -07:00
kernel sparc64: Eliminate obsolete __handle_softirq() function 2012-04-13 11:58:38 -07:00
lib
math-emu Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
mm sparc/mm/fault_32.c: Port OOM changes to do_sparc_fault 2012-04-04 15:42:24 -07:00
oprofile
prom Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2012-03-29 14:49:45 -07:00
Kconfig.debug
Makefile sparc32: Add -Av8 to assembler command line. 2012-03-13 18:19:51 -07:00