linux

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Haavard Skinnemoen 325d6f5593 avr32: Fix OCD refcounting bug

Iff the parent has TIF_DEBUG set, _and_ clone_flags includes
CLONE_PTRACE we should set the TIF_DEBUG flag for the child and
increment the ocd refcount. Otherwise, the TIF_DEBUG flag must be
unset.

Currently, the child inherits TIF_DEBUG from the parent before
copy_thread is called, so TIF_DEBUG may be already be set before we
determine whether the child is supposed to inherit debugging
capabilities from the parent or not. This means that ocd_enable()
won't increment the refcount, because TIF_DEBUG is already set, and
that TIF_DEBUG will be set for processes that aren't being debugged.

This leads to a refcounting asymmetry, which may show up as

------------[ cut here ]------------
Badness at arch/avr32/kernel/ocd.c:73
PC is at ocd_disable+0x34/0x60
LR is at put_lock_stats+0xa/0x20

as reported by David Brownell. Happens when strace'ing a process that
forks a new child process, e.g. "strace mount -tjffs2 mtd1 /mnt", and
subsequently killing the child process (e.g. "umount /mnt".)

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

2008-02-27 14:23:53 +01:00

asm-offsets.c

[AVR32] Follow the rules when dealing with the OCD system

2007-12-07 14:54:46 +01:00

avr32_ksyms.c

[AVR32] Export clear_page symbol

2007-01-26 13:12:25 +01:00

cpu.c

[AVR32] constify function pointer tables

2008-01-25 08:31:43 +01:00

entry-avr32b.S

[AVR32] Fix wrong pt_regs in critical exception handler