tree 634eff43e1926bdb400d038eb08115193b6a7506
parent df019b1d8b893d0f0ee5a9b0f71486f0892561ae
author Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com> 1137010662 -0800
committer Linus Torvalds <torvalds@g5.osdl.org> 1137033732 -0800

[PATCH] kprobes: fix race in recovery of reentrant probe

There is a window where a probe gets removed right after the probe is hit
on some different cpu.  In this case probe handlers can't find a matching
probe instance related to break address.  In this case we need to read the
original instruction at break address to see if that is not a break/int3
instruction and recover safely.

Previous code had a bug where we were not checking for the above race in
case of reentrant probes and the below patch fixes this race.

Tested on IA64, Powerpc, x86_64.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>