]> err.no Git - linux-2.6/commit
markers: fix markers read barrier for multiple probes
authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Wed, 30 Jul 2008 05:33:31 +0000 (22:33 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 30 Jul 2008 16:41:45 +0000 (09:41 -0700)
commit5def9a3a22e09c99717f41ab7f07ec9e1a1f3ec8
treebff29b34c38efdb4da902e6c6a23be0df8e9b854
parentb68bb2632453a9ca7d10a00d79adf60968cb4c05
markers: fix markers read barrier for multiple probes

Paul pointed out two incorrect read barriers in the marker handler code in
the path where multiple probes are connected.  Those are ordering reads of
"ptype" (single or multi probe marker), "multi" array pointer, and "multi"
array data access.

It should be ordered like this :

read ptype
smp_rmb()
read multi array pointer
smp_read_barrier_depends()
access data referenced by multi array pointer

The code with a single probe connected (optimized case, does not have to
allocate an array) has correct memory ordering.

It applies to kernel 2.6.26.x, 2.6.25.x and linux-next.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/marker.c