From: Li Zhong Date: Sun, 18 Dec 2011 16:03:04 +0000 (+0000) Subject: powerpc: Fix unpaired probe_hcall_entry and probe_hcall_exit X-Git-Tag: v3.2.1~37 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ddcf85d72ffe4fd46239a94253fe04c114d4d1e2;p=pandora-kernel.git powerpc: Fix unpaired probe_hcall_entry and probe_hcall_exit commit e4f387d8db3ba3c2dae4d8bdfe7bb5f4fe1bcb0d upstream. Unpaired calling of probe_hcall_entry and probe_hcall_exit might happen as following, which could cause incorrect preempt count. __trace_hcall_entry => trace_hcall_entry -> probe_hcall_entry => get_cpu_var => preempt_disable __trace_hcall_exit => trace_hcall_exit -> probe_hcall_exit => put_cpu_var => preempt_enable where: A => B and A -> B means A calls B, but => means A will call B through function name, and B will definitely be called. -> means A will call B through function pointer, so B might not be called if the function pointer is not set. So error happens when only one of probe_hcall_entry and probe_hcall_exit get called during a hcall. This patch tries to move the preempt count operations from probe_hcall_entry and probe_hcall_exit to its callers. Reported-by: Paul E. McKenney Signed-off-by: Li Zhong Tested-by: Paul E. McKenney Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed