From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Date: Fri, 18 Jan 2008 16:20:46 +0000 Subject: [PATCH]Fix the order of atomic operations in restore_previous_kprobes Message-Id: <4790D1DE.8030700@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: tony.luck@intel.com, Shaohua Li Cc: ia64 , LKML , systemtap-ml From: Masami Hiramatsu Fix the order of atomic operations to prevent overwriting prev_kprobe[0]. To pop values from stack, we must decrement stack index right AFTER reading values. Signed-off-by: Masami Hiramatsu --- Details of this issue was reported to http://sources.redhat.com/bugzilla/show_bug.cgi?id 71 arch/ia64/kernel/kprobes.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) Index: 2.6.24-rc8/arch/ia64/kernel/kprobes.c =================================--- 2.6.24-rc8.orig/arch/ia64/kernel/kprobes.c 2008-01-17 21:14:01.000000000 -0500 +++ 2.6.24-rc8/arch/ia64/kernel/kprobes.c 2008-01-17 21:14:01.000000000 -0500 @@ -381,9 +381,10 @@ static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) { unsigned int i; - i = atomic_sub_return(1, &kcb->prev_kprobe_index); - __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i].kp; - kcb->kprobe_status = kcb->prev_kprobe[i].status; + i = atomic_read(&kcb->prev_kprobe_index); + __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i-1].kp; + kcb->kprobe_status = kcb->prev_kprobe[i-1].status; + atomic_sub(1, &kcb->prev_kprobe_index); } static void __kprobes set_current_kprobe(struct kprobe *p, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division e-mail: mhiramat@redhat.com, masami.hiramatsu.pt@hitachi.com