Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Dongdong Deng <> | Subject | [PATCH 1/2] debug_core: add a memory barrier before atomic_inc(&slaves_in_kgdb) | Date | Fri, 26 Nov 2010 16:28:26 +0800 |
| |
The atomic_inc operation of slaves_in_kgdb could be executed on multi-cpus at the same time when kgdb have more than one slave cpu.
Due to the atomic_inc() function do not imply memory barrier, a missing memory barrier here maybe could casue an incorrect value of slaves_in_kgdb, then let kgdb confused.
Add a memory barrier before atomic_inc(&slaves_in_kgdb) to avoid that potential problem.
Signed-off-by: Dongdong Deng <libfetion@gmail.com> --- kernel/debug/debug_core.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index cefd4a1..bec8af0 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -468,10 +468,13 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, kgdb_info[ks->cpu].enter_kgdb++; kgdb_info[ks->cpu].exception_state |= exception_state; - if (exception_state == DCPU_WANT_MASTER) + if (exception_state == DCPU_WANT_MASTER) { + smp_mb__before_atomic_inc(); atomic_inc(&masters_in_kgdb); - else + } else { + smp_mb__before_atomic_inc(); atomic_inc(&slaves_in_kgdb); + } if (arch_kgdb_ops.disable_hw_break) arch_kgdb_ops.disable_hw_break(regs); -- 1.6.0.4
| ![\](/images/icornerr.gif) |