[Xen-devel] [PATCH 2/2] xen/mce: fix static variable 'severity_cpu'

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

1. Distinguish 'severity_cpu' used in mcheck_cmn_handler() and
   mce_softirq(), which should be different variables. Otherwise, they
   may interfere with each other if MC# comes during mce_softirq().
2. Always (re-)initialize 'severity_cpu' to clear historical information.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
 xen/arch/x86/cpu/mcheck/mce.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 7618120..d9ab80a 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -177,7 +177,7 @@ void mce_need_clearbank_register(mce_need_clearbank_t 
cbfunc)
 
 static struct mce_softirq_barrier mce_inside_bar, mce_severity_bar;
 static struct mce_softirq_barrier mce_trap_bar;
-static struct mce_softirq_barrier mce_handler_init_bar;
+static struct mce_softirq_barrier mce_handler_init_bar, mce_softirq_init_bar;
 
 /*
  * mce_logout_lock should only be used in the trap handler,
@@ -187,8 +187,6 @@ static struct mce_softirq_barrier mce_handler_init_bar;
  */
 static DEFINE_SPINLOCK(mce_logout_lock);
 
-static atomic_t severity_cpu = ATOMIC_INIT(-1);
-
 const struct mca_error_handler *__read_mostly mce_dhandlers;
 const struct mca_error_handler *__read_mostly mce_uhandlers;
 unsigned int __read_mostly mce_dhandler_num;
@@ -452,7 +450,7 @@ static int mce_urgent_action(const struct cpu_user_regs 
*regs,
 /* Shared #MC handler. */
 void mcheck_cmn_handler(const struct cpu_user_regs *regs)
 {
-    static atomic_t found_error;
+    static atomic_t severity_cpu, found_error;
     static cpumask_t mce_fatal_cpus;
     struct mca_banks *bankmask = mca_allbanks;
     struct mca_banks *clear_bank = __get_cpu_var(mce_clear_banks);
@@ -461,6 +459,7 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
     struct mca_summary bs;
 
     mce_barrier_enter(&mce_handler_init_bar);
+    atomic_set(&severity_cpu, -1);
     atomic_set(&found_error, 0);
     cpumask_clear(&mce_fatal_cpus);
     mce_barrier_exit(&mce_handler_init_bar);
@@ -1704,11 +1703,16 @@ static int mce_delayed_action(mctelem_cookie_t mctc)
 /* Softirq Handler for this MCE# processing */
 static void mce_softirq(void)
 {
+    static atomic_t severity_cpu;
     int cpu = smp_processor_id();
     unsigned int workcpu;
 
     mce_printk(MCE_VERBOSE, "CPU%d enter softirq\n", cpu);
 
+    mce_barrier_enter(&mce_softirq_init_bar);
+    atomic_set(&severity_cpu, -1);
+    mce_barrier_exit(&mce_softirq_init_bar);
+
     mce_barrier_enter(&mce_inside_bar);
 
     /*
@@ -1774,6 +1778,7 @@ void mce_handler_init(void)
     mce_barrier_init(&mce_severity_bar);
     mce_barrier_init(&mce_trap_bar);
     mce_barrier_init(&mce_handler_init_bar);
+    mce_barrier_init(&mce_softirq_init_bar);
     spin_lock_init(&mce_logout_lock);
     open_softirq(MACHINE_CHECK_SOFTIRQ, mce_softirq);
 }
-- 
2.10.1


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